Patent Publication Number: US-11381549-B2

Title: Downloadable security and protection methods and apparatus

Description:
PRIORITY AND RELATED APPLICATIONS 
     This application is a divisional of and claims priority to co-owned U.S. patent application Ser. No. 15/925,554 of the same title filed Mar. 19, 2018, issuing as U.S. Pat. No. 10,362,018 on Jul. 23, 2019, which is a divisional of and claims priority to co-owned U.S. patent application Ser. No. 15/096,065 of the same title filed Apr. 11, 2016, issued as U.S. Pat. No. 9,923,883 on Mar. 20, 2018, which is a divisional of and claims priority to co-owned U.S. patent application Ser. No. 14/010,365 of the same title filed Aug. 26, 2013, issued as U.S. Pat. No. 9,313,458 on Apr. 12, 2016, which is a divisional of and claims priority to co-owned U.S. patent application Ser. No. 11/584,208 of the same title filed Oct. 20, 2006, issued as U.S. Pat. No. 8,520,850 on Aug. 27, 2013, each of the foregoing which is incorporated herein by reference in its entirety. 
     This application is related to U.S. patent application Ser. No. 11/006,404 filed Dec. 7, 2004, entitled “Technique For Securely Communicating And Storing Programming Material In A Trusted Domain”, issued as U.S. Pat. No. 8,312,267 on Nov. 13, 2012, which is incorporated herein by reference in its entirety. 
    
    
     COPYRIGHT 
     A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates generally to the field of content and/or data delivery over a network. More particularly, the present invention is related to apparatus and methods for distributing programming content, media, data and other information services according to downloadable conditional access (CA), trusted domain (TD) and/or digital rights management (DRM) schemes. 
     2. Description of Related Technology 
     Recent advances in digital information processing have made a wide range of services and functions available for delivery to consumers at their premises for very reasonable prices or subscription fees. These services and functions include digital programming (movies, etc.), digital video-on-demand (VOD), personal video recorder (PVR), Internet Protocol television (IPTV), digital media playback and recording, as well high-speed Internet access and IP-based telephony (e.g., VoIP). Other services available to network users include access to and recording of digital music (e.g., MP3 files), as well local area networking (including wire-line and wireless local area networks) for distributing these services throughout the user&#39;s premises, and beyond. 
     Currently, many of these services are provided and delivered to the user via a wide variety of different equipment environments including, inter alia, cable modems, WiFi hubs, Ethernet hubs, gateways, switches and routers, computers, servers, cable set-top boxes, PSTNs, cellular telephones/smartphones, PDAs, and portable digital music devices such as the Apple iPod™. Additionally, the services associated with such technology are typically provided by multiple vendors including e.g., a cable service provider (e.g., MSO), cellular service provider (CSP), wireless service provider (WSP), VoIP service provider, music download service, Internet service provider (ISP), PSTN telephone service, etc. 
     The myriad of services, equipment and providers can easily create confusion and economic inefficiency for someone using many of these services on a regular basis. In particular, a user may have to pay for each service or equipment separately, thus eliminating any economies of scale based on integration. Additionally, the equipment or services may not interoperate with one another, thus reducing the overall utility provided to the user, and increasing their frustration level. These problems are particularly acute when the number of different services utilized (and hence number of service providers) is high. 
     Some improvements in digital service integration have been made over time. For example, cable system subscribers (such as those of the Assignee hereof) can now access VOD, PVR, PPV and broadcast services simultaneously, as well a Internet access via cable modem, and even digital telephony (e.g., VoIP). However, these functions are still substantially disparate in terms of their hardware and software environments (i.e., the user must have a cable modem, set-top box, VoIP telephony unit, PC, etc.), and “cross-over” between the environments (e.g., moving content or data from one environment to the other) is quite limited. 
     Moreover, the movement of content delivered by these services within the user&#39;s premises (or even outside) is substantially frustrated, largely due to concerns relating to protection of valuable (e.g., copyrighted) content and surreptitious reproduction and distribution. Such unauthorized reproduction and distribution not only detracts from the network operator&#39;s revenue and commercial viability, but also that of the content source (e.g., movie studio, recording studio/artist, etc.). 
     Moreover, the lack of a comprehensive and effective scheme for control of content within the user domain effectively precludes content providers from releasing new content over cable or satellite networks contemporaneous with its availability over retail or rental outlets, due in large part to unauthorized access, reproduction and distribution concerns. Stated simply, new release content availability over cable typically lags that of rental/retail, due primarily to the lack of an effective control mechanism for the content once it is delivered to the user domain. 
     A number of existing technologies have heretofore been employed by network operators in order to attempt to frustrate surreptitious access, copying and distribution of valuable content. These approaches are now described. 
     Conditional Access 
     Conditional access (CA) technologies are typically incorporated into content-based networks, such technologies including the digital encoding of various types of data including audio and video programming and music. Conditional access can generally be defined as the control of when and how a user may view and use the associated programming or information. Different types of conditional access may be desirable in a network delivery system in order to, e.g., accommodate improvements in the technology over time, as well as different conditional access attributes such as security and category of programming or user access level. 
     A variety of traditional methods of conditional access exist including, e.g., “Powerkey”, NDS, and DigiCipher. A generalized conditional access model is also provided by the well-known DVB (Digital Video Broadcasting) Specification TS 101 197 V1.2.1 (02/02), DVB SimulCrypt; Part 1: “Head-end architecture and synchronization”, and TS 103 197 V1.2.1 (02/02): “Head-end Implementation of SimulCrypt”, each incorporated herein by reference in its entirety. These can be implemented using, for example, the so-called “CableCard” plug-in security module access technology (also known as a “a point-of-deployment (POD) module”). See, e.g., the CableCard-Host interface specification, which defines the interface between a digital cable receiver or STB (Host device) and the CableCard device provided by the MSO/cable operator. CableCard was developed to satisfy certain security requirements to allow retail availability of host devices, e.g., set-top boxes, digital cable ready televisions, DVRs, personal computers (PCs), integrated digital televisions, etc., for receiving cable services. The CableCard, comprising a PCMCIA device, can be inserted into a host device, allowing a viewer to receive cable systems&#39; secure digital video services, e.g., pay per view TV, electronic program guides, premium subscription channels, etc. 
     Specifically, the CableCard contains conditional access functionality, as well as the capability of converting messages to a common format. Thus, the CableCard provides a cable operator with a secure device at the subscriber premises, and acts as a translator so that the host device needs to understand a single protocol, regardless of the type of the network to which it is connected. 
     For example, with the CableCards provided by cable operators, host devices which comply with OpenCable specifications, e.g., the an OpenCable Applications Platform (OCAP), may be sold in retail outlets. (For details on such a platform, one may refer, e.g., to: “OpenCable Application Platform Specification,” OCAP 2.0 Profile, OC-SP-OCAP2.0-I01-020419, Cable Television Laboratories, Inc., Apr. 19, 2002, incorporated herein by reference in its entirety.) The OCAP allows applications to be built to a common middleware layer for deployment on host devices interoperable across cable systems in North America. (For details on the functional requirements of one such host device, one may refer, e.g., to: “OpenCable™ Host Device Core Functional Requirements,” OC-SP-HOSR-CFR-I13-030707, Cable Television Laboratories, Inc., Jul. 7, 2003, incorporated herein by reference in its entirety.) With a common interface to the CableCard, a host can be moved from one place to another, provided that the user of the host device contact his/her new cable operator to obtain a new CableCard. (For details on such an interface, one may refer, e.g., to: “OpenCable™ HOST-POD Interface Specification,” OC-SP-HOSTPOD-IF-I13-030707, Cable Television Laboratories, Inc. Jul. 7, 2003, incorporated herein by reference in its entirety.) To provision a new CableCard and host device, an initialization and authorization process needs to be performed while the host device, with the CableCard inserted therein, is connected to the cable network. The initialization and authorization process begins with the user&#39;s providing an ID(s) of the CableCard and/or the host device (e.g., serial number(s)) to the cable operator. The cable operator looks up in a database a MAC address of the CableCard which typically is hard-coded in the CableCard, and is associated with the CableCard ID. During the authorization process, the cable operator may, for example, assign an IP address to the CableCard for its identification in the cable network. The cable operator may also collect from the host device data concerning the make, model, and ID of the host device (e.g., its serial number). The cable operator may associate the CableCard&#39;s MAC address (and/or IP address) with the user information, e.g., his/her name, address, etc. for billing purposes. 
     Encryption 
     In many content-based networks (e.g., cable television systems), the client device or consumer premises equipment (CPE) receives, through the cable TV network, programming content which may be encrypted, e.g., in accordance with the Data Encryption Standard (DES) technique or Advanced Encryption Standard (AES), to secure its delivery. 
     DES is a well-known symmetrical cipher that utilizes a single key for both encryption and decryption of messages. Because the DES algorithm is publicly known, learning the DES key would allow an encrypted message to be read by anyone. As such, both the message sender and receiver must keep the DES key a secret from others. A DES key typically is a sequence of eight bytes, each containing eight bits. To enhance the DES integrity, the DES algorithm may be applied successive times. With this approach, the DES algorithm enciphers and deciphers data, e.g., three times in sequence, using different keys, resulting in a so-called triple DES (3DES) technique. 
     The Advanced Encryption Standard (AES), also known as Rijndael, is a block cipher adopted as an encryption standard by many entities including the U.S. government. It is used worldwide, as is the case with its predecessor, DES. AES was adopted by National Institute of Standards and Technology (NIST) and was codified as US FIPS PUB 197 in November 2001. 
     AES has a fixed block size of 128 bits and a key size of 128, 192 or 256 bits. The key is expanded using the well-known Rijndael key schedule. Most of AES calculations are performed in a special finite field. AES typically operates on a 4×4 array of bytes, termed the state. For encryption, each cycle or round of AES (except the last round) consists of four stages or operations: (i) AddRoundKey, wherein each byte of the state is combined with the round key, and each round key is derived from the cipher key by using the key schedule; (ii) SubBytes, wherein a non-linear substitution is performed such that each byte is replaced with another according to a lookup table; (iii) ShiftRows, wherein a transposition step is performed such that each row of the state is shifted cyclically a given number of steps; and (iv) MixColumns, wherein a mixing operation which operates on the columns of the state is performed, thereby combining the four bytes in each column using a function (e.g., linear transformation). The final round of the algorithm replaces the MixColumns stage with another instance of the AddRoundKey step. 
     AES provides a much higher level of encryption than DES or 3DES, and hence is increasingly being integrated into applications where strong protection is desired, including the delivery of content over cable or other content-based networks. 
     In contrast to the DES or AES techniques, a public key encryption technique, e.g., an RSA technique (named for its developers, Rivest, Shamir, and Adleman), uses two different keys. A first key, referred to as a private key, is kept secret by a user. The other key, referred to as a public key, is available to anyone wishing to communicate with the user in a confidential manner. The two keys uniquely match each other, collectively referred to as a “public \-private key pair.” However, the private key cannot be easily derived from the public key. A party wishing to send a message to the user may utilize the public key to encrypt a message before transmitting it. The user then utilizes the private key to decrypt the message. Conversely, the private key may be used to encrypt a message, in which case the message can subsequently be decrypted with the public key. For example, the keys for the RSA algorithm are mathematically generated, in part, by combining prime numbers. The security of the RSA algorithm, and the like, depends on the use of very large numbers for its keys, which typically are 512 bits long or longer. 
     “Trusted Domains” 
     Another related approach for content protection comprises the creation and enforcement of a “trusted domain” or TD. Specifically, such a “trusted domain” (TD) comprises an area (physically or virtually) within which programming or other content is protected from unauthorized access, distribution and copying. For example, in a cable network, a trusted domain may include not only the network portion where programming content traditionally is secured by, and within total control of, a cable operator (including, e.g., the headend, HFC delivery network, etc.,) but also user devices or customer premises equipment (CPE) at subscribers&#39; premises which are capable of receiving and securely storing programming content. Using the trusted domain approach, the network operator can guarantee certain subscriber access, distribution, and usage policy enforcement with respect to content held within the domain. For example, a digital representation of a movie held within an operator&#39;s TD (e.g., on a hard drive of a user device) cannot be distributed over the Internet, wireless network, etc. in viewable form, and cannot become a source for duplication of multiple viewable copies. 
     One exemplary approach of implementing a trusted domain, described in co-owned and co-pending U.S. patent application Ser. No. 11/006,404 filed Dec. 7, 2004 and entitled “Technique For Securely Communicating And Storing Programming Material In A Trusted Domain”, which is incorporated herein by reference in its entirety, comprises using two cryptographic elements (e.g., encryption keys), associated with a user and his/her client device(s), respectively, that control access to content stored in the client device(s) within the domain. For example, the content stored in the client device may be encrypted using a private or secret key in accordance with the DES or AES algorithms. When the encrypted content is transported from the client device to another device within the domain associated with the same user (or other common parameter or feature), the second device needs the cryptographic element (e.g., the secret key) to decrypt the encrypted content. To that end, the second device also receives from the source device an encrypted version of this secret key. The latter is generated by encrypting the secret key using a second and distinct cryptographic element (e.g., a public key in accordance with a public key algorithm) associated with the subscriber. The second device provides the encrypted version of the secret key to a remote apparatus, e.g., in a headend, where the secret key is recovered based on at least the encrypted version of the secret key and data relating to that user or client device. The second device then receives from the head-end another encrypted version of the secret key, which is generated by encrypting the recovered secret key using a third cryptographic element (e.g., a public key in accordance with a public key algorithm) associated with the second device. Based on at least this second encrypted version of the secret key, the secret key can be recovered in the second device to decrypt the encrypted content. 
     The trusted domain is preserved with respect to the stored content so long as the content remains encrypted and continues to be managed under the above-described key management methodology, regardless of which device stores the content. Once the content itself is decrypted, e.g., by a conditional access (CA) mechanism when data is sent from the SDVR CPE to a television monitor for display, the decrypted content is no longer within the trusted domain. 
     Digital Rights Management (DRM) and Steganograhy 
     Another approach used to control the distribution and use of protected content within a content-based network is to employ so-called digital rights management (DRM). For example, Media rights management systems such as the Microsoft Windows® Media Digital Rights Manager (DRM), may be used as well. The Windows® Media Player Version 9 comprises audio and video codecs, the Windows Media Encoder, Windows Media Server, Windows Media Software Development Kit (SDK), Digital Rights Management (DRM) technology, and an extensibility model that allows integration into third-party solutions. 
     According to one such DRM approach, a digital media or content file is encrypted and locked with a “license key.” The license key is stored in a license file or other data structure which is distributed separately from the media or content. A user can obtain the encrypted media file by, e.g., downloading it from a web site, purchasing it on a physical media, etc. To play the digital media file, the user must first acquire the license file including the license key for that media file. The user acquires the license key by accessing a pre-delivered license (which includes license terms or policies). Alternatively, when the user plays the file for the first time, a procedure is invoked for retrieving the license via a network connection or other delivery mode (e.g., the Internet). After obtaining the license with the license key, the user is able to access the media file according to the rules or rights specified in the license policies. 
     Another approach to DRM (see, e.g., the RealNetworks “Helix” Platform and Community approach) comprises encrypting a content file (typically perfromed by the system operator) to create a secured content file, thereby requiring a cryptographic key to access the content in the file. The key is included within a retailer&#39;s database, and the secured content file is distributed to users by, e.g., Internet connection or offline distribution of CDs. The retailer itself sets usage rules and policies for licensing the content. A user contacts the retailer&#39;s web server, such as via a trusted software client, in order to obtain a license to access the encrypted content. The retailer&#39;s web server requests certain rights from the operator&#39;s license server, the latter which creates a license containing the key for the requested content file. This license is given to the retailer (e.g. via the web server), which delivers the license to the trusted client of the user. The trusted client retrieves the content file, and uses the received key to access the content. 
     Related to DRM is the practice of steganography. Steganography is the art and science of including hidden data in such a way that no one apart from the intended recipient or sender knows of the existence of the data; this is in contrast to cryptography, where the existence of the data itself is not disguised, but the content is obscured. For example, digital steganographic data may included within the recorded data/content, such as digital watermarking data. For example, Digimarc®, SysCoP™, EIKONAmark™, and other similar commercially available watermarking approaches can be used for this purpose. While this approach does not per se prevent or control content access or distribution, it is often an effective post facto method of identification and determining the origin of media (e.g., where it was copied from), and hence knowledge of its presence can act as a significant deterrent to surreptitious reproduction and distribution. 
     Emerging Challenges and Opportunities 
     More recently, emerging technologies have focused on so-called “downloadable” conditional access systems (DCAS), which are intended to be implemented in next-generation two-way, cable-ready digital TV sets, set-top boxes and/or other related devices. This “download” approach would enable cable operators to download conditional access software directly to TV sets, set-top boxes and other digital entertainment devices in the subscribers&#39; premises, and would be especially suited to interactive services such as VOD, PVR, etc. This would also obviate the physical CableCard form factor. 
     With the so-called FCC “navigation order” (Further Notice of Proposed Rulemaking (“FNPRM”), FCC 00-341, adopted Sep. 14, 2000; released Sep. 18, 2000, CS Docket #97-80) relating to, inter alia, the adoption of unidirectional plug and play, cable system operators are also required to support digital cable-ready devices on their systems. Downloadable conditional access (CA) functionality is one proposed conditional access technology that also meets this requirement. In addition to the requirements imposed by FCC 03-225, it is also desirable to support bi-directional cable-ready devices on its systems, as well as “separable security” functionality (i.e., the CA functionality is physically, or at least logically) separable from the host device. Ideally, such enhanced functionality would also allow both basic bi-directional functions (so-called single-stream devices) as well as the use of more advanced multi-stream devices such as digital video recorders (DVRs). It is also desirable to allow download-enabled devices to participate (ad hoc or otherwise) in the operator&#39;s trusted domain (TD). 
     In recent years, numerous systems for providing interconnectivity among devices in a premises (e.g., home, enterprise, university, etc.) have been developed, allowing premises networks to include DSTBs, personal computers, cellphones, PDA devices, etc. Because of the increasing popularity of premises networking and the demand for seamless interconnectivity between heterogeneous hardware/software environments (e.g., “plug and play”), there is a growing need for a strategy that enables a user to perform authorized transfer of protected content, e.g., transferring content from their cable system CPE to other devices in a premises network, or even outside of the network, and at the same time prevent unauthorized distribution and reproduction of the protected content. The foregoing CA, DRM, steganographic, and trusted domain technologies, while providing some degree of protection, simply do not support such control and protection within the increasingly complex user domain. 
     Specifically, these techniques do not support cryptographic key management and distribution systems that operate with both legacy or new CA systems, and are not under direct network operator (e.g., MSO) control. 
     Moreover, such existing techniques often cannot be smoothly integrated with retail (third party) devices, and are typically quite platform specific. They are often also specific to the content delivery mode (i.e., VOD, broadcast, broadcast-switched, and other content delivery paradigms). 
     These techniques also typically will not support seamless transition between independent implementations of CA, trusted domain, and DRM security features and policies, and are not standardized to any significant degree. For example, conditional access (CA) paradigms currently in use are not generally extensible beyond the user&#39;s CPE. So, the user would be prohibited from transferring streamed or downloaded content to their WiFi enabled laptop or PC, since proper conditional access support does not exist in these devices. 
     Prior art conditional access (CA) systems such as the Scientific Atlanta “Powerkey” approach described above have no authentication entity or “proxy” that can authenticate CPE or other connected devices in anticipation of providing download services, no video (media) provisioning system, and hence by nature are highly localized. Generally speaking, any “trusted domains” that might be established are not extendable beyond the CPE  106  on the client side of the delivery network. 
     Thus, improved apparatus and methods for distributing digital services to and within a user premises are needed. Such improved apparatus and services would ideally provide users with a number of diverse digital services in a more integrated and unified fashion, and allow for substantially unrestricted cross-over between different hardware and software environments. 
     These apparatus and methods would also allow for remote, centralized management, configuration, and control of content access, distribution and reproduction within the user domain, as well as extension of the conditional access, trusted domain, and DRM environments outside of merely the user&#39;s set-top box or other such consumer premises equipment (CPE). 
     Moreover, such apparatus and methods would ideally support cryptographic key management and distribution systems that operate with both legacy or new CA systems, under direct network operator (e.g., MSO) control, as well as allowing for integration with retail (third party) devices via, e.g., downloadable components and cryptographic elements sent directly via the operator&#39;s network. 
     Such improved apparatus and methods would also ideally be delivery-mode agnostic; i.e., they would be compatible with VOD, broadcast, broadcast-switched, and other content delivery paradigms, and would further allow for an interoperable architecture with components from different network, secure component, and CPE vendors, in effect standardizing many aspects of content control within the user domain. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the foregoing needs by disclosing apparatus and methods for distributing applications/software, programming, data, media and other information services in a controlled and protected manner within a content-based network, as well as devices or domains associated therewith. 
     In a first aspect of the invention, improved network apparatus is disclosed. In one embodiment, the network apparatus is disposed substantially at a first node of a content-based network and adapted for delivery of security information to a second node of the network. The apparatus comprises: a content provisioning apparatus; a conditional access apparatus in communication with the provisioning apparatus; and an authentication apparatus in communication with at least the conditional access apparatus. At least the authentication and conditional access apparatus are configured to cooperate to transmit to the second node both: (i) at least one cryptographic key, and (ii) encrypted code configured to provide at least protection of the content at the second node. 
     In one variant, the first node comprises a cable system head-end, and the second node comprises a residence or business enterprise. 
     In another variant, the apparatus is configured to deliver the at least one key and encrypted code via a DOCSIS-compliant cable modem. 
     In another variant, the apparatus is configured to deliver the at least one key and encrypted code via an in-band downstream QAM. 
     In another variant, the first node comprises a hub within a broadcast switched architecture (BSA) network. 
     In another variant, the network apparatus further comprises a personalization server (PS) apparatus in communication with the conditional access system, the PS being adapted to select at least one cryptographic key and encrypted code based at least in part on a communication received from a client device disposed at the second node. An interface to a trusted authority (TA) is also provided, the TA providing the at least one cryptographic key to the PS based at least in part on information contained in the communication from the client device to the network apparatus. 
     In yet another variant, the network apparatus further comprises a trusted authority proxy (TAP), the TAP in at least periodic communication with a remote trusted authority (TA), the TAP providing the at least one cryptographic key to the PS based at least in part on information contained in the communication from the client device to the network apparatus, and substantially independent of communication with the TA (or any intermediary device such as for example an authentication proxy). 
     In still another variant, the authentication apparatus comprises software configured to authenticate the client device based at least in part on the communication received from the client device, the authentication comprising a condition precedent for downloading of the at least one key and encrypted code. 
     In still another variant, the encrypted code comprises a secure client adapted to run on a security processor of the client device, and the network apparatus is further configured to transmit a bootloader program to run on the security processor to enable at least a portion of the transmitting of the cryptographic key and encrypted code. The network apparatus may further be configured to transmit second code to the client device, the second code comprising a conditional access (CA) client, the CA client adapted to run on the security processor to enforce at least one CA policy. 
     In a second embodiment, the network apparatus comprises: a content provisioning apparatus; a security management apparatus in communication with the provisioning apparatus; and an authentication apparatus in communication with at least the security management apparatus; wherein at least the authentication and security management apparatus are configured to cooperate to transmit to the second node encrypted code configured to manage at least one of (i) a trusted domain (TD) policies or configuration, and (ii) digital rights management (DRM) policies or configuration, within a client device disposed at the second node. 
     In one variant, the apparatus comprises a personalization server (PS) apparatus in communication with the security management system, the PS being adapted to select the encrypted code based at least in part on a communication received from a client device disposed at the second node, and the authentication apparatus comprises software configured to authenticate the client device based at least in part on the communication received from the client device, the authentication being required before downloading the encrypted code. 
     In another variant, the client device disposed at the second node comprises a premises content distribution apparatus for use with a plurality or media-capable devices, the content distribution apparatus comprising: a first interface capable of at least receiving media content from a first network; a mass storage device in data communication with the first interface and adapted to store at least a portion of the media content; a coaxial cable interface (or other wireline interface such as 802.3 CATS or AC power lines) configured to provide networking throughout at least a portion of the premises over coaxial cable present therein; and a wireless access interface adapted to support at least one wireless network substantially within the premises. The media content is accessible to users on both the coaxial cable network and the at least one wireless network. 
     In another variant, the encrypted code comprises a secure client adapted to run on a security processor of the client device. The network apparatus is further configured to transmit a bootloader program to run on the security processor to enable at least a portion of the transmitting of the encrypted code and a cryptographic key, and to transmit second code to the client device, the second code comprising a TD or DRM client, the TD or DRM client adapted to run on the security processor to enforce at least one TD or DRM policy, respectively. 
     In a second aspect of the invention, a method of operating a security management architecture within a content-based network is disclosed. In one embodiment, the method comprises: providing an encrypted software image to a client device; providing a first cryptographic key to the client device; using the first cryptographic key to enable decryption of the software image; providing at least a second cryptographic key to the client device; and using the second key to decrypt encrypted content delivered to the client device. 
     In one variant, the act of providing at least a second key comprises providing a second key and a third key, the third key being used to decrypt the second key. The second key comprises an encrypted key; the third key comprises an encrypted portion of a public-private key pair; and the method further comprises providing the client device with a private portion of the public-private key pair, the private portion being used to decrypt the third key, the third key being used to decrypt the encrypted second key. 
     In another variant, the act of providing a first key comprises providing an encrypted public portion of a public/private key pair, and the method further comprises: providing the client device with a private portion of the public/private key pair; and decrypting the encrypted public portion using the private portion. 
     In another variant, at least one of the first and second keys is encrypted using a symmetric block cipher algorithm. Similarly, the software image may be encrypted using a symmetric block cipher algorithm comprising a power-of-two key. 
     In a third aspect of the invention, a method of operating a security management architecture within a content-based network is disclosed. In one embodiment, the method comprises: providing an encrypted software image to a client device having a security processor; providing a first cryptographic key to the client device; using the first cryptographic key to enable decryption of the software image; and configuring at least a portion of the security processor of the client device using at least the decrypted software image. 
     In one variant, the act of providing a first key comprises providing an encrypted public portion of a public/private key pair, and the method further comprises: providing the client device with a private portion of the public/private key pair; and decrypting the encrypted public portion using the private portion. 
     In another variant, the act of configuring comprises remotely configuring based at least in part on instructions generated remote from the client device, and the client device comprises an OCAP-compliant digital set-top box, and the acts of providing comprise transmitting the software image and the first key over a hybrid fiber-coax (HFC) network to the client device using a DOCSIS channel for at least one of the image and the first key. The act of providing an encrypted software image to a client device comprises providing at least one of a conditional access (CA), digital rights management (DRM), or trusted domain (TD) client to a secure processor of the set-top box, the at least one client being adapted to enforce at least one security policy within the set-top box. 
     In a fourth aspect of the invention, network security apparatus adapted for transmission of security information to an authenticated client device in data communication with the network is disclosed. In one embodiment, the apparatus comprises: a security management apparatus adapted for communication with the network; and an authentication apparatus in communication with at least the security management apparatus. The authentication and security management apparatus are configured to cooperate to transmit to the authenticated client device: (i) a portion of a public-private key pair, the client device, comprising the other portion of the key pair; and (ii) encrypted code configured to manage at least one aspect of a security architecture within a client device. The public-private key pair is configured to decrypt the encrypted code. 
     In one variant, the apparatus further comprises a trusted authority proxy, the proxy in data communication with the security management apparatus and configured to securely communicate with a remote trusted authority. 
     In another variant, the at least one aspect comprises security policies relating to distributing content delivered to the client device to one or more secure output domains (SODs). 
     In still another variant, the authentication apparatus is configured to communicate with a physically secure processor of the client device in order to authenticate the client device. 
     In a fifth aspect of the invention, a method of remotely providing a trusted domain for content protection within a premises having a client device is disclosed. In one embodiment, the method comprises: transmitting encrypted software to the client over a network; transmitting a first decryption key to the client device; using a second decryption key to access the first decryption key; using the first decryption key to decrypt the software; and using the software to establish at least a portion of the trusted domain within the client device. Using this method, content can be securely transported within the trusted domain. 
     In one variant, the encrypted software comprises a trusted domain (TD) client program, the TD client being adapted to run on a physically secure microprocessor within the client device, the TD client establishing a plurality of security and content distribution policies within the trusted domain, the policies and the trusted domain cooperating to prevent unauthorized reproduction of the content. The encrypted software further comprises a conditional access (CA) client program, the CA client being adapted to run on a physically secure microprocessor within the client device, the CA client establishing a plurality of content access policies within the trusted domain, the access policies and the trusted domain cooperating to prevent unauthorized access to the content. 
     In a sixth aspect of the invention, security apparatus for use with a content-based network is disclosed. In one embodiment, the apparatus comprises: client-side security management apparatus in operative communication with the network and adapted to maintain at least a portion of a trusted domain within a client device; and network security management apparatus in operative communication with the network and the client-side management apparatus, the network security management apparatus adapted to control at least one of the configuration and operation of the client-side apparatus in order to protect content delivered to the client device against unauthorized distribution or reproduction. 
     In one variant, the network security management apparatus comprises: a content provisioning apparatus; a conditional access apparatus in communication with the provisioning apparatus; and an authentication apparatus in communication with at least the conditional access apparatus; wherein the authentication, provisioning and conditional access apparatus are configured to cooperate to transmit to the client device both: (i) at least one cryptographic key, and (ii) encrypted code configured to provide at least protection of the content at the client device. The client-side security management apparatus comprises: a physically secure microprocessor adapted to run the encrypted code after decryption thereof, the encrypted code enforcing at least a portion of a plurality of security policies necessary to maintain the trusted domain; wherein the physically secure microprocessor further comprises: a bootloader function adapted to cause authentication of the secure microprocessor with the authentication apparatus; and a conditional access (CA) client adapted to interface with the conditional access apparatus on the network side in order to establish one or more conditional access policies with respect to the content. 
     In a seventh aspect of the invention, a method of doing business over a content-based network is disclosed. In one embodiment, the method comprises: identifying a plurality of substantially unique client devices in data communication with the network; and selectively configuring at least one of the plurality of client devices based at least in part on a service request from a subscriber associated with the at least one device, the selective configuration comprising: generating personalization data specific to the at least one client devices; transmitting the data to the at least one client device; and establishing at least one security permission or policy within the at least one client device, the at least one permission or policy enabling provision of the requested service. 
     In one variant, the service request comprises part of a feature offered within only selected levels of a network operator service subscription plan. 
     In another variant, the service request comprises a request for download and distribution of protected content to a second device in data communication with the client device. The distribution of protected content to a second device in data communication with the client device comprises distribution of encrypted video content to the second device via e.g., a Firewire (IEEE-1394) interface. 
     Alternatively, distribution of protected content to a second device in data communication with the client device comprises distribution of encrypted video content to the mobile device via e.g., a WiFi (IEEE-802.11) interface. 
     In another variant, the act of generating personalization data comprises generating an encrypted software image and cryptographic key that is unique to the at least one client device. 
     In an eighth aspect of the invention, a method delivering secure software over a network to a remote client device is disclosed. In one embodiment, the method comprises: providing via a first entity device credentials along with the public key for the client device to a second entity; returning a client device-specific personalized software image to the first entity from the second entity; returning a common software image to the first entity from the second entity; encrypting at least the device-specific image for the specific client device based at least in part on the public key; and sending via the first entity the encrypted device-specific image and the common image. 
     In one variant, the first entity comprises an authentication proxy, and the second entity comprises a personalization server. The public key corresponds to a private key retained within the client device, the private key being adapted to decrypt the encrypted at least device-specific image. 
     In another variant, the common image comprises an image applicable to all of a plurality of client devices having a common configuration and disposed within the network, and the device-specific image is specific to only the remote client device. 
     In a ninth aspect of the invention, improved network apparatus for software downloading is disclosed. In one embodiment, the apparatus comprises: a common image server; and a device-specific image server. The apparatus is adapted to securely obtain and deliver a device-specific software image, as well as a common software image, to at least a target client device, the common image being applicable to all of a plurality of client devices having a common configuration and disposed within a network, and the device-specific image being specific to only the target client device. 
     In one variant, the apparatus is adapted to communicate over the network with a secure entity disposed on the target device, at least the device-specific image being adapted to run within a software environment of the secure entity in order to enforce one or more security policies within a domain associated with the target device. The network comprises a content-based delivery network, and the target device comprises an OCAP-compliant premises device having a cable modem and an RF tuner, the cable modem being used to receive at least a portion of the device-specific image. 
     In another variant, the content-based delivery network comprises a cable television network, and the cable modem comprises a DOCSIS gateway (DG) function having a plurality of individual logical tunnels associated therewith, at least one of the tunnels being used to deliver the at least a portion of the device-specific image. 
     In a tenth aspect of the invention, network apparatus for use in providing secure content and software downloads to a plurality of client devices within a cable television network is disclosed. In one embodiment, the apparatus comprises: secure download infrastructure adapted for data communication with a trusted authority (TA); a media provisioning system in data communication with the infrastructure; a billing system in data communication with the provisioning system; a media security system in data communication with the provisioning system; and a media services system in data communication with the provisioning system. The secure download infrastructure and the TA cooperate to provide cryptographic elements and at least one secure client device software image for delivery by the infrastructure to the client devices; and the provisioning system and the security system determine and apply entitlements for selected ones of the client device in order to authorize providing the cryptographic elements and the at least one software image thereto. 
     These and other aspects of the invention shall become apparent when considered in light of the disclosure provided herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a functional block diagram illustrating an exemplary HFC cable network configuration useful with the present invention. 
         FIG. 1 a    is a functional block diagram illustrating one exemplary HFC cable network head-end configuration useful with the present invention. 
         FIG. 1 b    is a functional block diagram illustrating one exemplary local service node configuration useful with the present invention. 
         FIG. 1 c    is a functional block diagram illustrating one exemplary broadcast switched architecture (BSA) network useful with the present invention. 
         FIG. 2  is a graphical representation of a generalized security management architecture according to the invention, comprising trusted authority, operator network, and user domains. 
         FIGS. 2 a -2 c    are functional block diagrams illustrating various configurations of the user domain of  FIG. 2 , including direct or indirect output to one or more secure output domains (SODs) and/or non-secure output domains (NSODs). 
         FIG. 3 a    is a functional block diagram of the secure download system (SDS) architecture configured in accordance with a first embodiment of the invention. 
         FIG. 3 b    is a functional block diagram of the secure download system (SDS) architecture configured in accordance with a second embodiment of the invention, including a trusted authority proxy (TAP). 
         FIG. 3 c    is a functional block diagram of the secure download system (SDS) architecture configured in accordance with a third embodiment of the invention, the network operator infrastructure disposed substantially within a BSA network hub site. 
         FIG. 3 d    is a functional block diagram of the secure download system (SDS) architecture configured in accordance with a fourth embodiment of the invention, the network operator infrastructure disposed substantially within a BSA network hub site and incorporating a trusted authority proxy (TAP). 
         FIG. 3 e    is a functional block diagram of one exemplary embodiment of the network operator infrastructure of the SDS architecture of  FIG. 3 a   , showing its relationship to other network system components. 
         FIG. 3 f    is a functional block diagram of one exemplary embodiment of the network operator infrastructure of the SDS architecture of  FIG. 3 e   , showing additional details thereof. 
         FIG. 3 g    is a graphical representation of one exemplary embodiment of the media security services portion of the network operator infrastructure of the SDS architecture of the invention. 
         FIG. 3 h    is a functional block diagram of one exemplary embodiment of cable television network head-end including the SDS architecture of the present invention. 
         FIG. 3 i    is a functional block diagram of one exemplary embodiment of cable television network having multiple network regions, including a distributed SDS, according to the invention. 
         FIG. 3 j    is a functional block diagram of one exemplary embodiment of the SDS architecture of the invention, showing secure and non-secure components and interfaces. 
         FIG. 3 k    is a logical block diagram of one exemplary embodiment of the authentication proxy (AP) of the SDS architecture of the invention, showing various messaging and interfaces to and from the AP. 
         FIG. 3 l    is a logical block diagram of one exemplary embodiment of the personalization server (PS) of the SDS architecture of the invention, showing various messaging and interfaces to and from the PS. 
         FIG. 3 m    is a logical block diagram of one exemplary embodiment of the local key server (LKS) of the SDS architecture of the invention, showing various messaging and interfaces to and from the LKS. 
         FIG. 3 n    is a logical block diagram of one exemplary embodiment of the SDS provisioning system (SPS), showing various messaging and interfaces to and from the SPS. 
         FIG. 3 o    is a logical flow diagram illustrating one exemplary embodiment of common and personalized software information exchange across the IXI software interface. 
         FIG. 4  is a graphical illustration of an exemplary embodiment of the generalized software architecture used to implement the security architecture of the invention. 
         FIG. 4 a    is a graphical illustration of an exemplary embodiment of the software architecture within the client device (e.g., CPE) used within the security architecture of the invention. 
         FIG. 4 b    is a graphical illustration of a DOCSIS gateway and tunnel architecture used in one exemplary embodiment of the security architecture of the invention. 
         FIG. 5  is a functional block diagram of one exemplary embodiment of the security-enabled client device (e.g., CPE) of the invention. 
         FIG. 6  is a logical flow diagram of one exemplary embodiment of the generalized method of conditional access (CA), trusted domain (TD), and/or digital rights management (DRM) configuration and update using the secure download system of the invention. 
         FIG. 6 a    is a logical flow diagram of one exemplary embodiment of the generalized method of Fig., illustrated in the context of a conditional access (CA) system of a cable television network 
         FIG. 6 b    is a logical flow diagram of one exemplary embodiment of the protocol utilized in order to protect content and keys, and selectively allow access to encrypted content. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is now made to the drawings wherein like numerals refer to like parts throughout. 
     As used herein, the term “application” refers generally to a unit of executable software that implements a certain functionality or theme. The themes of applications vary broadly across any number of disciplines and functions (such as on-demand content management, e-commerce transactions, brokerage transactions, home entertainment, calculator etc.), and one application may have more than one theme. The unit of executable software generally runs in a predetermined environment; for example, the unit could comprise a downloadable Java Xlet™ that runs within the JavaTV™ environment. 
     As used herein, the terms “client device” and “end user device” include, but are not limited to, set-top boxes (e.g., DSTBs), personal computers (PCs), and minicomputers, whether desktop, laptop, or otherwise, and mobile devices such as handheld computers, PDAs, personal media devices (PMDs), such as for example an iPod™, or Motorola ROKR, and smartphones. 
     As used herein, the term “codec” refers to an video, audio, or other data coding and/or decoding algorithm, process or apparatus including, without limitation, those of the MPEG (e.g., MPEG-1, MPEG-2, MPEG-4, etc.), Real (RealVideo, etc.), AC-3 (audio), DiVX, XViD/ViDX, Windows Media Video (e.g., WMV 7, 8, or 9), ATI Video codec, or VC-1 (SMPTE standard 421M) families. 
     As used herein, the term “computer program” or “software” is meant to include any sequence or human or machine cognizable steps which perform a function. Such program may be rendered in virtually any programming language or environment including, for example, C/C++, Fortran, COBOL, PASCAL, assembly language, markup languages (e.g., HTML, SGML, XML, VoXML), and the like, as well as object-oriented environments such as the Common Object Request Broker Architecture (CORBA), Java™ (including J2ME, Java Beans, etc.), Binary Runtime Environment (BREW), and the like. 
     As used herein, the term “conditional access” refers to any access control scheme, whether implemented in hardware, software, or firmware (or combinations thereof), including without limitation members of the “Powerkey” family, NDS (including VideoGuard, mVideoGuard, etc.), DVB, and Motorola/General Instrument DigiCipher® family (DigiCipher II, etc.). These can be implemented using, for example, CA-specific hardware/software elements embedded in the device, the so-called “CableCard” plug-in security module access technology, a downloadable CA system (DCAS), or otherwise. 
     The terms “Customer Premises Equipment (CPE)” and “host device” refer to any type of electronic equipment located within a customer&#39;s or user&#39;s premises and connected to a network. The term “host device” refers generally to a terminal device that has access to digital television content via a satellite, cable, or terrestrial network. The host device functionality may be integrated into a digital television (DTV) set. The term “customer premises equipment” (CPE) includes such electronic equipment such as set-top boxes (e.g., DSTBs), televisions, cable modems (CMs), embedded multimedia terminal adapters (eMTAs), whether stand-alone or integrated with other devices, Digital Video Recorders (DVR), gateway storage devices (Furnace), and ITV Personal Computers. 
     As used herein, the term “database” refers generally to one or more tangible or virtual data storage locations, which may or may not be physically co-located with each other or other system components. 
     As used herein, the term “display” means any type of device adapted to display information, including without limitation CRTs, LCDs, TFTs, plasma displays, LEDs, incandescent and fluorescent devices. Display devices may also include less dynamic devices such as, for example, printers, e-ink devices, and the like. 
     As used herein, the term “DVI” (digital video interface) refers generally to any type of interface (e.g., hardware and/or software) adapted to provide interface and/or conversion between different formats or domains, including without limitation interfaces compliant with the Digital Display Working Group (DDWG) DVI specification (e.g., DVI-A, DVI-D, and DVI-I). For example, using a DVI connector and port, a digital signal sent to an analog monitor is converted into an analog signal; if the monitor is digital, such as a flat panel display, no conversion is necessary. A DVI output is an option in OpenCable compliant hardware that provides a high-definition TV (HDTV) output which includes copy protection. 
     As used herein, the term “DVR” (digital video recorder) refers generally to any type or recording mechanism and/or software environment whereby content sent over a network can be recorded and selectively recalled. Such DVR may be dedicated in nature, or part of a non-dedicated or multi-function system. 
     As used herein, the term “DOCSIS” refers to any of the existing or planned variants of the Data Over Cable Services Interface Specification, including for example DOCSIS versions 1.0, 1.1, 2.0 and 3.0. DOCSIS (version 1.0) is a standard and protocol for internet access using a “digital” cable network. DOCSIS 1.1 is interoperable with DOCSIS 1.0, and has data rate and latency guarantees (VoIP), as well as improved security compared to DOCSIS 1.0. DOCSIS 2.0 is interoperable with 1.0 and 1.1, yet provides a wider upstream band (6.4 MHz), as well as new modulation formats including TDMA and CDMA. It also provides symmetric services (30 Mbps upstream). 
     As used herein, the term “head-end” refers generally to a networked system controlled by an operator (e.g., an MSO) that distributes programming to MSO clientele using client devices. Such programming may include literally any information source/receiver including, inter alia, free-to-air TV channels, pay TV channels, interactive TV, and the Internet. DSTBs may literally take on any configuration, and can be retail devices meaning that consumers may or may not obtain their DSTBs from the MSO exclusively. Accordingly, it is anticipated that MSO networks may have client devices from multiple vendors, and these client devices will have widely varying hardware capabilities. Multiple regional head-ends may be in the same or different cities. 
     As used herein, the term “integrated circuit (IC)” refers to any type of device having any level of integration (including without limitation ULSI, VLSI, and LSI) and irrespective of process or base materials (including, without limitation Si, SiGe, CMOS and GaAs). ICs may include, for example, memory devices (e.g., DRAM, SRAM, DDRAM, EEPROM/Flash, ROM), digital processors, SoC devices, FPGAs, ASICs, ADCs, DACs, transceivers, memory controllers, and other devices, as well as any combinations thereof. 
     As used herein, the terms “Internet” and “internet” are used interchangeably to refer to inter-networks including, without limitation, the Internet. 
     As used herein, the term “memory” includes any type of integrated circuit or other storage device adapted for storing digital data including, without limitation, ROM. PROM, EEPROM, DRAM, SDRAM, DDR/2 SDRAM, EDO/FPMS, RLDRAM, SRAM, “flash” memory (e.g., NAND/NOR), and PSRAM. 
     As used herein, the terms “microprocessor” and “digital processor” are meant generally to include all types of digital processing devices including, without limitation, digital signal processors (DSPs), reduced instruction set computers (RISC), general-purpose (CISC) processors, microprocessors, gate arrays (e.g., FPGAs), PLDs, reconfigurable compute fabrics (RCFs), array processors, secure microprocessors, and application-specific integrated circuits (ASICs). Such digital processors may be contained on a single unitary IC die, or distributed across multiple components. 
     As used herein, the terms “MSO” or “multiple systems operator” refer to a cable, satellite, or terrestrial network provider having infrastructure required to deliver services including programming and data over those mediums. 
     As used herein, the terms “network” and “bearer network” refer generally to any type of telecommunications or data network including, without limitation, hybrid fiber coax (HFC) networks, satellite networks, telco networks, and data networks (including MANs, WANs, LANs, WLANs, internets, and intranets). Such networks or portions thereof may utilize any one or more different topologies (e.g., ring, bus, star, loop, etc.), transmission media (e.g., wired/RF cable, RF wireless, millimeter wave, optical, etc.) and/or communications or networking protocols (e.g., SONET, DOCSIS, IEEE Std. 802.3, ATM, X.25, Frame Relay, 3GPP, 3GPP2, WAP, SIP, UDP, FTP, RTP/RTCP, H.323, etc.). 
     As used herein, the terms “network agent” and “network entity” refers to any network entity (whether software, firmware, and/or hardware based) adapted to perform one or more specific purposes. For example, a network agent or entity may comprise a computer program running in server belonging to a network operator, which is in communication with one or more processes on a CPE or other device. 
     As used herein, the term “node” refers without limitation to any location, functional entity, or component within a network. 
     As used herein, the term “QAM” refers to modulation schemes used for sending signals over cable networks. Such modulation scheme might use any constellation level (e.g. QPSK, QAM-16, QAM-64, QAM-256 etc.) depending on details of a cable network. A QAM may also refer to a physical channel modulated according to said schemes. 
     As used herein, the term “network interface” refers to any signal, data, or software interface with a component, network or process including, without limitation, those of the Firewire (e.g., FW400, FW800, etc.), USB (e.g., USB2), Ethernet (e.g., 10/100, 10/100/1000 (Gigabit Ethernet), 10-Gig-E, etc.), MoCA, Serial ATA (e.g., SATA, e-SATA, SATAII), Ultra-ATA/DMA, Coaxsys (e.g., TVnet™), radio frequency tuner (e.g., in-band or OOB, cable modem, etc.), WiFi (802.11a,b,g,n), WiMAX (802.16), PAN (802.15), or IrDA families. 
     As used herein, the term “personalization” refers generally and without limitation to data, cryptographic elements, and/or code downloaded or otherwise provided to a target device or domain (e.g., host) to create a desired security environment or policies for operation on or with a particular network system. 
     As used herein, the term “server” refers to any computerized component, system or entity regardless of form which is adapted to provide data, files, applications, content, or other services to one or more other devices or entities on a computer network. 
     As used herein, the term “user interface” refers to, without limitation, any visual, graphical, tactile, audible, sensory, or other means of providing information to and/or receiving information from a user or other entity. 
     As used herein, the term “WiFi” refers to, without limitation, any of the variants of IEEE-Std. 802.11 or related standards including 802.11 a/b/g/n. 
     As used herein, the term “wireless” means any wireless signal, data, communication, or other interface including without limitation WiFi, Bluetooth, 3G, HSDPA/HSUPA, TDMA, CDMA (e.g., IS-95A, WCDMA, etc.), FHSS, DSSS, GSM, PAN/802.15, WiMAX (802.16), 802.20, narrowband/FDMA, OFDM, PCS/DCS, analog cellular, CDPD, satellite systems, millimeter wave or microwave systems, acoustic, and infrared (i.e., IrDA). 
     Overview 
     In one salient aspect, the present invention comprises a network architecture that provides for enhanced conditional access (CA), trusted domain (TD), and digital rights management (DRM) capabilities. This network architecture comprises apparatus useful at, inter alia, the head-end or distribution hub of a cable network, for implementing a download paradigm for legacy or newly developed CA, TD, and DRM software and cryptographic protection schemes. This allows the network operator, and even the third party content provider by proxy, to exert additional control on viewing, reproduction, and migration of content distributed over the network. 
     In one embodiment, these enhanced capabilities comprise downloadable software modules (images), and an associated decryption key that facilitates decryption of the downloaded software images. In contrast to prior art approaches of merely encrypting the content itself (such as via a DES or AES algorithm via a symmetric or asymmetric key approach), the exemplary embodiments of the present invention allow for the download of secure software images, which may be used to, inter alia, ensure security of the downloaded images and also migrate protected content to other platforms in the user or client domain so as to extend the “trusted domain”. 
     Advantageously, the architecture of the present invention provides for securing of the CA, TD, and DRM Client software as opposed to merely the delivered content. Specifically, outside of the conditional access system (CAS), the software of the present invention is never rendered in an unprotected form or otherwise made accessible. This is of particular significance from the standpoint that protection of the software is typically of much greater commercial interest and value to the network operator than the content itself. Stated differently, not only is the delivered content highly secure, but also the mechanisms used to control and access the content within the user domain. 
     Other benefits of the “download” approach described herein include: (i) operation with both new and legacy CAS systems including DVB-CSA CAS proprietary systems; (ii) ability to be readily integrated with retail and OEM products; (iii) reduction of security costs associated with CAS implementation (i.e., by avoiding the capital expenditures and operating costs associated with purchasing, installing and maintaining CableCards or similar implementations); use of state-of-the-art security hardware and software, thereby enhancing protection of MSO and third party content provider investments; (v) centralized control of key generation and distribution by network operators (e.g., MSO&#39;s); and (vi) flexibility that allows for deployment of broadcast, VOD, TD, and DRM security solutions from multiple vendors. 
     Moreover, the secure download approach of the present invention allows for ready implementation of future security upgrades such as improved encryption algorithms and new CAS, TD, or DRM technologies. 
     Another primary feature of the secure download architecture of the present invention is the creation of a system that is substantially consistent or symmetric with respect to both leased and retail client devices or CPE. Devices that are connected to the operator&#39;s network utilize a prescribed process to ensure that the client device&#39;s download “host” has the correct software and cryptographic elements (e.g., keying) for operation on that network, regardless of whether the device comprises a lease or retail installation. The exemplary processes described herein advantageously cause client device hosts with inappropriate or no such software or cryptographic elements to acquire these components from the network securely. This approach allows for substantial ubiquity for both leased and retail devices on the network, and at a competitive cost. 
     The secure download architecture of the present invention can serve a variety of security environments and configurations ranging from the most basic (e.g., a low-end digital video service), to a high-end, multi-play environment with digital video, digital recording, multimedia, and data services. These environments can also include the ability to decrypt video delivered by the MSO, encrypt and decrypt content stored onto or retrieved from a hard drive (e.g., for PVR devices which require DRM), and decrypt and encrypt content delivered to or being sent from the TD. 
     In the exemplary embodiment, the network portion of the architecture (disposed, e.g., the cable network head-end or BSA hub) comprises an authentication proxy (AP), conditional access (CA) system, and media provisioning system (MPS). A personalization server (PS) is used in conjunction with the system to provide “personalization” to the client device(s), including providing the aforementioned software and cryptographic element (e.g., key) management download functions previously described. The aforementioned network portion of the architecture provides other security features as well, including client device and network authentication, and processing of security services (e.g., for OCAP applications in the exemplary cable television network context). 
     An exemplary security download and initiation protocol consisting of a series of messages that are used to, inter alia, (i) identify, (ii) authenticate, (iii) download, (iv) install, (v) run, and (vi) monitor the installation and status of, the secure image on the CPE are also described. 
     Detailed Description of Exemplary Embodiments 
     Exemplary embodiments of the apparatus and methods of the present invention are now described in detail. While these exemplary embodiments are described in the context of the aforementioned hybrid fiber coax (HFC) cable system architecture having an multiple systems operator (MSO), digital networking capability, and plurality of client devices/CPE, the general principles and advantages of the invention may be extended to other types of networks and architectures, whether broadband, narrowband, wired or wireless, or otherwise, the following therefore being merely exemplary in nature. 
     It will also be appreciated that while described generally in the context of a consumer (i.e., home) end user domain, the present invention may be readily adapted to other types of environments (e.g., commercial/enterprise, government/military, etc.) as well. Myriad other applications are possible. 
     It is further noted that while described primarily in the context of a cable system with 6 MHz RF channels, the present invention is applicable to literally any network topology or paradigm, and any frequency/bandwidth, such as for example 8 MHz channels. Furthermore, as referenced above, the invention is in no way limited to traditional cable system frequencies (i.e., below 1 GHz), and in fact may be used with systems that operate above 1 GHz band in center frequency or bandwidth, to include without limitation so-called ultra-wideband systems. 
     Also, while certain aspects are described primarily in the context of the well-known Internet Protocol (described in, inter alia, RFC 791 and 2460), it will be appreciated that the present invention may utilize other types of protocols (and in fact bearer networks to include other internets and intranets) to implement the described functionality. 
     Network— 
       FIG. 1  illustrates a typical content-based network configuration with which the secure download apparatus and methods of the present invention may be used. The various components of the network  100  include (i) one or more data and application origination points  102 ; (ii) one or more content sources  103 , (iii) one or more application distribution servers  104 ; (iv) one or more VOD servers  105 , and (v) consumer premises equipment (CPE)  106 . The distribution server(s)  104 , VOD servers  105  and CPE(s)  106  are connected via a bearer (e.g., HFC) network  101 . A simple architecture comprising one of each of the aforementioned components  102 ,  104 ,  105 ,  106  is shown in  FIG. 1  for simplicity, although it will be recognized that comparable architectures with multiple origination points, distribution servers, VOD servers, and/or CPE devices (as well as different network topologies) may be utilized consistent with the invention. For example, the head-end architecture of  FIG. 1 a    (described in greater detail below) may be used. 
     The data/application origination point  102  comprises any medium that allows data and/or applications (such as a VOD-based or “Watch TV” application, or other application) to be transferred to a distribution server  104 . This can include for example a third party data source, application vendor website, CD-ROM, external network interface, mass storage device (e.g., RAID system), etc. Such transference may be automatic, initiated upon the occurrence of one or more specified events (such as the receipt of a request packet or ACK), performed manually, or accomplished in any number of other modes readily recognized by those of ordinary skill. 
     The application distribution server  104  comprises a computer system where such applications can enter the network system. Distribution servers are well known in the networking arts, and accordingly not described further herein. 
     The VOD server  105  comprises a computer system where on-demand content can be received from one or more of the aforementioned data sources  102  and enter the network system. These servers may generate the content locally, or alternatively act as a gateway or intermediary from a distant source. 
     The CPE  106  includes any equipment in the “customers&#39; premises” (or other locations, whether local or remote to the distribution server  104 ) that can be accessed by a distribution server  104  or other network entity. Exemplary embodiments of the CPE of the invention are described subsequently herein with respect to  FIG. 5 . 
     Referring now to  FIG. 1 a   , one exemplary embodiment of a generic network head-end architecture useful with the present invention is described. As shown in  FIG. 1 a   , the head-end architecture  150  comprises typical head-end components and services including billing module  152 , subscriber management system (SMS) and CPE configuration management module  154 , cable-modem termination system (CMTS) and OOB system  156 , as well as LAN(s)  158 ,  160  placing the various components in data communication with one another. It will be appreciated that while a bar or bus LAN topology is illustrated, any number of other arrangements as previously referenced (e.g., ring, star, etc.) may be used consistent with the invention. It will also be appreciated that the head-end configuration depicted in  FIG. 1 a    is high-level, conceptual architecture and that each MSO may have multiple head-ends deployed using custom architectures (see, e.g.,  FIGS. 3 e -3 n    and associated discussion presented subsequently herein). 
     The architecture  150  of  FIG. 1 a    further includes a multiplexer/encrypter/modulator (MEM)  162  coupled to the HFC network  101  adapted to “condition” content for transmission over the network. The distribution servers  104  are coupled to the LAN  160 , which provides access to the MEM  162  and network  101  via one or more file servers  170 . The VOD servers  105  are coupled to the LAN  160  as well, although other architectures may be employed (such as for example where the VOD servers are associated with a core switching device such as an 802.3z Gigabit Ethernet device). As previously described, information is carried across multiple channels. Thus, the head-end must be adapted to acquire the information for the carried channels from various sources. Typically, the channels being delivered from the head-end  150  to the CPE  106  (“downstream”) are multiplexed together in the head-end and sent to neighborhood hubs ( FIG. 1 b   ) via a variety of interposed network components. 
     Content (e.g., audio, video, etc.) is provided in each downstream (in-band) channel associated with the relevant service group. To communicate with the head-end or intermediary node (e.g., hub server), the CPE  106  may use the out-of-band (OOB) or DOCSIS channels and associated protocols. The OCAP 1.0, 2.0, 3.0 (and subsequent) specifications provide for exemplary networking protocols both downstream and upstream, although the invention is in no way limited to these approaches. 
     It will also be recognized that the multiple servers (broadcast, VOD, or otherwise) can be used, and disposed at two or more different locations if desired, such as being part of different server “farms”. These multiple servers can be used to feed one service group, or alternatively different service groups. In a simple architecture, a single server is used to feed one or more service groups. In another variant, multiple servers located at the same location are used to feed one or more service groups. In yet another variant, multiple servers disposed at different location are used to feed one or more service groups. 
     As shown in  FIG. 1 b   , the network  101  of  FIGS. 1 and 1   a  comprises a fiber/coax arrangement wherein the output of the MEM  162  of  FIG. 1 a    is transferred to the optical domain (such as via an optical transceiver  177  at the head-end or further downstream). The optical domain signals are then distributed to a fiber node  178 , which further distributes the signals over a distribution network  180  to a plurality of local servicing nodes  182 . This provides an effective 1:N expansion of the network at the local service end. 
     “Switched” Networks— 
       FIG. 1 c    illustrates an exemplary “switched” network architecture also useful with the secure download system (SDS) of the present invention. While a so-called “broadcast switched architecture” or BSA network is illustrated in this exemplary embodiment, it will be recognized that the present invention is in no way limited to such architectures. 
     Switching architectures allow improved efficiency of bandwidth use for ordinary digital broadcast programs. Ideally, the subscriber will be unaware of any difference between programs delivered using a switched network and ordinary streaming broadcast delivery. 
       FIG. 1 c    shows the implementation details of one exemplary embodiment of this broadcast switched network architecture. Specifically, the head-end  150  contains switched broadcast control and media path functions  190 ,  192 ; these element cooperating to control and feed, respectively, downstream or edge switching devices  194  at the hub site which are used to selectively switch broadcast streams to various service groups. A BSA server  196  is also disposed at the hub site, and implements functions related to switching and bandwidth conservation (in conjunction with a management entity  198  disposed at the head-end). An optical transport ring  197  is utilized to distribute the dense wave-division multiplexed (DWDM) optical signals to each hub in an efficient fashion. 
     Co-owned and co-pending U.S. patent application Ser. No. 09/956,688 filed Sep. 20, 2001 and entitled “Technique For Effectively Providing Program Material In A Cable Television System”, incorporated herein by reference in its entirety, describes one exemplary broadcast switched digital architecture useful with the present invention, although it will be recognized by those of ordinary skill that other approaches and architectures may be substituted. 
     In addition to “broadcast” content (e.g., video programming), the systems of  FIGS. 1 a -1 c    also deliver Internet data services using the Internet protocol (IP), although other protocols and transport mechanisms of the type well known in the digital communication art may be substituted. One exemplary delivery paradigm comprises delivering MPEG-based video content, with the video transported to user PCs (or IP-based STBs) over the aforementioned DOCSIS channels comprising MPEG (or other video codec such as H.264 or AVC) over IP over MPEG. That is, the higher layer MPEG- or other encoded content is encapsulated using an IP protocol, which then utilizes an MPEG packetization of the type well known in the art for delivery over the RF channels. In this fashion, a parallel delivery mode to the normal broadcast delivery exists; i.e., delivery of video content both over traditional downstream QAMs to the tuner of the user&#39;s STB or other receiver device for viewing on the television, and also as packetized IP data over the DOCSIS QAMs to the user&#39;s PC or other IP-enabled device via the user&#39;s cable modem. 
     Referring again to  FIG. 1 c   , the IP packets associated with Internet services are received by edge switch  194 , and forwarded to the cable modem termination system (CMTS)  199 . The CMTS examines the packets, and forwards packets intended for the local network to the edge switch  194 . Other packets are discarded or routed to another component. 
     The edge switch  194  forwards the packets receive from the CMTS  199  to the QAM modulator  189 , which transmits the packets on one or more physical (QAM-modulated RF) channels to the CPEs. The IP packets are typically transmitted on RF channels that are different that the RF channels used for the broadcast video and audio programming, although this is not a requirement. The CPE  106  are each configured to monitor the particular assigned RF channel (such as via a port or socket ID/address, or other such mechanism) for IP packets intended for the subscriber premises/address that they serve. 
     Network Security Download Apparatus and Methods— 
     Referring now to  FIG. 2 , a generalized model of the security download architecture useful with the present invention is described. As used herein, the term “security architecture” is meant to encompass an environment adapted to accommodate at least: (i) CA requirements and policies; (ii) TD requirements and policies; and/or (iii) DRM requirements and policies. For the sake of illustration, exemplary embodiments of the architecture will be described primarily in terms of a conditional access (CA) security environment, although the principles described are readily adapted to DRM and TD applications as well. 
     Moreover, while many of the exemplary embodiments describe obtaining information from a head-end server, TA, or other such entity, the present invention also contemplates the use of other sources of such information including, without limitation, peer devices within or outside of the network, or intermediary nodes in the content distribution network. 
     As shown in  FIG. 2 , this generalized model  200  comprises three primary domains; i.e., (1) a trust authority domain  202 ; (2) a network operator domain  204 ; and (3) a user domain  206 . Various entities within these domains are in communication with one another in order to effectuate the desired functions of the downloadable CA (e.g., “DCAS”), TD, and/or DRM environments. 
     Central to the present invention is the concept of a “trusted domain” or TD. As previously described, such a “trusted domain” (TD) comprises an area (physically or virtually) within which programming or other content is protected from unauthorized access, distribution and copying. For example, in a cable network, a trusted domain may include not only the network portion where programming content traditionally is secured by, and within total control of, a cable operator (including, e.g., the head-end  150 , HFC delivery network  101 , etc.,) but also user devices or CPE  106  at subscribers&#39; premises which are capable of receiving and securely storing programming content. Using the trusted domain approach, the network operator can guarantee certain subscriber access, distribution, and usage policy enforcement with respect to content held within the domain. For example, a digital representation of a movie held within an operator&#39;s TD (e.g., on a hard drive of a user device) cannot be distributed over the Internet, wireless network, etc. in viewable form, and cannot become a source for duplication of multiple viewable copies. 
     Exemplary apparatus and methods for implementing a “trusted domain” are described in co-owned and co-pending U.S. patent application Ser. No. 11/006,404 previously incorporated herein, although it will be appreciated that other approaches may be used with equal success consistent with the present invention. 
     In another variant of the invention the TD comprises a so-called “authorized service domain” or ASD. One exemplary embodiment of an authorized service domain useful with this variant is described in the document “DCAS Authorized Service Domain”, Version 1.2, dated Nov. 30, 2005, which is incorporated herein by reference in its entirety. In this embodiment, the ASD comprises a domain where content is secured using the mechanisms available through the operator&#39;s conditional access system. For example, in a subscriber&#39;s home, the ASD physically translates into a collection of one or more trusted devices where content may be securely stored and moved within the domain. The distinction between the exemplary ASD and other forms of copy protection (e.g., DTCP) relates primarily to the fact that the content remains under operator control at all times. The control point within the ASD is the personalized secure microprocessor (SM). Hence, the ASD acts effectively as an extension of the operator&#39;s Conditional Access (CA) system. 
     It will be recognized that on the client side, the TD established within a target device (e.g., CPE  106 ) is not necessarily coextensive with the CPE  106  itself. For example, only certain portions of the CPE will be secure and suitable for maintaining the integrity of the protected content, and others (such as the analog output interface to a non-protected output domain or NSOD as described subsequently herein) not comprising part of the TD. 
     Referring again to  FIG. 2 , the trusted authority domain  202  generally comprises a Trusted Authority (TA)  203 . The TA provides a secure keying and programming environment for selected client devices on the network. The Trusted Authority tracks and communicates keys and keying information for all authorized download system components. 
     The network operator domain  204  generally comprises an authentication proxy (AP)  208  or agent  208 , which communicates with the TA  203  in order to authenticate itself, and obtain the aforementioned keys and information that that is required to authenticate itself to the secure microprocessor (SM) described subsequently herein. The AP also communicates with the user domain  206  (e.g., with the secure download system (SDS) host  210  in the client device) in order to authenticate the client device (host) and download secure software images and cryptographic elements (e.g., keys) used in establishing the security domain and policies within the client device. 
     The user domain  206  comprises for example a user premises (e.g., residence or enterprise), including the user&#39;s host  210  and client device or CPE  106 . Note that the SDS host  210  comprises a network security “entity” that may be coincident or separate from the physical implementation of the client device  106 ; the two may not be coextensive. For example, the host  210  may generically include the CPE  106  and any other devices that are compliant to the security download specifications and requirements. 
     The client device may take any number of forms, including for example a set-top box (e.g., DSTB), a converged device or “hive” such as that described in co-pending U.S. patent application Ser. No. 11/378,129 filed Mar. 16, 2006 entitled “Methods And Apparatus For Centralized Content And Data Delivery”, incorporated herein by reference in its entirety, a wireless satellite receiver, or even a mobile wireless device in direct or indirect data communication with the operator network domain  204  and the AP  208 . See, e.g., co-owned and co-pending U.S. patent application Ser. No. 11/258,229 entitled “Method And Apparatus For On-Demand Content Transmission And Control Over Networks” filed Oct. 24, 2005, incorporated herein by reference in its entirety, wherein media can be streamed between a mobile unit and user CPE  106 , including optionally in an on-demand or session-based fashion. Accordingly, the present invention contemplates that the trusted domain and CA/DRM control can be exterted over several interconnected networks, including those outside of the MSO or user domain (e.g., a WSP or CSP network and radio area network (RAN) associated with the mobile device). 
     Similarly, so called “personal media devices” (PMDs) are contemplated to be used to form part of the trusted domain within the user domain. In one exemplary embodiment, the PMD comprises a video or other personal media device having multimedia capability, and which can include a secure microprocessor (SM) and other necessary components to authenticate to the CPE (acting as an AP proxy) or directly with the AP  208 , and receive CA/DRM/TD client images as well as cryptographic elements such as secure microprocessor encryption or signaling keys (SMEK and SMSK). For example, the PMD could act as either a) another DCAS device to which individual clients could be downloaded, or b) an acceptable trusted domain interface that allows TD content to be played on the player of the PMD. 
     In one variant, the user domain  206  of  FIG. 2  comprises a residence. In addition to or in place of a traditional CAT-5 Ethernet twisted pair wiring configuration, the user&#39;s indigenous residence coaxial cabling, telephone wiring, or even low-frequency electrical wiring (e.g., HomePlug) may be used as a basis of forming a LAN within the residence. Similarly, the client device (or apparatus in communication therewith) may comprise a wireless interface or gateway, so that residence users are free to “roam” within or even outside the residence while maintaining connectivity to the MSO network. As will be described below in greater detail, the secure or “trusted” domain established by the present invention within the user premises may extend to devices which are not physically connected to the CPE  106  or other client device that is in direct communication with the AP. This underscores on salient advantage of the present invention over prior art CA and similar network security systems; i.e., the ability to extend the domain within which the protected content may safely reside outside of the CPE  106  itself, thereby giving the user and network operator significant flexibility in providing new and enhanced services and features without jeopardizing content security. 
     It will be recognized that while the user domain  206  of  FIG. 2  is illustrated as a generally fixed, single location, the user domain according to the present invention may in fact: (i) comprise multiple different physical locations, such as for example in the case of an enterprise, wherein the host device  210  acts as a gateway to a premises network  212  (e.g., corporate LAN, WAN, internet) serving multiple different locations or offices of that enterprise. Furthermore, these one or more locations need not be fixed, but rather may also vary as a function of time. For example, as previously described, the host  210  may act as a portal or gateway to a wireless network (e.g., WiFi, WiMax, etc.) that places the user(s), e.g., members of a given family in communication with the host  210  via their mobile wireless devices. A cable modem (e.g., DOCSIS) may also be used to provide internet connectivity to the premises (and hence the host  210 ), such that remote users/family members can access the host, and even devices connected thereto (such as DVRs, etc.) via their internet connection (at a remote site) and via the cable modem. 
     In another embodiment of the of the user domain, a personal video encoder (PVE) or comparable device is used as part of or is in communication with the DCAS host  210  (or an associated client device coupled thereto). For example, the “Slingbox” device manufactured by Sling Media of San Mateo, Calif. is one such exemplary device which is capable of enabling a user to watch TV programming from various locations via an Internet-connected PC or similar device. The device is generally connected between the subscriber&#39;s cable/satellite video drop and DSTB, and has a TV tuner inside. The user tunes to a given channel, and the device encodes the video streamed over the cable/satellite in Windows Media or similar format. The encoded content is streamed to a client application on a TD-enabled Windows XP-based or similar PC via an IP network such as the Internet, and hence the user can view the data locally (i.e., at the same premises) or remotely so long as they have access to the IP distribution network. This functionality can be made part of a separate physical component within the user domain  206 , or alternatively have some or all of its functionality disposed within the client device or CPE  106  itself. It may also be integrated with other devices (such as connected client devices or PMDs) as previously noted. 
     As can be appreciated, literally an unlimited number of network topologies (whether mobile, fixed, or both) may be used consistent with the aim of extending or configuring the trusted portion of the user domain  206 . 
     The user domain  206  also typically will include one or more output devices  214 , e.g., television monitors, personal computers, and the like. These devices will typically carry no security or protection mechanisms to protect content, and hence are not typically part of the “trusted domain”, but rather a non-secure output domain (NSOD) as described in greater detail subsequently herein. These devices&#39; may, however, by physically integrated with a device that is part of the trusted domain, such as wherein a monitor is combined with a DVR, DSTB, or PC. 
     In the exemplary trusted domain architecture, content is secured using mechanisms specified and provided by the network operator. The TD can also be used to implement and manage selective control of output to one or more output domains (ODs). These ODs can be considered as being outside of the TD, yet which implement prescribed security policies or mechanisms. For example, one such OD may comprise a secure OD (SOD), wherein content delivered into the domain is protected using an authorized security mechanism that is outside of the network operator&#39;s direct control (in contrast to the TD, which is entirely with the operator&#39;s control). For example, the well known Digital Transmission Content Protection (DTCP) and High-Bandwidth Digital Content Protection (HDCP) copy protection schemes proffered by 5C and Intel Corporation, respectively. Literally any number of different DRM and copy protection techniques may be used (alone or in combination) consistent with the SOD of the present invention, however, including without limitation steganographics such as watermarking and encryption. 
     In the exemplary configuration, the network operator or designated third party proxy has the ability to specify policies to be implemented within the domain (e.g., copy one generation), via e.g., copy control information (CCI) or other such downstream communications to the host  210 . Hence, while the operator can specify security policies to be enforced within the SOD, access to content once it is within the SOD is not dependent on the operator&#39;s TD or CA system, but rather on the security mechanisms enforced within the SOD. This is in effect an “indirect” form of control by the operator on the SOD, without directly imposing CA or other such policies enforced within the TD. 
     Aside from the SOD, other forms of output domains (OD) may be utilized consistent with the invention. For example, in one variant, a non-secure OD (NSOD) is utilized. The NSOD literally may carry no protections or guarantees of the security for the content. For example, content output via an unprotected digital or analog interface (e.g., analog video output to a monitor or recording device) would be within the NSOD. Similarly, digital data transmitted “in the clear” would be entering an NSOD. 
     It will be appreciated that multiple SOD and/or NSOD domains can be cascaded according to the invention. For example,  FIG. 2 a    shows one embodiment of a cascaded homogeneous domain comprising: (i) the TD  252 ; (ii) a first SOD  254 , and (iii) a second (and subsequent) SOD  256  in data communication with the first SOD. To the degree that the first SOD  254  acts as a pass-through entity or proxy for the second SOD, the TD  252  can communicate with the second SOD  256  to verify that the second SOD meets the required security policies and protections, or alternatively the two SODs have previously agreed exchange rules and do not require pass-through of control. 
     Alternatively, a shown in  FIG. 2 b   , the cascade may be heterogeneous (i.e., with a SOD  254  in communication with the TD  252 , and one or more NSODs  260  in communication with the SOD  254 . However, it will be appreciated that an NSOD  260  generally cannot be interposed between a TD and a SOD with any confidence. 
     The trusted domain may also interface directly with both NSODs and SODs, as shown in  FIG. 2   c.    
     Moreover, a multi-layered rights management architecture useful to prevent unauthorized use and transfer of protected content within the user domain can be used consistent with the aforementioned SODs/NSODs of the present invention. 
     Referring now to  FIG. 3 a   , a first embodiment of the generalized secure download system (SDS) architecture including network operator domain  204  of the type shown in  FIG. 2  is described. As illustrated in  FIG. 3 , the exemplary architecture  300  comprises an authentication proxy (AP)  208 , conditional access system (CAS)  304  (including associated personalization server  306 ), and media (e.g., video) provisioning system  308 . These components are in communication with one another for performing various functions related to the security download system (SDS) architecture, as will be described in greater detail subsequently herein. A common image is present on the CAS  304 , while a user-domain specific or unique image (personalization portion) resides on the personalization server  306 . The unique image is specific to a given CPE or PMD using, e.g., a public/private key pair for security functions which may include CA, DRM or TD establishment and management. Each CA system  304  interacts with the AP  208  (via the PS  306 ) to provide personalized SM Client images for download into the SDS host  210 . The CA system  304  securely generates a common SM Client image which is downloaded by all SMs  514  sharing a common hardware and software configuration. In contrast, the personalized image is specific to a given host  210  (specifically, its SM  514 ). Note, however, that the CA image can be repurposed to a different SM if desired. 
     Communications between these entities  208 ,  304 ,  306  can be via any number of well known wired or wireless interfaces including, without limitation, Ethernet/GBE/10-Gig-E (e.g., 10/100/1000/10,000) LAN, IEEE-1394 (“Firewire”), USB, WiFi, UWB, and so forth. One or more intermediary agents or processes may also be interposed, such as where an indirect network path is used (e.g., router, gateway, portal, etc.). These communication paths may also be made physically secure (i.e., physically protected against surreptitious access by a third party), and/or or virtually secure (e.g., using VPN session or other higher layer processes “tunneled” or transmitted across an unsecure or untrusted physical medium, authentication, encryption, etc.). The well known 802.1x and WEP/WPA technologies can also be utilized in conjunction with a RADIUS server, as can any other protocols and security features well known to those of ordinary skill. 
     While shown being physically disposed at the head-end  150  of the exemplary MSO network, it will be appreciated that one or more of these components  208 ,  304 ,  306  (and/or their associated logical processes) can be disposed at other locations. Under certain deployment scenarios, a subset of SDS infrastructure components may be located at a centralized national site for each network operator. This allows for efficient centralization of operations and consideration for equipment with stringent real-time performance requirements. Additionally, the exemplary infrastructure attempts to minimize the number of connections to the Trusted Authority  203 . Failure to access the TA can impact certain system operations. Specifically, SDS hosts  210  whose security records are not available to the SDS infrastructure will not be authenticated and will therefore assume an operationally disabled state. This will also prevent the TA from authenticating the AP for a new SM. 
     Furthermore, the SDS components can be physically and/or logically integrated with one another, such as where all reside within a common form factor. The present invention is accordingly in no way limited to a particular architecture or configuration. 
     The AP  208  of  FIG. 3 a    is also in data communication with one or more Trusted Authorities (TA)  203  disposed within the trusted authority domain  202 . The trusted authority  203  of the exemplary embodiment comprises the limited number of trusted authentication authorities currently present in the United States; however, it will be recognized that the TA may comprise more or less entities. For example, the NGNA Trusted Authority (TA) is an inter-operator agent for distributing Public Key information currently available in the U.S. Alternatively, the TA functionality can be distributed across two or more coupled or independent entities, may be accessed in a serial or sequenced fashion, may be “virtual”, etc. 
     The TA is responsible for generating, programming, validating and tracking keys associated with the system, including those embedded in the client side DCAS host  210 . The TA goes through variety of steps to authenticate AP  208 ; this can be conducted on an as-needed basis (i.e., each time the AP requests information or authentication of a client from the TA), on a periodic or aperiodic basis, on a rotating key basis, etc. 
     As with the communication channels between the various head-end architecture components  208 ,  304 ,  306 ,  308  the communications between the AP  208  and the TA(s)  203  may be protected using physical, virtual, or other means. Due to the sensitivity of the information carried between the TA(s)  203  and the AP  208 , a high level of security is typically desired on this link (including any interposed links which may provide an opportunity for surreptitious attack or monitoring). 
     Three attributes of this link are particularly significant in the present context. Specifically, the concepts of authentication, data confidentiality, and data integrity are employed as part of the exemplary architecture for protection. These security attributes may be implemented on, e.g., hop-by-hop, end-to-middle and end-to-end basis. These mechanisms are intended to provide important security functions such as identification and verification of the user and/or his or her equipment (authentication), protection of the payload or other data from being read or extracted (confidentiality), and verifying or assuring that the content has not be tampered with or altered (integrity). Authentication is particularly useful against “spoofing” attacks (i.e., third party communications posing to be from a known or trusted source). 
     So-called “anti-replay” protection may also be utilized, using any number of well known mechanisms including e.g., packet sequence integrity. A replay attack can occur for example when a third party obtains a copy of unauthenticated packets, and transmits them to the intended destination at a subsequent time. The receipt of this duplicate packet may disrupt service in some way, or provide other types of surreptitious access. 
     Moreover, the illustrated architecture of  FIG. 3 a    is designed to maintain continuous or near-continuous contact between the TA  203  and the AP  208 , so that AP can verify the client device and issue necessary cryptographic elements in a timely fashion. 
       FIG. 3 b    illustrates a second exemplary embodiment of the SDS architecture according to the invention. In this embodiment, a local or “proxy” trusted authority (i.e., trusted authority proxy  320  is used in conjunction with the remote or distant TA  203  previously described. Use of such a decentralized TAP  320  advantageously permits an increased amount of autonomy for the MSO operations, as well as increased reliability from the standpoint that failure or unavailability of the link between the head-end  150  and the remote TA  203  may not under many circumstances be crippling to continued operation of the MSO network. Reduced latency may also be provided, in that a single TA  203  (or very limited number thereof) is not required to service the potentially great number of requests coming from all networks (MSO or otherwise), which may result in “bottlenecking” based on the TA&#39;s capacity (or that of any interposed networks which the MSOs or other entities use to communicate with the TA  203 ). Specifically, in one variant, the TAP  320  acts as a “secure client” of sorts to the TA  203 , with each MSO network having its own “mini-TA” (i.e., TAP) locally that is enabled to service at least some of the more routine requests generated from the MSO network and its clients. While it is contemplated that the TAP  320  would be maintained physically secure (as well as employing data and network security features including authentication, data integrity, confidentiality, etc. as previously described), this is not a requirement in all cases, since other types of protection mechanisms can be used consistent with the intent of providing a substantially distributed TA architecture that reduces bottlenecking and latency. 
     It will be appreciated that multiple MSO head-ends  150  of the same MSO (or even of different entities) can utilize a common local TAP, or conversely multiple TAPs can be allocated to or disposed at a single MSO network to provide, inter alia, failover capability and redundancy to as to enhance reliability or meet a desired target (e.g., “five 9&#39;s”). Myriad other configurations of TA/TAP/network are possible, as will be recognized by those of ordinary skill. 
     It will further be appreciated that while shown as separate entities, the TAP  320  and the AP  208  can be integrated into one virtual or physical entity if desired, or similarly combined with other entities if desired. For example, another physically secure device or component may already exist in the MSO head-end, and hence integration of the TAP with such device could obviate separate physical security measures for the TAP. 
       FIG. 3 c    illustrates a third exemplary embodiment of the SDS architecture according to the invention. In this embodiment, the AP  208  is disposed at a distributed location (e.g., at a BSA hub site within a BSA network of the type previously described herein with respect to  FIG. 1 c   ). While one AP  208  at one hub site is shown, it will be appreciated that any variations of the number and/or placement of the APs can be used including, without limitation, (i) placing multiple APs  208  at one hub site (e.g., AP “farm”); (ii) placing one AP  208  at a location wherein it can serve multiple hub sites, and so forth. 
     The embodiment of  FIG. 3 c    has the advantage of having a substantially distributed security download (i.e., AP  208 ) architecture that leverages the inherent distributed nature of the BSA switching hubs. Specifically, each hub site or local AP  208  can function substantially independent of the others (or in a distributed but coordinated fashion if desired), thereby avoiding bottlenecking at the AP level. 
     In one embodiment, a carousel server of the type well known in the art is used to stream, or “carousel”, out images (common or personalized) on a continual basis, such as via an in-band downstream channel. In another embodiment, a download server  211  is used that can be dividually contacted by hosts (or SMs) to download specific images (e.g., in a unicast rather than broadcast fashion), similar or equivalent to an FTP/HTTP server. The exemplary download server would connect to the CMTS via the IP network, although other approaches may be used if desired. 
     In the embodiment of  FIG. 3 d   , a local or “proxy” trusted authority (i.e., TAP  320 ) is used in conjunction with the local AP  208 , for a fully decentralized architecture. 
     It will be noted that one salient distinction between the trusted or authorized service domain of the present invention and other forms of content protection (e.g., prior art DTCP or HDCP) relates to the content and software (Client images) remaining under network operator (or third party, via a network proxy) control at all times while in the trusted domain. In the exemplary embodiment, the CPE  106  with security management host  210  comprises the control or access point for the operator within the trusted domain. Specifically, in one variant described in greater detail subsequently herein with respect to  FIG. 5 , a secure microprocessor (SM) is used for this function; the SM is personalized to the specific CPE  106  and network operator with which it is used via software and keys received from the AP  208 . The trusted domain (TD) can therefore be considered to be an extension of the operator&#39;s Conditional Access (CA) system which also implements digital rights management policies under control of the operator. 
     The model for establishing trusted domain (TD) functionality within the CPE  106  according to the exemplary embodiments of the invention can be described as a hierarchy of encryption and key exchange policies and protocols under the control of the operator&#39;s security management system (e.g., that of  FIGS. 3 a -3 d   ). In the exemplary embodiment, the security management (e.g., DCAS) host  210  is responsible for local encryption/decryption of the content, while the SM is responsible for securing and managing the keys used in content encryption/decryption. The architecture is configured so that access to content within the client side of the trusted domain (TD) requires use of the “personalized” SM. The trusted domain is advantageously distinct from any protection used in the transmission of content from the head-end  150  to the premises where the CPE  106  or other target platform is located. 
     Referring now to  FIGS. 3 e -3 n   , one exemplary configuration of the secure download system (SDS) and associated infrastructure of the present invention is described in detail. It will be appreciated that while described in the context of an MSO-based multi-region cable television and media delivery network, the invention is in no way limited to such applications, the following description being merely exemplary. 
       FIG. 3 e    is a functional block diagram of one exemplary embodiment of the network operator infrastructure of the SDS architecture of  FIG. 3 a   , showing its relationship to other network system components. These other components comprise, inter alia, the MSO&#39;s billing system  311 , DOCSIS provisioning system  313 , media security manager  328 , and the media services manager  341 . 
       FIG. 3 f    is a functional block diagram of one exemplary embodiment of the network operator infrastructure of the SDS architecture of  FIG. 3 e   , showing additional details thereof including the relationship of the PS  306  and the MSS  328 , and the local key server (LKS)  330 . The exemplary SDS infrastructure further comprises a dedicated SD provisioning system  332 . Each of these components are described in greater detail subsequently herein. 
       FIG. 3 g    is a graphical representation of one exemplary embodiment of the media security services portion of the network operator infrastructure of the SDS architecture of the invention, illustrating the various functional entities including the CA systems  304 , DRM system  345 , and TD system  347 . Note that each has a PC component  306  associated therewith for providing personalized (e.g., SM-specific) versions of their respective client images. 
       FIG. 3 h    is a functional block diagram of one exemplary embodiment of cable television network head-end including the SDS architecture of the present invention, showing the interrelationships between various components and functions disposed primarily within the cable network head-end, although it will be appreciated that these components and functions may be distributed at other locations. 
       FIG. 3 i    is a functional block diagram of one exemplary embodiment of cable television network having multiple network regions, including a distributed SDS, according to the invention. As shown in  FIG. 3 i   , the SDS infrastructure is distributed across multiple MSO regions (A, B, C), with APs  208  serving one or more of these regions (and their associated CA, DRM, and TD systems and Personalization servers  306 ). As noted, multiple PS devices can be serviced by one AP  208 . 
       FIG. 3 j    is a functional block diagram of one exemplary embodiment of the SDS architecture of the invention, showing secure and non-secure components and interfaces. 
       FIG. 3 k    is a logical block diagram of one exemplary embodiment of the authentication proxy (AP) of the SDS architecture of the invention, showing various messaging and interfaces to and from the AP. 
       FIG. 3 l    is a logical block diagram of one exemplary embodiment of the personalization server (PS) of the SDS architecture of the invention, showing various messaging and interfaces to and from the PS. 
       FIG. 3 m    is a logical block diagram of one exemplary embodiment of the local key server (LKS) of the SDS architecture of the invention, showing various messaging and interfaces to and from the LKS. 
       FIG. 3 n    is a logical block diagram of one exemplary embodiment of the SDS provisioning system (SPS), showing various messaging and interfaces to and from the SPS. 
     The primary components and functions of the foregoing exemplary SDS architecture are now described in greater detail. 
     MPS Device Provisioning 
     In an exemplary leased equipment model, the device provisioning function of the MPS  308  (see  FIG. 3 f   ) receives commands from the network operator&#39;s billing system  311  indicating a CPE  106  is being added or removed from the system. The addition of a CPE  106  may be instigated by subscriber initiated contact with a network operator customer service rep. (CSR) in order to provide CPE identification and location information, although it will be appreciated that other approaches may be used with equal success. For example, in one alternative, two-way communications with the CPE could be used to automatically discover new devices joining the network (i.e. certain retail scenarios). The MPS device provisioning function  333  ( FIG. 3 f   ), part of the MPS  308 , receives this information and can instigate the download of SM Client images. The download channel (e.g., DOCSIS CM) provisioning flow is triggered by the MPS device provisioning system function to load the appropriate firmware or software consisting of cable modem (CM) and CPE images. 
     MPS Service Provisioning 
     The MPS service provisioning function  335  ( FIG. 3 f   ) is responsible for resolving and distributing service entitlement requests across all the CA systems  304  in the network. MPS service provisioning  335  receives service provisioning requests from the billing system  311 , resolves the service request with the capabilities of the CPE  106  as required, and then routes the service provisioning flow to the appropriate CA system. As will be recognized by those of ordinary skill, the SDS capabilities of the CPE  106  may accordingly influence the service provisioning function&#39;s operation and flow. The head-end controller for the CA system  304  contacts the CA Client(s) as required by the CA system configuration. 
     MPS Entitlement Configuration 
     The Entitlement Configuration (EC) function  337  ( FIG. 3 f   ) is responsible for coordinating entitlement IDs across the multiple CA systems within the network. This permits the Media Service Management (MSM) functions  339  (see  FIG. 3 h   ) to be independent of the CA system(s)  304 . The EC  337  communicates entitlement identifiers (EIDs) to the MSM  330  for use in service catalog creation. The SDS capabilities of the CPE  106  may also influence the entitlement configuration. 
     The MPS entitlement configuration function  337  abstracts the service request from the billing system  311  into a set of common entitlement configuration messages for communicating with other subsystems in the media (e.g., video) infrastructure. 
     Media Security Services 
     The Media Security Services (MSS)  328  apply and manage content and service access control. It is assumed in the illustrated embodiment that the distributed system consists of multiple CA systems  304  running both duplicate and distinct CA system software, although other configurations are possible. For the purpose of securing broadcast content, the DRM and TD systems are considered possible CA systems within the MSS  328 . 
     Each CA system technology within the MSS  328  receives a common configuration of EIDs from the EC  337 . Each CPE&#39;s secure microprocessor (SM)  514  (see  FIG. 5 ) is associated with a CA system by the AP  208  (via the PS  306 ). The CA system  304  receives service entitlement requests for associated network hosts  210 . In turn, the CA system generates and delivers the entitlements. Additionally, the CA system  304  is informed for which services it needs to generate encryption. It interacts with a shared bulk encryptor (e.g. SimulCrypt or partial encryption) via the exemplary entitlement control message generation function (ECMG)  349  to SimulCrypt Synchronizer (SCS) interface providing the ECMs needed for its assigned hosts  210  in order to decrypt the service. 
     Each CA system  304  within the MSS  328  interacts with the AP  208  (via the PS  306 ) to provide personalized SM Client images for download into the SDS host  210 . The CA system  304  securely generates a common SM Client image which is downloaded by all SMs  514  sharing a common hardware and software configuration. 
     In addition to the CA system&#39;s interface to the SDS infrastructure through the Personalization Server  306 , the CA systems  304  of the illustrated embodiment implement three other interfaces to the operator&#39;s support system (OSS), namely: (i) a CA system provisioning interface; (ii) an entitlement configuration interface; and (iii) SimulCrypt Synchronizer to ECM generator interface. 
     The CA system provisioning interface is used in certain deployment scenarios to request device and service provisioning by the CA system  304 . The protocols implemented to support this interface are traditionally a proprietary technology unique to each CA system vendor (e.g. BOSS, WireLink), although other approaches such as standardized protocol may be used. 
     The entitlement configuration interface allows the Media Provisioning System  308  to provide the CA system  304  with the EIDs associated with each service. 
     The SimulCrypt Synchronizer to ECM generator interface is used by the CA system  304  to receive keys and deliver ECMs to the bulk encryptor. It will be appreciated that will a SimulCrypt-based system is shown and described, the invention is in no way limited to this (or for that matter similar) approaches. 
     Media Services Management (MSM) 
     The Media Service Manager (MSM)  339  is responsible for configuration and management of broadcast media (e.g., video) services, third-party applications (both native and OCAP), and eTV services. Responsibilities of the exemplary MSM  339  include service catalog and service information, OCAP Application Certificate Management, Emergency Alert, XAIT/AIT configuration, SDB Service and broadcast carousel management. The MSM  339  operates independently from the type of CA systems  304  in the network, allowing seamless service delivery within a heterogeneous CA system environment. To operate independent of the CA system(s)  304 , the MSM  339  receives EID information from the ECM  337  (within the MPS  308 ). 
     In order to support the network independence of SDS hosts  210 , the MSM  339  of the illustrated embodiment delivers network-specific software required for host operation and is termed the Conditional Access Network Handler  421  ( FIG. 4 b   , application layer). 
     The Broadcast Network Manager (BNM)  341  ( FIG. 3 h   ) is a logical component paired with the CANH/network handler  421  running on the host CPE. It originates the network specific interfaces terminated by the CANH/network handler. For example, the BNM  341  is the source of DSM-CC pass-thru messages in networks where this is the message delivery mechanism of choice. 
     Billing System 
     The billing system  311  of the exemplary embodiment is a database management system comprising a database and a set of operator-facing applications, such as “Billing” and “Customer Care”. In general, the billing system  311  is used by the network operator to: (i) enter service add, change or delete orders; (ii) generate service packages; (iii) reconcile accounts and inquire about billing issues; (iv) generate billing statements; and (v) process payments. The exemplary billing system  311  also contains APIs to enable functional extensibility and for system customization. 
     In general terms, the billing system  311  communicates device and service provisioning information (ID of the transport processor  516 ) to the MPS  308  indicating the services a subscriber has subscribed to or is entitled to access. The billing system  311  also communicates to the MPS which devices are associated with a subscriber account. 
     The SDS infrastructure of the present invention is also optionally configured to support the mediation and distribution of purchase record information between MSOs. Purchase information is recovered from an SM  514  by an AP  208  using a prescribed protocol. The AP  208  forwards this information to the MSO&#39;s purchase arbitrator (PA) function, not shown, in order to support purchase record resolution. 
     Provisioning 
     Equipment provisioning within the network requires interaction with the CA system  304  (via the MPS). Service provisioning is dependent on a form of MSO-defined Device ID and Service ID determined during service provisioning. 
     In a leased equipment scenario, if an SM Client image  422 ,  434 ,  438  ( FIG. 4 b   ) download is initiated by a service provisioning order through a Customer Service Representative (CSR), the billing system  311  sends a unique device identifier (e.g. the Transport Processor ID or TPID) and SDS host topology information to the MPS  308 . In turn, the MPS signals the SDS infrastructure to initiate the approved SM Client image download to the SDS host  210 , and returns a confirmation to the billing system  311  that identifies the PS  306  to which the device has been assigned. The unique host identifier (e.g. TPID) is used by the billing system  311  to provision services using the PS  306  with specified MSO topology information. 
     In a retail equipment scenario, if an SM Client image download is initiated by a host  210  being placed on the network, the billing system  311  may receive the unique device identifier (e.g. TPID) and SM topology information from the MPS  308  as reported by the SDS infrastructure. The AP  208  provides this information, including first network connection time stamp, host identification, and other host client configuration information. The MSS  328  provides the services authorized to run on that SDS Host  310 . The MPS  308  may need to reconcile the TP Identifier with the CPE/CM IP address and other customer account information. 
     A central purpose of the SDS infrastructure is to securely deliver approved SM Client images  422 ,  434 ,  438  to the SM  514  of CPE  106 . This delivery is completed in two parts for each SM  514 ; one for the “common” part of the image and one for the personalized part of the image. The approved common image part is made available to all SMs of like configuration using a specific CA system  304 . The personalized part of the SM Client image is targeted toward a single SM  514 , and is therefore delivered using a unicast mechanism of the type well known in the network arts. 
     An assortment of SM Client images and combinations may be downloaded and managed by the SDS infrastructure simultaneously. These downloads are orchestrated by the AP  208  which enforces SDS provisioning system policy to control which approved SM Client image is delivered to which SM  514 . The region over which any bulk upgrade of SM Client images is performed is also controlled and rate-limited in order to limit the amount of network traffic and host resource load added during SM Client image downloads. Download activity is logged by the AP  208  allowing for tracking and reporting of SDS operations. 
     In order to securely distribute the SM Client images, the SDS infrastructure first obtains images and/or image locations from the CA System vendor or other appropriate source via the PS  306 . The common image is securely delivered to the download site, and specific SM information must be provided to the PS  306  for the creation of the personalized SM Client image(s). In the illustrated embodiment, both common and personalized SM Client images are generated and symmetric key encryption or some other mechanism encrypted by the PS  306 . Each common SM Client image is encrypted using a unique AES Key which is securely delivered to each SM  514  that installs the Client image. 
     It is assumed that all SDS hosts  210  are of a configuration capable of completing an SM Client image download when it is attached to the network. 
     Enforcement of Image Configuration Policy 
     The SDS infrastructure of the present invention advantageously provides a framework for the definition and enforcement of network operator-defined policy reflecting which CA, TD, or DRM client configuration(s) are running within all SDS hosts  210  on the network in order to assure that only approved SDS Clients are operating within the network. 
     Before an SM  514  downloads an approved SM Client image  422 ,  434 ,  438 , the SM must be properly authenticated to the network. Upon initial authentication (when an SM is new to a network), keys are retrieved through direct or indirect contact with the AP or TA  203 . Following this initial transaction, subsequent authentications are performed through interaction between the SM  514  and AP  208 . The MSO&#39;s SDS Infrastructure interacts with the TA in order to obtain keying and SM configuration data. 
     The exemplary SDS infrastructure announces a list of MSO-approved SM Client images for each class or model of SM  514  or SDS host  210  (e.g., CPE  106 ) on the network. This is used to indicate to devices migrating into the system the set of approved SM Client images (software) that they need to install. The SDS infrastructure also signals the network information of the AP  208  to which the SM  514  should associate. This information can be delivered in a number of ways including for example via a CM gateway (e.g., so-called “DSG tunnel” as shown in  FIG. 4 c   ), DOCSIS multicast, or IP multicast. Several different announcement messages (see discussion of SDS Messaging and Protocol provided subsequently herein) can be generated for different logical or device topologies of the network from the same AP  208 . 
     Through a message created by the TA  203  and forwarded through the AP  208 , the SM  514  is given keys that allow it to establish security relationships with the AP it is communicating with. At the successful termination of this process, the client  432  confirms the SM  514  to TP  516  pairing, as well as its public encryption and signing keys (SMEK, and SMSK, respectively). 
     SDS Infrastructure Components 
     Referring now to  FIGS. 3 k -3 n   , individual components of the SDS infrastructure previously described are discussed in greater detail. In the exemplary embodiments, distributed components are deployed throughout the SDS Infrastructure in order to provide targeted SM Client image downloads to subsets of the overall host population. As previously noted, the host population can be subdivided in several ways including, without limitation, by CPE  106  device type, device services, target CA system  304 , operator policy, geography, etc. (or some combination of the above). In the illustrated embodiment, an attempt has been made to divide operations between those requiring secure elements and those that do not, although this is not a requirement for practicing the invention. 
     Authentication Proxy (AP) 
     The Authentication Proxy  208  (see  FIG. 3 k   ) is a primary component of the SDS infrastructure, and a unit of scalability therein. See, e.g.,  FIG. 3 i   , wherein several APs  208  are scaled across a number of different MSO regions and CA systems  304 . 
     The AP is embodied as a physically and logically secure component (e.g., computerized device such as a rack-mounted UNIX or Linux server having digital processor, mass storage, RAM, optional user interface and display, etc.) that communicates directly with SMs  514 , TAs  203 , the Personalization Server  306 , and the SDS Provisioning System  332 . It will be appreciated that the AP may be a largely stand-alone device/form factor, or alternatively may be integrated with extant or SDS components. For example, in one variant, the AP  208  comprises a server blade received within an existing cable system host device present at the head-end  150  or BSA hub site. The AP may also be equipped with dedicated or specialized hardware and/or software (e.g., a security processor) for accomplishing specific tasks or functions within the disclosed security architecture such as, e.g., cryptographic algorithm processing, random number generation, and the like. Many different configurations recognized by those of ordinary skill in the computer arts may be used consistent with the present invention. 
     The exemplary embodiment of the AP  208  provides a variety of different functions within the SDS infrastructure. Specifically, the AP  208 : (i) receives approved SM Client Identifier policy and other information from the SDS Provisioning System  332  (or other MSO defined interface) in order to direct SMs to the required software Image configuration; (ii) securely announces approved SM Client image configurations and download information; the AP is capable of generating multiple secure announcements based on network topology, image policy, and SDS host configuration; (iii) authenticates with the TA  203  and the PS  306 , and in conjunction with the TA, authenticates SMs  514  and TP  516  pairings; (iv) mediates SM cryptographic element request transactions between an SM and the TA  203 , as well as updates the LKS  330  with SM element (e.g. keys, such as SMEK, SMSK) through contact with the TA or LKS; (v) securely interfaces with one or more PS  306  where the PS may service all SM Client types (CA, DRM, TD) or a single SM Client type; (vi) securely requests symmetric key encrypted common SM Client images and co-ordinates SM download of the common image, and also directs SM Clients to correct common image location, as well as controlling the scheduling of download; (vii) securely forwards the SM SMEK to the PS  306  in order for the PS to encrypt the SM personalized image; (viii) securely forwards a symmetric key encrypted personalized SM Client image from the PS  306 , and forwards it to the relevant SM  514 ; (ix) signals completion of SM Client image downloads to the relevant PS  306 ; (x) implements server-side protocols (e.g., PMP and NPM protocols); (xi) generates local keys for communication using specialized hardware (e.g., specially configured and physically secure encryption/decryption processing boards or modules); (xii) persists and reports the configuration and status of SM Clients (e.g., TD, CA, and DRM Clients  422 ,  434 ,  438  running on the SM  514 ); (xiii) receives, persists, and forwards purchase-related information (e.g., purchase report messages) from the SM  514 ; and (xiv) requests and forwards SM Log messages from the SM-stored information logs on behalf of the MSO&#39;s Network Management System (NMS)  343  ( FIG. 3 h   ) and other operations support system functions. 
     In the exemplary embodiment, the AP securely generates random numbers necessary for message identification and other informationas required by the SDS Protocol. Specifically, The AP securely generates random numbers for producing unique session keys according to FIPS140-2, although this is but one possible configuration. 
     The AP can obtain (and store in secure memory associated therewith) an RSA encryption key pair, and an RSA Signing key pair, each signed by the Trusted Authority  203 . The illustrated AP supports multi-bit asymmetric encryption key pairs as well as the RSA algorithm for signing and verification (as well as for encryption and decryption), although it will be appreciated that other encryption schemes and requirements may be substituted with equal success. 
     The AP also supports symmetric key encryption for encrypting attachments to SDS messages, as well as secure hashing algorithms for hashing in applicable SDS messages, using algorithms well known to those of ordinary skill in the cryptographic arts. 
     The AP also may be optionally configured for various tiers of users (using any number of well-known multi-tier, multi-user access control software packages), so only the authorized administrators can update the configuration of the AP server itself. 
     The AP communicates with the broadcast carousel and download servers (TFTP, HTTP) to load common SM Client images. 
     In the illustrated embodiment, the AP  208  is also configured via its software programming to delete a SM/TP pair from the regional network when a network move is known to have occurred. The AP delivers SM public encryption keys to the PS. AES keys are used by the PS  306  to encrypt unicast SM Client images and can be encrypted in the PS using the SM public key. 
     The AP also provides a mechanism to control, suspend, and resume SM Client image downloads under both normal and emergency circumstances. The AP is also configured to automatically turn off SM Client Image downloads in the case that many SMs are reporting failure to upgrade or there is no response from the group of SMs after a configurable time period. 
     In terms of data persistence, the exemplary AP supports communication of DCAS information by groups of Host IP address, Host HW and SW version, Model Number, SM Client Image(s) version, DSG tunnel address and SM identification information (SMID) as instructed by MSO configuration and Policy. 
     The AP supports a minimum number (e.g., one hundred (100)) common SM Client images as well as inventory and tracking of the various CA/DRM/TD Client images it has been made aware of through interaction with the PS, SPS, and SMs. The AP also provides visibility into SM Client image-related information such as SM Client status, SM Client image configuration, and SM Client image download status. 
     In one configuration, the AP allows for complete failover redundancy with a high-availability configuration in the event of a component failure using a 1:1 redundancy configuration. In this configuration, a primary AP failing would be immediately replaced by the redundant AP to support connectivity or authentication of new devices on the network. The exemplary AP is also configured for “five-nines” availability as previously discussed. 
     In the illustrated embodiment, the AP  208  is configured to authenticate at minimum rate of 50 SM Clients per second. This rate assumes that updated keys exist in both the SM and AP and no communication with the TA is required as part of the authentication process. An AP MUST support a minimum of 1 million SM Clients. 
     The AP supports both scheduled and forced immediate downloads as directed by MSO download policy, as well as triggering forced downloads to individual SMs and to groups of SMs as instructed by the SPS policies. The exemplary AP also supports transitioning between old, new and roll back of SM Client images. 
     Personalization Server (PS) 
     The SDS Personalization Server (PS)  306  (see  FIG. 3 l   ) couples one or many CA System(s)  304  (as well as DRM and/or TD subsystems) with the SDS infrastructure. The exemplary embodiment of the PS  306  comprises a physically and logically secure computerized system (e.g., server, blade, etc.), and acts as the source of all personalized SM Client images for distribution, download, and management by the SDS infrastructure. 
     The PS  306  provides SM Client images to support CA, DRM, and/or TD functionality. While shown in the exemplary embodiments (e.g.,  FIG. 3 h   ) as separate entities, the PS functions for each of these different aspects (CA, DRM, and TD) can be integrated into one logical process and even one physical form factor if desired. 
     In the exemplary embodiment, one PS  306  exists for one or many CA, TD, or DRM system instances, and provides the following functions: (i) authenticates with its associated AP(s)  208 ; (ii) accepts requests forwarded by the AP for SM Client images; (iii) determines which SM Client image components are to be updated, and encodes both the common and personalized images accordingly; (iv) generates the image cryptographic elements (e.g., AES image keys) for the personalized and common SM Client image downloads; (v) generates personalized SM Client image components based on, inter alia, the SM&#39;s chip identifier; (vi) identifies the common image components and location of the SM Client image based on the SM&#39;s class identifier; (vii) returns a signed and encrypted pair of cryptographic elements (e.g., AES keys) to the AP  208  for unicast delivery to a specific SM  514  associated with an SDS host  210 , thereby allowing the SM  514  to decrypt both the common SM Client image and the personalized SM Client image; (viii) interfaces to one or more CA systems  304 ; and (ix) receives status updates of SM Client image download status and failures from the AP  208 . 
     The PS  306  maintain records of the number of download transactions and which SMs received downloads after receiving confirmation from AP (based on the AP receiving a DownloadComplete or similar communication from the SM  514 ). The PS also provides programmable alarming to indicate passing a threshold in the number of available personalized SM Client images, thereby potentially indicating faulty or surreptitious behavior. 
     The PS of the exemplary embodiment is configured to deliver personalized SM Client images at a minimum sustained rate of 100 SM images per second. This rate assumes that updated keys exist in the PS, SM and AP and no communication with the TA is required as part of the personalized image delivery. The PS generates low-latency responses to all AP requests (e.g., within 1 second of receiving). 
     The PS generates and securely provides the common SM Client image to the AP  208  encrypted with a common symmetric key generated by the CA system  304  based on, e.g., the SM Class Identifier provided by the AP. The PS also generate the personalized SM Client image symmetric key (which is itself encrypted with the target&#39;s SMEK). The PS further provides the common SM Client image protected with asymmetric key (also encrypted using the SMEK). 
     Local Key Server (LKS) 
     The Local Key Server  330  ( FIG. 3 m   ) of the illustrated embodiment comprises an optional, persistent, physically and logically secure store of MSO security information. The content of the LKS  330  reflects the MSO&#39;s keying information for the entire trusted key store across all client and network devices, thereby providing benefits in terms of reduced communication overhead, centralized storage, redundancy, and reduced latency for accesses. Specifically, in one aspect, such an approach reduces the number of communications between the AP and the TA. 
     The Local Key Server  330  acts as a logical entity independent of any other component within the SDS infrastructure, and can be implemented in a number of different physical and logical configurations in order to best suit the architectural requirements of the MSO. 
     The exemplary LKS  330  of  FIG. 3 m    provides the following functions: (i) provides a local cache of MSO keying information useful for disaster recovery and provisioning workflow for APs  208  and the SDS provisioning system  332  (see  FIG. 3 j   ); (ii) contains all SM keying information (e.g., SMEK, SMSK) for the MSO network; and (iii) contacts the TA  203  using a secure (e.g., transport layer security or TLS) interface for the retrieval of secure records. 
     The contents of the LKS  330  can either be updated through contact directly with the TA  203 , or via an AP  208  or other such entity that has received updated keys directly from interaction with the TA  203 . 
     SDS Provisioning System (SPS) 
     The SDS Provisioning System (SPS)  332  ( FIG. 3 n   ) is the central manager and repository for SM Client image configuration and MSO approved client policy. Recognizing that each MSO takes different architectural approaches to their provisioning system environment, the exemplary SPS  332  is designed with a high degree of agnosticism, thereby accommodating many different provisioning system implementations. 
     Hence, the SPS  332  can be characterized in terms of its primary high-level functional requirements, including: (i) serving as a Policy Decision Point (PDP) for MSO SDS policy including approved client identifiers, SM Client image download configuration, download directives and schedule, priority, and download mechanism; (ii) distributing SDS policy to APs  208 ; (iii) providing optional interface with the LKS  330  in order to retrieve keying information; (iv) responding to AP notifications for unrecognized SDS hosts  210  or requests for SM Client image configuration and download policy; and (v) determining the topological relationship between the SM  514 , AP  208 , PS  306 , and CA, TD and DRM systems (i.e., the AP understands the location of the SM (or host) in the network, and can accordingly identify the appropriate PS to use, along with the necessary CA, TD and DRM systems). 
     The SPS allows the MSO to assign it one or more APs  208 , and to assign Personalization Servers  306  to the APs. 
     The SPS supports configuration of SDS policies based on communication of CA/TD/DRM information by groups; e.g., by Host IP address, Host HW and SW version, Model Number, Firmware version, DSG tunnel address, Host associated Tier of Service and SM identifying information (i.e. policy management based on host profile). 
     The exemplary SPS further supports configuration of the time and frequency of security record requests. 
     Interfaces 
     In the exemplary embodiments, the SDS infrastructure components interact through a collection of network software interfaces (NSIs). A total of seven (7) SDS infrastructure NSIs are used within this exemplary architecture, although it will be appreciated that more or less interfaces, and even different types of interfaces, may be used consistent with the invention. 
     Of these seven interfaces, only a subset of four (4) are specified, while three (3) are implementation-specific (e.g., MSO defined) and therefore advantageously can reflect the potentially different system and architectural requirements unique to each MSO. These seven interfaces include: (i) Secure Records Exchange Interface (DCAS-SRXI); (ii) Image Exchange Interface (DCAS-IXI); (iii) Purchase Report Interface (DCAS-PRI); (iv) Secure Key Request Interface (DCAS-SKRI); (v) Operational Support System Interface (OSSI); (vi) Provisioning Interface; and (vii) Local Records Exchange Interface. These interfaces are now discussed in greater detail. 
     (i) Secure Records Exchange Interface (SDS-SRXI)—In addition to the Key Request Interface, the TA  203  also provides keying information via the SRXI to the Local Key Server  330 . The LKS periodically requests updated keying information for the local caching of security records, as previously described. The content of the messages from the TA  203  to the LKS  330  over the SRXI includes updates of the following: (a) SM encryption and signing keys (SMEK, SMSK) for all SMs within the MSO SDS infrastructure; (b) SM  514  to TP  516  pairing information including TP Pairing Keys (TPPK) for all SDS hosts  210  within the MSO SDS infrastructure; (c) AP encryption and signing keys for each AP  208  within the MSO SDS infrastructure; and (d) PS encryption and signing keys for all PSs  306  with the MSO SDS infrastructure. 
     The SRXI provides mutual authentication and privacy between the TA and the LKS  330 . The SRXI allows the LKS to obtain security records in a standard format from TA  203 , and allows the LKS to request and obtain security record updates at any time. The SRXI only delivers security records for devices authenticated to the MSO, yet allows the LKS to obtain the security records for all SDS hosts  210  authenticated to the MSO or delivered retail. This can be done for individual and groups of SDS devices. 
     The SRXI also prevents unauthorized monitoring of the exchange. It implements a Web Service (WS) interface between the AP and LKS that enables the LKS to dynamically request updates of the TA security records. 
     The SRXI of the illustrated embodiment is based on the well-known SOAp/eXTensible Markup Language (SOAP/XML) version 1.2, although other languages may be used with equal success, the SRXI being effectively language-agnostic. The SRXI implements Secure HTTP (HTTPS) as the message transport, although other secure (or even non-secure) transport protocols may be used consistent with the invention. 
     (ii) Image Exchange Interface (SDS-IXI)—Each PS  306  and AP  208  communicate via the Image Exchange Interface (IXI) for interaction supported by the PS  306 . The IXI interface provides a medium for at least three functions; (1) PS and AP mutual authentication, (2) common SM Client image download information exchange, and 3) personalized SM Client image information exchange. 
     The authentication function occurs first in order to establish trust between the PS  306  and the AP  208 . The PS is, in the illustrated embodiment, required to periodically request AP key information directly from the Trusted Authority  203  in order to update its local trusted key store in order to verify AP signatures. The message path for this key request is through the AP, which forwards the request to the TA. 
     Likewise, the AP  208  is required to periodically request PS key information from the TA in order to update its local key store in order to verify PS signatures. 
     The SM Client common image exchange function requests new common image download information that will be shared by the SDS hosts  210  assigned to a specific PS  306 . 
     The SM Client image exchange occurs for each SM  514  assigned to the PS. According to one exemplary protocol ( FIG. 3 o   ), the AP  208  first provides device credentials along with the SM public key to the PS (step  380 ). In turn, the PS returns a device-specific personalized SM Client image, along with common SM image download directives and decryption information (step  382 ). The SM Client image download is encrypted for the specific SM target (e.g., CPE  106 ) per step  384 , and forwarded by the AP as a message attachment (step  386 ); see discussion of message formats and protocols provided subsequently herein. 
     Finally, the AP signals the PS per step  388 ) to indicate the success or failure of delivery of the SM Client images to the SM  514  of the target host. 
     The exemplary IXI implements the Personalization Message Protocol (PMP, a protocol specifically developed for image exchange, although other approaches may be used). The IXI permits the AP to use the SM Class Identifier and SM Client Identifier to request the common SM Client image. The IXI allows the PS to create a personalized SM Client image and deliver the common image encryption key in a message that is specifically encrypted for the target SM. The IXI further allows the AP to provide the SM Identifier and public key to the relevant CA system  304  (via the PS) in exchange for the secured common SM Client image encryption key. The IXI also permits the AP to report SM Client image download status to the PS. 
     The AP communicates with the Personalization Server  306  regarding SM Client image information and which devices are assigned to which SM Client image version using the IXI. The AP securely forwards the personalized SM Client image obtained from the PS using the IXI. The AP receives all personalized Client images over the IXI using the PMP, and then forwards using an appropriate message. 
     (iii) Purchase Report Interface (SDS-PRI)—The SM Purchase Report Message (PRM) is defined so as to enable the transfer of SDS host-stored purchase report information from the SM  514  of the host  210  to the AP  208 . The purchase report information forwarded by the SM is in the illustrated embodiments returned to the CA System  304  from which it originated. The AP persists, and forwards all reports received from all SMs to a “purchase arbitrator” via the PRI. The purchase information forwarded by the AP on behalf of each SM includes, e.g.: (a) the SM Purchase Report attachment; (b) the SM secure microprocessor&#39;s encryption key (SMEK); (c) the APID (AP Identifier) when a valid purchase was made; (d) the SM Client Identifier; and (e) the TPID (TP Identifier). 
     (iv) Secure Key Request Interface (SDS-SKRI)—The primary interface for the distribution of keying information from the TA  203  is the SKRI. The SKRI provides a transactional interface for the updating of key information and a path to retrieve security records based on both SM and PS key requests. 
     The SKRI interface is used in the exemplary embodiments to carry requests for keying information between the AP  208  and the TA  203 , including: (a) SM/AP—an SM  514  will request AP key information from the TA (the SM request tunneled to the TA  203  through the AP  208 ) if it does not recognize the AP (APED) to which it is assigned, or it detects a signature verification failure; (b) AP/SM—an AP will request updated SM key information from the TA  203  for a single SM Client when the SM is unrecognized (e.g., new) or the keying information for the SM is not otherwise available to the AP. An AP may request updated SM key information in conjunction with a SM request for TA keys by ‘piggybacking’ the forwarded SM key request for TA keys with its own request for the SM&#39;s keys; (c) PS/AP—a PS  306  will request updated AP keying or status information from the TA for an AP to which it is interfaced for the purposes of signature verification; and (d) AP/PS—an AP will request updated PS keying information from the TA for the purposes of PS signature verification. 
     In the illustrated embodiments, the message path of all TA key requests is through the AP, which in turn forwards messages to the TA via the SDS-SKRI. 
     The exemplary SKRI provides mutual authentication and privacy between the TA and the AP, and allows the AP to obtain security records in a standard format from TA  203 . The SKRI delivers security records for client and network devices associated with the MSO and those SMs known to be retail only. A Web Service (WS) interface is also provided between the AP  208  and LKS  330  that enables the LKS to dynamically request updates of the TA security records. 
     The SKRI of the illustrated embodiment is based on the well-known SOAp/eXTensible Markup Language (SOAP/XML) version 1.2, although other languages may be used with equal success, the SKRI being effectively language-agnostic. The SKRI implements Secure HTTP (HTTPS) as the message transport, although other secure (or even non-secure) transport protocols may be used consistent with the invention. 
     The AP forwards SM KeyRequest messages to the TA and TA KeyResponse messages to the SM using the Key Request Interface. 
     (v) Operational Support System Interface (OSSI)—The Operational Support System Interface is provided for the exchange of network management information between the SDS infrastructure and the OSS/NMS of the MSO. In one embodiment, the SDS-OSSI implements standard network management protocols for the collection and distribution of operationally significant SDS infrastructure information (such as SM Local Logs, SM Status information, and AP alerts); use of such standard protocols advantageously avoids proprietary or new protocols, thereby simplifying SDS infrastructure implementation in existing networks. 
     (vi) Provisioning Interface (PI)—Recognizing that operators implement varying OSS infrastructures and “back-office” configurations, the provisioning system interface (PI) is included to permit communication between various provisioning system components and the AP  208 . 
     When an SM joins the network, the MSO SDS Provisioning System (SPS)  332  provides the AP  208  with the approved SM Client identifiers and download directives corresponding to the SM Capabilities and Policy. The PI may be used to carry SDS host network location and SDS host identification information between the AP and SPS. In addition, the PI may carry SDS download policy and scheduling information to the AP from the SPS  332 . 
     (vii) Local Records Exchange Interface (LRXI)—Components of the SDS infrastructure such as the AP  208  and SPS  332  may request keying information stored in the Local Key Server  330  using the LRXI. In addition, an AP may update SM keying information in the LKS  330  based on current SM keys that the AP has received directly from the TA  203 . The details of specific LRXI implementations and configurations are intentionally flexible and left to the MSO. 
     The content of messages exchanged over the LRXI includes: (a) keys for all SDS hosts  210  associated with a specific AP  208 ; (b) the TP pairing key for all SDS hosts associated with a specific AP; and (c) keys associated with a specific AP. 
     Appendix I hereto describes these exemplary interfaces in greater detail. 
       FIG. 4  illustrates a generalized high-level software architecture  400  for use in providing the security download functions of the present invention. This architecture is designed to satisfy several functions, including inter alia: (i) creating a secure system for downloading CPE (i.e., SM Client) software in the field; (ii) implementing a secure system for cryptographic element (e.g., key) management, distribution and validation; (iii) providing adequate user functionality in the absence of 2-way communication while also meeting security objectives; (iv) support for simultaneous video decryption streams and key management; and (v) implementation of a common architecture for both lease and retail CPE models. 
     Specifically, as shown in  FIG. 4 , the architecture  400  comprises a trusted authority (TA) component  402  that is in logical communication (over network or other physical links of the type previously described herein with respect to  FIG. 2 ) with an authentication proxy (AP) component  404 . The AP component  404  is in communication with an MPS component  406 , as well as a conditional access component  408 . The AP component  404  is also in logical communication with the host component  210  previously discussed with respect to  FIG. 2 . It will be appreciated that while the AP, MPS, and CA components  404 ,  406 ,  408  are shown disposed at the head-end  150  of the network, other architectures and placements may also be readily employed, such as where one or more of these components are disposed at a BSA hub site within a broadcast switched network (see, e.g.,  FIG. 3 d   ). 
       FIG. 4 a    illustrates an exemplary software and firmware architecture used within the CPE  106  of  FIG. 4 . The trusted domain (TD) and download functionality of the present invention is, in one embodiment, distributed across several software components and layers (including an application layer  416 , middleware layer  418 , platform code layer  428 , and SM layer  430 ) present in the target platform (e.g., CPE  106 ). Specifically, as shown in  FIG. 4 a   , these software and firmware components comprise: (i) a TD SM Client  422  which is either pre-positioned or downloaded to run in the secure microprocessor (SM); (ii) a TD Host module  424  resident on the target platform; and (iii) an TD Handler  426  module which is configured and downloaded by the network operator. 
     The TD Host  424  is responsible in the exemplary embodiment for providing TD-standardized encryption and decryption of the content streams, as well as storage of security packages associated with content. The TD Client  422  is responsible for processing management data and information (e.g., content management information or CMI), generating encryption keys for the content, and controlling access to content stored within the TD (e.g., through processing of security packages). In the illustrated embodiment, the TD Host  424  is responsible for the encryption and decryption of content, while access to the cryptographic key (i.e., “content” key) needed to decrypt the content can only be provided by the TD Client  422  associated with the SM code layer  430 . The TD Handler  426  interfaces with both the TD Client  422  and the TD host  424 , and is responsible for, inter alia, pacting as a proxy for information transferred between the TD client/system and OCAP applications. 
     The security download bootloader module  432  in the exemplary embodiment comprises firmware loaded on the SM during manufacture or upon installation (although in some embodiments where the firmware is not “burned in,” it may also be “flashed” or reprogrammed if desired in certain embodiments, such as via a download from the head-end or hub site). Upon SM boot-up, the bootloader  432  checks the CA client  434  for integrity and correctness according to data received from the authenticated MSO network. The bootloader  432  ultimately hands off control of the SM to the verified CA Client  434 . The bootloader also “wipes” off SM data upon a new SM Client (i.e., CA Client, DRM Client, or TD Client) software load from the network. 
     The CA client  434  comprises conditional access code that is downloaded onto the CPE and that is particularly adapted to the network within which the CPE is operating. This code handles the key management and control for conditional access systems, as described in detail subsequently herein with respect to  FIG. 6   b.    
     The SM driver  436  is part of the host platform (e.g., CPE) code and provides a software interface from the host platform code to the SM code. The SM driver routes messages to and from the SM, and maintains information on the state of the SM. 
     The DRM client  438  comprises DRM code that is downloaded onto the CPE and is, in one embodiment, responsible for working with other “output domain” entities and could translate content from a TD into another DRM environment. For example, the DRM client might implement the security portion of the Digital Rights Interface (DRI) that was defined by OpenCable for moving content from a CA/copy protection domain into a DRM domain (e.g., Microsoft DRM). 
       FIG. 4 b    illustrates an exemplary DOCSIS or cable modem (CM) gateway architecture useful with the software architecture of  FIGS. 4-4   a  for providing security download and control functions within an cable network. In the illustrated embodiment, the client-side host  210  uses a DOCSIS “gateway”  450  (comprising both client-side and CMTS-side gateway components  452 ,  454 ) to send information to and from the head-end or BSA hub processes (i.e., AP component  404 ). Specifically, the gateway is used to send/receive download (e.g., DCAS) messages to the host  210  via a CA tunnel formed through the DOCSIS gateway. The gateway also carries traditional Out-Of-Band (OOB) messages generated by or for delivery to the CPE  106 , such as conditional access (CA) messages including entitlements, System Information (SI) messages, Electronic Program Guide (EPG) messages, Emergency Alert System (EAS) messages, etc. The gateway can therefore be considered a multi-channel logical “tunnel” between the CMTS and the CPE  106 . 
     At boot-up, the cable modem (CM) or other DOCSIS-enabled device will establish the appropriate tunnel, as well as ranging, registering and receiving configuration information from the CMTS. The SM driver  436  ( FIG. 4 a   ) requests to pass download messages to the security download bootloader module  432 . The SM driver also requests that the gateway invoke the appropriate tunnels for the CA Client  434 , TD Client  422 , and DRM client  438 . The CPE platform code also establishes an application tunnel for any security downloads (e.g., DCAS client image), as well as any application data. 
     As previously noted, the invention is in no way limited to code or cryptographic element download via the cable modem (CM); however, this often affords a convenient mechanism for doing so, especially when the CM is integrated with the CPE  106  (such as in the “converged” premises device previously described herein. Alternatively, the code and key downloads might be accomplished via in-band channels, such as using the high-speed data download techniques and apparatus described in co-owned and co-pending U.S. patent application Ser. No. 11/013,665 entitled “Method and Apparatus for High Bandwidth Data Transmission in Content-Based Networks” filed Dec. 15, 2004 and incorporated herein by reference in its entirety, in addition to or in place of the cable modem data gateway previously described. This approach allows for data download at accelerated rates via a “point-to-point” approach, wherein a session is established between the receiving entity (such as the CPE  106 ) and the distributing entity (e.g., a head-end server) using one or more allocated QAMs, and a program identifier. Session establishment and data flow control are implemented using protocols and bandwidth that are typically used for delivery and control of video-on-demand (VOD) or similar services, thereby obviating any substantive modifications to the existing network infrastructure. Sessions can be established for the data transfer, and then immediately terminated when the transfer is completed, thereby rapidly freeing up bandwidth on the network as with a conventional OD session. 
     Exemplary CPE— 
       FIG. 5  illustrates a first exemplary embodiment of client premises equipment (CPE)  106  incorporating the security download host  210  functionality of the present invention. As shown in  FIG. 5 , the CPE  106  comprises an OpenCable-compliant embedded system with integrated RF front end  502  (e.g., tuner stage, demodulator, etc.), cable modem (CM)  504 , host digital processor (e.g., microprocessor)  506 , RAM  508 , mass-storage device  510 , and a plurality of back-end interfaces  512  (e.g., video/audio interfaces, IEEE-1394 “Firewire”, USB, serial/parallel ports, etc.) for interface with other end-user apparatus such as televisions, personal electronics, computers, WiFi/PAN or other network hubs/routers, etc., and for distribution of content or signals to one or more SODs or NSODs. The interfaces  512  may also be configured to receive data or signals from connected devices within the SODs or NSODs. While shown as an integrated device, it will be readily apparent that these components may be provided separately, and even exist in different locations so long as security requirements and policies are maintained. 
     The CPE  106  also optionally includes a recording device (e.g., DVD burner)  525  useful for recording the user&#39;s media, as well as (optionally playing it back after recording). 
     Other components which may be utilized within the device (deleted from  FIG. 4  for simplicity) include FIFO or buffer memory (which may be implemented in RAM or otherwise), direct memory access (DMA) units, various processing layers (e.g., DOCSIS MAC or DAVIC OOB channel, MPEG, etc.) as well as media or network processors (NPs) and other specialized SoC or ASIC devices. These additional components and functionality are well known to those of ordinary skill in the cable and embedded system fields, and accordingly not described further herein. 
     The host  210  associated with the CPE  106  of  FIG. 5  further comprises a secure microprocessor (SM)  514  in data communication with a transport processor (TP)  516 , each of the foregoing comprising an integrated circuit in the exemplary embodiment. It will be appreciated that while shown as separate devices, the SM, TP and host microprocessor  506  can be physically integrated into a common form factor or chip (e.g., SoC device) if desired. 
     The device  106  of  FIG. 5  may also be provided with an OCAP-compliant monitor application and Java-based middleware which, inter alia, manages the operation of the device and applications running thereon. It will be recognized by those of ordinary skill that myriad different device and software architectures may be used consistent with the invention, the device of  FIG. 5  being merely exemplary. For example, different middlewares (e.g., MHP, MHEG, or ACAP) may be used in place of the OCAP middleware of the illustrated embodiment. 
     The host processor  506  and internal bus and memory architecture of the CPE  106  of  FIG. 5  are ideally adapted for high-speed data processing, at least sufficient to support the client-side processing tasks necessary to implement the DCAS/TD/DRM download and configuration functionality of the present invention effectively and without significant latency. This may be accomplished, e.g., through a single high-speed multifunction digital processor, an array of smaller (e.g., RISC) cores, dedicated processors (such as a dedicated MPEG media processor and interface controller), etc. in addition to the SM  514  and TP  516  used for specific security-related functions as described below. 
     In the illustrated embodiment, the SM  514  is in direct or indirect data communication (e.g., via the DOCSIS gateway previously discussed) with the network AP  208  which is disposed at, e.g., the head-end  150  or the BSA hub site. The AP authenticates the CPE (via its SM  514  and other relevant data), thereby allowing the download protocol to proceed. 
     Once authenticated, the SM  514  is configured to securely perform the download protocol (described subsequently herein), generate and store keys and other cryptographic elements, store CA data. See  FIG. 4 b    for an exemplary software and firmware configuration for the SM  514 . In the illustrated embodiment, the SM is programmed and keyed by the TA (via the AP and other network components) as previously described with respect to  FIG. 2 . 
     The TP  516  is configured to receive encrypted content (e.g., video) or other data from the distribution network  101 , and decrypt this content/data using indigenous decryption capabilities (e.g., a public/private key pair). The SM  514  is configured to receive conditional access (CA) data from the network (or via another delivery mechanism) in order to enable the decryption by the TP (i.e., recovery of the control words needed to decrypt the content). 
     The exemplary embodiments of the CPE  106 , when used in conjunction with the network architecture previously described, advantageously eliminate the need for physical media or devices (e.g., a “CableCard” or the like). Rather, the user and network operator are provided with a CableCard-like functionality, yet using a network download paradigm, and even when only unidirectional communication is available. This configuration also supports a retail business model (i.e., sale of STBs or other such CPE at the retail level, such as by third-party manufacturers), as well as OEM devices present in the installed customer base. 
     As part of the application layer  416  of the CPE  106  (see  FIG. 4 b   ), various different types of client applications may be running (or operable to run) consistent with the present invention. In one embodiment, a separate (dedicated) client application adapted for DCAS or other security download functions may be provided. This application provides the CPE user with an interface to the security download system, such as for the entry of information, status information, troubleshooting, etc. This may include, e.g., a separate GUI or other type of UI, and may operate substantially independent of other applications on the CPE  106 . Alternatively, this functionality may be integrated into one or more existing or downloadable applications (such as a VOD application, “Watch TV” application, navigator, TV-commerce application, or even EPG). 
     As yet another option, the download and security configuration functionality may be completely transparent to the end user, such as where the DCAS/TD/DRM components running on the CPE  106  provide all necessary messaging, inputs, and call functions to update or reconfigure the CPE  106 . 
     The CPE middleware and any other relevant components may also be modified in order to provide a “universal” software interface for at least certain aspects of the security download functions, such that application developers can write their applications to make use of these aspects. Similarly, the “universal” CPE described in co-pending and co-owned U.S. patent application Ser. No. 10/782,680 filed Feb. 18, 2004 and entitled “Media Extension Apparatus And Methods For Use In An Information Network”, incorporated herein by reference in its entirety, may be used consistent with the present invention in order to allow specific features and extensions (e.g., Java or JMF extensions) to be configured by a particular MSO or other entity when the CPE is used in their network. 
     Various indications are optionally utilized within the hardware environment of the CPE  106 , including e.g., an LED or other indicator to show cable modem link and activity, power status, LAN-802.3 activity on one or more Ethernet ports (if installed), etc. Furthermore, a “soft” display (e.g., TFT or LCD display having software generated indications) may be used on the CPE  106  (or a remote device in communication therewith) to provide a flexible display environment. The methods and apparatus of co-owned and co-pending U.S. patent application Ser. No. 10/773,664 filed Feb. 6, 2004 entitled “Methods And Apparatus For Display Element Management In An Information Network”, incorporated herein by reference in its entirety, may be used within the CPE  106  or other communicating devices. Specifically, display elements such as GUI windows or discrete indicators in a client device running multiple related or unrelated applications can be managed and controlled. In one embodiment, an improved window management entity is provided within the device with which HAVi-compliant application(s) can interface in order to access display elements according to a priority structure or hierarchy. One or more privileged applications are designated and allowed to affect the priority structure, including requesting a new in-focus application to be placed atop the priority structure. The network operator can also optionally control the operation of the window manager remotely via a network agent. 
     The CPE  106  mass storage device  510  of the illustrated embodiment comprises a Serial-ATA (SATA) or Ultra-ATA (also known as Ultra-DMA, or ATA-4/5/6/7) hard disk drive for the operating system and content storage of at least 300 GB, although higher or lower capacities and even RAID arrays may be used for this purpose. The CPE is also optionally configured allow for an external USB (e.g., USB 2.0) drive to be attached and automatically added to the existing storage. It will also be appreciated that USB keys of the type well known in the art can be used consistent with the USB port(s) of the CPE  106 , so as to make the data storage device highly mobile and of very small size. 
     The RF front end  502  of the CPE may comprise a traditional video RF front end (e.g., tuner) adapted to receive video signals over, e.g., a QAM. For example, one exemplary embodiment of the RF front end  502  comprises one or more tuners, a demodulator, decryption module, and demultiplexer of the type well known in the art, although other configurations may be used. A wideband tuner arrangement such as that described in co-owned and co-pending U.S. patent application Ser. No. 11/013,671 entitled “Method and Apparatus for Wideband Distribution of Content” filed Dec. 15, 2004 and incorporated herein by reference in its entirety, may also be utilized, such as where the content associated with one or more program streams is distributed across two or more QAMs. Additionally, the RF front end  502  modulates, encrypts/multiplexes as required, and transmits digital information for receipt by upstream entities such as the CMTS or a network server. 
     It will also be recognized that the present invention may be used in conjunction with a number of different capabilities and features useful with traditional CPE functions. For example, the error logging and reporting methods and apparatus described in co-owned and co-pending U.S. patent application Ser. No. 10/722,206 entitled “Methods and Apparatus for Event Logging in an Information Network” filed Nov. 24, 2003, which is incorporated herein by reference in its entirety, may be used within the CPE of  FIG. 5 . For example, the aforementioned disclosure describes methods and apparatus (including APIs) for logging errors that occur on client devices or CPE  106 . In the present context, these errors may include errors generated within or by the CA, DRM, or TD clients, SM or TP, etc., which can then be transmitted upstream to a responsible entity (e.g., AP  208 , management node, conditional access server  304 , etc.) for further analysis or correction. 
     Similarly, the hardware registry apparatus and methods described in co-owned and co-pending U.S. patent application Ser. No. 10/723,959 entitled “Methods and Apparatus for Hardware Registration in a Network Device” filed Nov. 24, 2003, also incorporated herein by reference in its entirety may be used consistent with the present invention. This disclosure provides apparatus and methods for control of hardware within a networked electronic device (e.g., CPE) through use of a hardware registry. The registry contains records that correspond to an optional set of hardware functionality (e.g., personal video recorder). Each record (or set of records) may contains fields that: (i) identify the type of circuitry and peripherals, (ii) uniquely identifies circuitry and peripherals of the same type, (iii) specify parameters that are specific to the circuitry and peripherals types, and/or (iv) contain a reference to an application programming interface that can be used to access and manipulate the circuitry and peripherals. In one exemplary configuration, the CPE  106  is adapted to provide control over Host CORE optional circuitry for a digital video recorder (DVR) and digital video interface (DVI). A DVR/DVI application can therefore be downloaded to retail or leased set-top boxes and other consumer electronics equipment, which provides control of any available DVR/DVI circuitry found therein or functions associated therewith. This not only permits “after-the-fact” control of optional hardware features in a retail (third party) electronics device by the MSO or other system operator, but also allows for control and reconfiguration of leased devices after distribution to the end user(s). The CPE  106  described herein may either be of third-party or leased origin, and hence may benefit under either model when used in conjunction with the foregoing hardware registry approach. 
     The software interface management apparatus and methods described in co-owned and co-pending U.S. patent application Ser. No. 10/883,374 filed Jun. 30, 2004 and entitled “Apparatus And Methods For Implementation Of Network Software Interfaces”, also incorporated herein by reference in its entirety, can be used within the CPE  106  or associated devices. Specifically, in one embodiment, network-specific programming interfaces (e.g., APIs) may be downloaded to the CPE, registered, authenticated, stored and executed in a software protocol stack implementing OpenCable Application Platform (OCAP) or Multimedia Home Platform (MHP) standards. The host device software comprises a “manager” module that registers APIs identified by the OCAP Monitor Application, such that all applications launched thereafter on the device can use these communications APIs, provided they have the appropriate permission(s). This relieves individual applications from having to support details regarding network-specific protocols and APIs. In an alternate embodiment, class and data files associated with the API functionality are downloaded along with an application. The downloaded application registers the API using a modified version of the API using a description file (DF). The DF describes the class and data files provided with the application that are part of the registered API. 
     In another aspect, the CPE  106  of the present invention is also compatible with the methods and apparatus disclosed in U.S. patent application Ser. No. 11/363,578 filed Feb. 27, 2006 and entitled “Methods And Apparatus For Selecting Digital Access Technology For Programming And Data Delivery”, which is incorporated herein by reference in its entirety. Specifically, electronic devices such as set-top boxes, PMDs, or other types of equipment containing one or more hardware and software functions or modules are used; the hardware and software functions/modules of the different devices on the network contain various capabilities and options, including conditional access capabilities, DRM capabilities, video coding or compression capabilities, encryption schema, and network interfaces. These capabilities are utilized as a basis for determining which conditional access, DRM, coding, encryption, and/or network interfaces to utilize for delivery of content to each particular client device. The CPE  106  of the present invention can accordingly be equipped with such capability if desired in order to, inter alia, profile the CPE for tailoring content or other functions (e.g., CA, DRM, etc.) to that specific CPE environment. 
     As previously noted, the client device (e.g., CPE  106 ) may take any number of forms, including for example a converged device or “hive” such as that described in co-pending U.S. patent application Ser. No. 11/378,129 filed Mar. 16, 2006 previously incorporated herein. This converged device comprises a remotely manageable premises device that, inter alia, acts as a centralized client networking platform providing gateway services such as network management as well as traditional content and high-speed data delivery functions. The converged device also acts as the shared internet (e.g., Internet) connection for all devices in the premises via a cable modem or other such interface, sharing personal and DVR content such as video, music and photos (and any associated metadata) throughout the premises, and providing both a wired and wireless network in the home. Telephony services utilizing e.g., embedded multimedia terminal adapter (eMTA) and/or WiFi architectures may also be provided via the device; these services can make use of the network operator&#39;s indigenous VoIP or comparable telephony capability if desired, thereby providing an even more unified service environment. 
     The converged premises device can also provide a trusted domain (TD) for content or data, as well as allowing a subscriber total mobility in the home by not limiting content or data to any one viewing/access location. For example, content or data may be accessed on any monitor in the premises, as well as on a PC or personal media device (PMD). 
     A wired home network utilizing existing coaxial cable in the premises is also created, using e.g., an Ethernet-to-coaxial bridge technology based on the MoCA specification. This will allow existing devices and DVRs to connect and share content with the CPE, and also allows the network operator (e.g., MSO) to control and manage the premises coaxial network. 
     Secure Download System (SDS) Messaging and Protocol— 
     The host  210  of the exemplary embodiment is configured to provide appropriate routing of secure download system messages (described in greater detail below), as well as other desired functions, in a secure and efficient manner. Specifically, the host architecture of the invention: (i) enables network discovery and mutual authentication of newly attached or configured host devices via e.g., the SM bootloader  432 , which provides information regarding the identity of the SM  514 , cryptographic keys, and key pairing; (ii) enables the AP  208  to detect hosts running the “wrong” CA, DRM, or TD client and remedy the problem remotely; (iii) enables mutual authentication between the AP  208  and the SM bootloader  432 , and registration of the SM with the AP, in order to permit secure image or key download and other functions; (iv) verifies successful SM Client (e.g., CA, DRM or TD client) installation, and retention by the AP  208  or its designated proxy of the installed SM Client version once the installation is complete; and (v) authenticates download system messages. Moreover, the exemplary host architecture is configured to permit TA verification of TP/SM key pairing, and request new keys as necessary. 
     In one embodiment, the secure download process previously described herein is based on mutual authentication between the AP  208  and the SM bootloader module  432  based on random challenges and trusted signatures. This approach advantageously reduces the risk of packet replay and man-in-the-middle (MITM) attacks. The exemplary AP  208  and the bootloader  432  are configured to implement secure download messaging and functions as a state-machine, wherein progression of the state machine to a subsequent operation is predicated on successful verification of the received message and any associated data in a current operation. This approach prevents attackers from replaying packets from earlier in the sequence while the state machine is executing. In one embodiment, the SM  514  is configured to digitally sign all outgoing messages, and verify the signature on all incoming messages, thereby further frustrating surreptitious attempts at replay or MITM attack. 
     Each message used within the secure download protocol of the exemplary embodiment comprises the following components: (i) message header; (ii) message payload or content; (iii) message attachments; and (iv) message signature. 
     The message header is used by the message recipient to determine the type of message, and receive a unique identifier and information as to the structure of the message. The message header precedes the other message components, and can be unencrypted since it does not carry any sensitive information. 
     The message content portion contains message-specific fields, digital signatures, and cryptographic elements (e.g., keys). This content portion is constructed according to a specific message format unique each message. After key exchange is successfully completed, all message content is encrypted by the sender using the recipient&#39;s public key portion. 
     The message attachment(s) are each associated with a cryptographic element (e.g., symmetric key) within the message content. 
     Appendix I hereto describes an exemplary message format according to one embodiment of the invention. 
     Exemplary embodiments of these messages are now described in greater detail, although it will be appreciated that other message types, functions, and in fact protocols may be used consistent with the broader principles of the invention to effect these functions. 
     In one embodiment of the invention, notification or “announcement” messages are used for inter-entity communication within the security architecture of  FIG. 2 . These messages are sent by the AP  208  or a designated proxy to indicate the most current set of SM Client (i.e., TD, DRM or CA client) images and security information for use in the download process. The SM (e.g., bootloader routine  432 ) receives and processes these announcement messages via the messaging interface and the DOCSIS gateway of  FIG. 4 b   . If a change in the SM Client or keys (or other change) is indicated for the SM  514  of the designated CPE, then the bootloader  432  completes the key request, host authentication and download processes as required to effect these changes. 
     The exemplary protocol provides two messages that can be used to cause the bootloader  432  to download one or more SM Clients for use on the SM  514 : All secure download system messages received by the monitor  480  are forwarded to the bootloader  432  for additional processing thereby. 
     Authentication messages are used by the secure download architecture to perform mutual authentication between the SM  514  of the CPE  106  and the AP  208  at the head-end  150 , BSA hub site, etc. After authentication, the AP  208  knows the state of the SM  514  on the CPE  106 , and can direct the SM  514  to download the appropriate cryptographic keys and/or SM Clients (i.e., DRM, TD, or CA clients  438 ,  422 ,  434  as shown in  FIG. 4 b   ). Additionally, the SM bootloader module  432  is given the set of SM Clients that the AP  208  requires to be installed on the CPE. The SM evaluates the current (requested) configuration of the CPE  106 ; if this does not match the currently installed SM Client set, the SM bootloader  432  will receive new or replacement SM Clients via the download protocol previously described herein. 
     The authentication messages issued from the SM bootloader  432  can also be used to provide platform or device-specific information in the event that an SM is migrated between different APs (i.e., from one network to another). This allows for the new network to uniquely and affirmatively identify the CPE via its SM  514 . 
     Key management messages also may be used to convey the correct AP keys and the associated AP key chain from the TA  203  to the host  210  on the CPE  106 . 
     Download messages are used by the secure download system to deliver download data (including the SM Client image(s)), and to confirm successful image download and installation on the CPE by the SM bootloader  432 . In the exemplary embodiment, these messages comprise a first or “download” message (e.g., DownloadInfo) and second or “confirm” message (DownloadConfirm). The SM  514  can receive and install one SM Client image  422 ,  434 ,  438  through each DownloadInfo and DownloadConfirm message sequence, although other protocols, including multiple images per sequence, are feasible with the invention. The download message sequence can be repeated until the SM  514  has a set of client applications that match that specified by the relevant AP  208 . 
     The download messages also may be configured to contain instructions or other data that can be used to control the installation and launching of the SM Clients  422 ,  434 ,  438 , as well as providing status information after each client module is downloaded and installed. 
     Status or log messages are used by the AP  208  in the exemplary embodiment to obtain a current information log from the SM  514 . The information log comprises a plurality of entries and is stored in the SM  514  or another designated location within the TD. A FIFO approach (i.e., new data pushing out old data) can be used for log entries if desired, especially where storage space is constrained. The AP  208  can also be configured to provide selection criteria in order to filter the log entries to be returned by a log message request, thereby economizing on upstream bandwidth consumption and messaging overhead. The log entries may be retrieved by the AP  208  or its proxy at any time after its keys have been successfully installed in the SM  514 , thereby ensuring that the AP has unimpeded access, while also unauthorized access to the log is frustrated. 
     The exemplary embodiment of the security management and download protocol described herein further supports metadata (e.g., XML or the like) or other comparable data structures, as well as provision of Content Management Information (CMI) used for, inter alia, content rights signaling. In the present context, “metadata” comprises extra or supplementary data not typically found in primary content or signaling (or at least not visible to the users of the network). Specifically, for certain components of primary content (e.g., video/audio/data) or messaging, one or more metadata structures are included or appended that provide additional information related to that content or message for that content. This metadata can be provided with the content from its source or provider (e.g., a network studio or station or the like), or alternatively added by the network operator e.g., via the security apparatus described with respect to  FIGS. 2-3   d  herein. Various permutations and mechanisms for generating, adding and editing metadata will be recognized by those of ordinary skill, and hence are not described in greater detail herein. In the exemplary embodiment, the metadata is used for control or indication of the usage of content while in the TD, but may be used for other purposes as well. 
     Methods 
     Referring now to  FIG. 6 , a first exemplary embodiment of the generalized method of conditional access (CA) trusted domain (TD), and/or digital rights management (DRM) configuration and update using the secure download system of the invention is described. 
     As shown in  FIG. 6 , the method  600  generally comprises first providing one or more new or updated images (software) for transmission from one node of the network (e.g., head-end, hub site, third party designated server, etc.) to another node (e.g., CPE  106 , converged premises device, enterprise gateway or proxy, etc.) wherein a trusted domain exists or is to be established (step  602 ). These images may comprise the aforementioned common SM Client image, the personalized image, or both (or others). 
     Per step  604 , the image(s) is/are securely transmitted directly or indirectly from the first node to the second node. Here, the “secure” transmission may include, without limitation, (i) encryption and encapsulation for transmission (e.g., VPN tunneling) over a physically non-secure or untrusted network such as the Internet or other distribution network; (ii) transmission over an end-to-end physically secure network; or (iii) delivery via another secure mechanism (e.g., service personnel, encrypted physical media, etc.). Mechanisms for authentication, encryption, data integrity, anti-spoofing protection, man-in-the middle protection, anti-replay protection, denial of service protection, and the like may also be utilized to any desired degree as part of this transmission process in order to frustrate attempts at compromise of the secure image, diversion to unauthorized parties, etc. 
     Per step  606 , the secure image is received by the target device e.g., CPE  106 , accessed (which may involve decryption and/or decoding), and installed on the desired platform. This platform may be the CPE  106  itself, or another connected device within the perimeter of the trusted domain that has authenticated itself to the CPE  106  (whether directly, or acting as a proxy for the distributing entity) and which meets the requirements of having an SM  514  and supporting the secure download protocol and requirements previously described. 
     Lastly, the target device is configured or operated using the secure image(s) per step  608 . Such configuration operation may take the form of establishing a trusted or authorized service domain within the device, configuring components within the device (e.g., secure microprocessor, transport processor, etc.), facilitating further communications, decryption of other encrypted keys, providing access to the private portion of a public/private key pair, decrypting/encrypting content, establishing security policies for one or more SODs or NSODs connected to the CPE  106 , etc. 
     Referring now to  FIG. 6 a   , one specific embodiment of the generalized methodology of  FIG. 6  is described in detail. It will be appreciated that while the embodiment of  FIG. 6 a    is described in the context of a conditional access (CA) system of a cable television network, the principles of the methodology are more broadly applicable to TD and DRM configuration and updates, as well as other types of networks such as, without limitation, satellite networks and IP-based networks. 
     Per step  612  of the method  610  of  FIG. 6 a   , the secure image to be provided is generated. This image may comprise, for example a secure client application (e.g., CA client  434  of  FIG. 4 b   ), O/S component, middleware or target platform component, or other module adapted to provide the desired functionality. In one embodiment, the image(s) are rendered as comparatively small (e.g., &lt;80 kb) code modules that perform cryptographic key recovery/generation as well as validation. The actual decryption/encryption of content takes place in the transport processor. The image(s) can be common to all targeted delivery devices (e.g., common client images discussed previously), and/or may be uniquely configured based on one or more parameters associated with the target installation. For example, one personalized image may be used for CPE (e.g., DSTBs) of Type A, while a second image is used for Type B CPE. Alternatively, one image may be used for subscribers of a given class or service level, while another image is used for those of a different service level (e.g., one image providing greater capabilities, functions, and/or portability, etc. for the higher service level subscribers). The images may also be divided along functional lines as previously noted; e.g., CA/DRM/TD. The present invention accordingly contemplates that the secure Client image(s) delivered to the target platform(s) can range between being completely ubiquitous or common to all targets, to being completely unique to each different target platform or subscriber, and combinations thereof (e.g., common and personalized images delivered contemporaneously). This level of granularity can advantageously be controlled by the MSO or network operator as desired, and can be subject to higher-level management processes (see discussion of business rules engine below). 
     It will also be appreciated that the generation or deployment of the secure image(s) to a distribution node (e.g., head-end AP  208  or BSA hub site) can be conducted in advance of distribution to the targeted platforms, or alternatively in near-real time upon request. For example, in one variant of the invention, the MSO is aware of the inventory of devices on its network (i.e., how many of what types of devices are connected, and which individual subscribers possess them), and accordingly can preposition corresponding variants of the secure image files for use by the AP  208  in configuring or updating CPE  106  on the network. Hence, when a Scientific Atlanta 8XXX DSTB with XYZ brand Model 123 SM is targeted for update, the AP will select the correct or matching variant of the secure image for this device (such as via a carousel mechanism) and perform any additional provisioning of the image(s) before download to the target device(s). 
     Consider alternatively the case where a new-model (e.g., retail) CPE  106  is coupled to the network, and requires update or configuration via the DCAS. In such a case, the AP  208  may not have immediate access to a secure image appropriate for this device, and hence must either (i) access the appropriate image from another source (e.g., third party site, etc.), or (ii) generate and prepare the image “on the fly” for delivery to the target platform(s). Both of these functions may be performed in a highly automated fashion; e.g., by a software environment running within the AP  208  or other SDS components adapted to generate the secure image(s) based on information provided by the AP  208  and the CPE  106  itself. To this end, the CPE  106  may actually be dynamically profiled as to its hardware and software capabilities (such as via a profiling message issued by the AP or its proxy), and the gathered profiling information transmitted to the AP for use in generating the secure image. For example, the profiling message may indicate that the target CPE  106  has only n Gb of RAM available, has an XYZ Model 123 SM, or has limited processing capability, and hence the secure image selected for that device must meet certain limitations on code size and construction. 
     Per step  614 , the CPE  106  is discovered by the DCAS AP  208 . This can be accomplished by existing communication protocols used for other purposes (e.g., downstream/upstream OOB or in-band messaging), or alternatively using a dedicated protocol for this purpose This discovery may occur after the secure image is made available, before the secure image is generated “on the fly”, or contemporaneous with secure image availability, as previously described. 
     Next, the CPE  106  is authenticated by the AP, including authentication of the SM  514 , which is the target of the secure image and cryptographic element download (step  616 ). 
     Next, the conditional access system (CAS) download key is sent to the CPE  106  via DOCSIS downstream channels, or alternatively another delivery channel (e.g., in-band or OOB, satellite link, third-party WSP or CSP, etc.) per step  618 . For example, an entitlement control message (ECM) of the type known in the CA arts or other such mechanism may be used as the delivery mechanism for the key. This key may comprise, for example an encrypted symmetric aor asymmetric key or other such cryptographic element. Whatever type of cryptographic keying is used, it will typically be desirable to encrypt the download key for added security. 
     The encrypted CA Client image  434  is also downloaded to the CPE  106  via DOCSIS downstream channels, or alternatively another delivery channel per step  620 . This download may be conducted simultaneously via the same channel as the download key, simultaneously via a different channel from that used for the key, or at a different time using the same or a different channel. As previously noted, mechanisms for authentication, encryption, data integrity, anti-replay or spoofing, etc. may be employed as part of the download key and/or secure image transmission processes in order to frustrate surreptitious access to either or both components. 
     In the exemplary embodiment, the CAS download key comprises the public part of a public/private key pair, and the private key part (maintained within the trusted domain of the target CPE  106 , namely the SM  514 ) is used to decrypt the download key (step  622 ). The decrypted download key enables the CPE  106  to unlock the encrypted CAS image (software) per step  624 . 
     The decrypted CA software is then loaded or installed onto the CPE (or other designated target platform within the trusted domain) per step  626 , and the CPE  106  or target platform configured or operated using the software per step  628 . 
     Alternatively, the private portion of the key pair may be transmitted to the target device (using methods for delivery of the encrypted public portion as previously described), and the public portion may be maintained at the target device. 
     With respect to content (e.g., video) encryption/decryption, the following exemplary protocol ( FIG. 6 b   ) is utilized in order to protect content and keys, and selectively allow access to encrypted content. 
     In one embodiment, Entitlement Management Messages (EMMs) are used to specify which CPE  106  within the network (“targeted populations”) are given access to content per step  650 . A targeted population may comprise as few as one specific CPE, or as large as all CPE within the network. Typically, however, EMMs will be issued to a group of CPE based on one or more targeting criteria which may include, without limitation, specific TUNER ID, MAC or other CPE-specific variables, geographic profiles (e.g., all CPE within a given geographic region, zip code, etc.), demographic profiles, equipment type profiles, subscriber level profiles, CA and DRM capabilities, and so forth. Exemplary methods and apparatus for targeting selected subsets or populations with a network are described in, e.g., co-pending and co-owned U.S. patent application Ser. No. 11/186,452 entitled “Method And Apparatus For Boundary-Based Network Operation” filed Jul. 20, 2005 which is incorporated herein by reference in its entirety, although other approaches may be used with equal success. 
     Entitlement Control Messages (ECMs) are used in the exemplary embodiment to, inter alia, carry the keys for descrambling or decryption of the actual content (e.g., MPEG2 video) as distinguished from the software image(s). One or more designated sources (e.g., network QAMs) sends three (3) items to the CPE  106 : (i) an encrypted EMM key (also known as a “service key”) per step  652 ; (ii) an encrypted ECM key (also known as the “session key” or “transport key”) per step  654 ; and (iii) an encrypted stream of content data (step  656 ). The content stream may be encrypted using, e.g., the well known Digicipher II or PowerKey approaches, although other techniques may be used with equal success. 
     Next, per step  658 , the host  210  of the CPE  106  decrypts the EMM or service key using a private key portion stored on the CPE  106  within the CA client (SM  514 ). The decrypted key contained from the EMM is then used to decrypt the ECM per step  660 . The decrypted key from the ECM is then used to decrypt the encrypted stream of content/data (step  662 ), resulting in a “clear” video or data stream. 
     It will be appreciated that the security download architecture of the present invention can also be used in a complementary or layered fashion with other content acquisition, management and control technologies. For example, the methods and apparatus described in co-pending and co-owned U.S. patent application Ser. No. 11/080,693 filed Mar. 14, 2005 entitled “Method And Apparatus For Network Content Downloading and Recording”, incorporated herein by reference in its entirety, may be used consistent with the present invention to provide network users with the ability to purchase and record content to a physical medium, while also obeying the security policies imposed by the download (e.g., DCAS) security architecture herein. This disclosure also provides mechanisms for the inclusion of digital copyright data within the recorded data/content, such as well-known digital watermarking data of the type authorized under the United States Digital Millenium Copyright Act (DMCA). For example, Digimarc®, SysCoP™, EIKONAmark™, and other similar commercially available watermarking approaches can be used. Various types of steganographic approaches may also be employed consistent with the invention in order to enforce copyright and provide the copyright owner with accountability and/or trace-ability of reproduced versions of their copyrighted material. If desired, these approaches can be readily coded into the software or firmware of the recording device such that the inclusion of this data is completely transparent to the user, and does not require any user or MSO/content provider intervention. 
     This layered or multi-faceted approach may also provide enhanced protection by virtue of not only protecting the content within the TD and controlling how it is distributed outside of the TD (such as into a SOD), but also physically protecting the media itself via watermarking, inclusion of DRM content into the “burned” ROM or other media, etc. 
     Moreover, this combination is also potentially quite powerful from the standpoint that the operational flexibility and security provided by the download architecture of the present invention, when coupled with the ability to provide content earlier to network subscribers than would otherwise be available over that network (via the technology described in the aforementioned disclosure), provides functionality that could not otherwise be obtained; i.e., the ability to download and physically reproduce content that is commensurate with that available in a retail or rental outlet, yet over their cable network, and with the ability to distribute the content to other “approved” devices within their premises network seamlessly while also affording the network operator (or third party content source) control over the distribution process. 
     Business/Operational Rules Engine and Methods— 
     In another aspect of the invention, a processing entity (e.g., rendered as one or more computer programs disposed within the head-end (e.g., AP  208 , PS  306 , etc.), BSA hub entity, CPE  106 , or other location) includes a so-called “rules” engine. This engine comprises, in an exemplary embodiment, one or more software routines adapted to control the operation of the security management architecture in order to achieve one or more goals relating to operations or business (e.g., profit). Included within these areas are implementation of security management policies that can increase network optimization and reliability, increase maintenance intervals, increase subscriber or user satisfaction, increase subscription base, higher profit (e.g., from increased advertising revenues, more subscriber “views” of given content, higher data download speed, increased bandwidth and responsiveness to changing demands for bandwidth, reduction of undue QAM replication, and so forth. 
     These rules may comprise a separate entity or process, and may also be fully integrated within other processing entities (such as the aforementioned security management architecture of  FIGS. 3 a -3 d   ), and controlled via e.g., a user interface such as a GUI on a PC connected to the relevant device. In effect, the rules engine comprises a supervisory entity which monitors and selectively controls security management operation processes at a higher level, so as to implement desired operational or business rules. The rules engine can be considered an overlay of sorts to the more fundamental algorithms used to accomplish required security functions and network operation, such as key management, encrypted image generation, TD/ASD or DRM configuration, IP address assignment, statistical multiplexing, BSA switching, and so forth. 
     For example, the network security management apparatus (or CPE) may invoke certain operational protocols or decision processes based on information or requests received from the CPE, conditions existing within the network, demographic data, geographic data, etc. However, these processes may not always be compatible with higher-level business or operational goals, such as maximizing profit, bandwidth management, or system reliability. Hence, when imposed, the business/operational rules can be used to dynamically (or manually) control the operation of the download and/or Client process on the CPE or within other domains (e.g., SOD or NSODs in communication with the TD). The rules may be, e.g., operational or business-oriented in nature, and may also be applied selectively in terms of time of day, duration, specific local areas, or even at the individual user level (e.g., via specific identification of the CPE or client device via TUNER_ID, MAC address, SM identifying information or the like). 
     For example, one rule implemented by the rules engine may comprise only providing certain types or program recording and/or distribution features to certain subscribers or classes of subscribers. The subscriber CPE  106  may possess a Firewire (IEEE-1394) interface or other such interface capable of transmitting content to a connected device for example, but the ability to transfer such protected content out of the TD not be made available to such subscribers unless they met certain criteria (e.g., “premium” subscription, etc.). 
     Another rule might impose a moratorium or restrictions on downloading secure images (e.g., SM Clients) or download keys to the CPE  106  during conditions of very heavy loading, e.g., until a certain minimum threshold of available bandwidth is present, thereby avoiding contention for bandwidth resources with “premium” services such as DOCSIS cable modem Internet access. Similarly, processing typically done upstream of the CPE could be dynamically shifted to the CPE under such circumstances so as distribute the processing load (and hence downstream messaging bandwidth consumed) to the CPE. 
     Similarly, another rule might comprise controlling and rate-limiting the region over which any bulk upgrade of SM Client images is performed (see discussion of  FIGS. 3 e -3 n    above) in order to limit the amount of network traffic and host resource load added during SM Client image downloads. 
     Premium subscribers might also be given “head of the line” privileges where any contention exists for SM Client download requests or keying (such as by way of a “bottleneck” at the TA  203 ). 
     Moreover, premium subscribers might be given a greater scope of options and choices; e.g., the ability to use a wider range of CPE (e.g., new DSTBs introduced in the retail market), while more basic subscribers are limited as to the type of device they may use as part of their subscription. 
     The establishment of a trusted domain, conditional access perimeter, and/or digital rights policies may also be made in a substantially dynamic fashion using the methods and apparatus of the invention. For example, an MSO might know that a given subscriber or premises might only use recording or personal media devices (PMDs) during certain time periods (e.g., weekends) based on, e.g., historical data, subscription restrictions, or other operational factors or conditions. Hence, extension of the TD to include these capabilities, and necessary permissions, can be selectively enabled or disabled by the MSO if desired, such as to achieve other operational or business goals. This can also be useful for maintenance modes, wherein such maintenance is scheduled into periods when the subscriber is not expected to make use of these features during a particular period of time. These capabilities can also be rapidly re-established should the subscriber wish to utilize them (e.g., in an “on-demand” fashion). 
     The present invention also lends itself to various business models in terms of distribution, operation, and service provision. Specifically, by using the technology of the present invention, the CPE  106  can also be reconfigured as a trusted domain for protected content received over the cable or satellite receiver (tuner). New versions or upgrades of software/firmware can readily be downloaded and installed as well. In that the present invention advantageously provides MSO control over the access, distribution and reproduction of content within the network (and to a degree beyond the MSO network), numerous different permutations of these features can be offered by the MSO as part of a subscription or incentive program. For example, a “basic” subscriber might be given a certain limited package of TD capabilities (e.g., no transmission of protected content outside of the TD, no recording to fixed media such as a CD-ROM, no “multi-room” DVR, etc.), while a higher level subscription package might include these capabilities, and yet others. Individual or groups of features or capabilities may also given to subscribers or prospective subscribers for limited periods of time, or under certain limited circumstances, as an incentive or trial. 
     One variant of the business methodology of the invention contemplates delivery of substantially similar or “generic” hardware/firmware environments to all subscribers, with the MSO able to tailor the CA, TD and DRM capabilities of their individual CPE  106  for their particular subscription level, needs and premises. For example, some users may have local recording devices (e.g., DVR or the like) which may require configuration of the trusted domain to extend to these devices to permit subscriber purchase and in-home “burning” of content according to the methods previously discussed with respect to U.S. patent application Ser. No. 11/080,693. 
     As can be appreciated, literally an unlimited number of different premises/subscriber-specific configurations may be employed consistent with the security download capability of the invention, and hence it is typically more economical and efficient to allow MSO reconfiguration of a substantially generic device, as opposed to custom configured hardware or software for each subscriber/premises. 
     It will be recognized that while certain aspects of the invention are described in terms of a specific sequence of steps of a method, these descriptions are only illustrative of the broader methods of the invention, and may be modified as required by the particular application. Certain steps may be rendered unnecessary or optional under certain circumstances. Additionally, certain steps or functionality may be added to the disclosed embodiments, or the order of performance of two or more steps permuted. All such variations are considered to be encompassed within the invention disclosed and claimed herein. 
     While the above detailed description has shown, described, and pointed out novel features of the invention as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the invention. The foregoing description is of the best mode presently contemplated of carrying out the invention. This description is in no way meant to be limiting, but rather should be taken as illustrative of the general principles of the invention. The scope of the invention should be determined with reference to the claims. 
     
       
         
           
               
             
               
                 APPENDIX I 
               
             
            
               
                   
               
               
                 EXEMPLARY SECURE DOWNLOAD 
               
               
                 INFRASTRUCTURE INTERFACES 
               
            
           
           
               
               
               
               
            
               
                 Interface 
                 Components 
                 Description 
                 Security 
               
               
                   
               
               
                 SDS-SRXI 
                 TA-LKS 
                 The SDS Secure Records Exchange Interface is 
                 HTTPS/TLS 
               
               
                   
                   
                 used for the bulk distribution of Key 
                 Mutual 
               
               
                   
                   
                 information between the Trusted Authority 
                 authentication using 
               
               
                   
                   
                 Key information database to a Local Key 
                 TA signed 
               
               
                   
                   
                 Server. 
                 certificates 
               
               
                 SDS-SKRI 
                 AP-TA 
                 The SDS Secure Key Request Interface is used 
                 HTTPS/TLS 
               
               
                   
                   
                 for the transactional distribution of Key 
                 Mutual 
               
               
                   
                   
                 information between the Trusted Authority and 
                 authentication using 
               
               
                   
                   
                 the Authentication Proxy. 
                 TA signed 
               
               
                   
                   
                   
                 certificates 
               
               
                 SDS-IXI 
                 AP-PS 
                 The SDS Image Exchange Interface is used to 
                 Authentication and 
               
               
                   
                   
                 communicate SM Client download information 
                 encryption 
               
               
                   
                   
                 and exchange SM Client Images between the 
               
               
                   
                   
                 Authentication Proxy and Personalization 
               
               
                   
                   
                 Servers (i.e. CAS or TD). 
               
               
                 SDS-PRI 
                 AP-TA 
                 The SDS Purchase Report Interface is used to 
                 HTTPS/TLS 
               
               
                   
                   
                 forward SM Purchase Report information to 
                 Mutual 
               
               
                   
                   
                 the purchase arbitrator. 
                 authentication using 
               
               
                   
                   
                   
                 TA signed 
               
               
                   
                   
                   
                 certificates 
               
               
                 Operations 
                 AP-NMS 
                 The OSSI Interface used to provide SDS SM 
                 Unspecified - MSO 
               
               
                 Support 
                   
                 and Infrastructure monitoring information to 
                 dependent 
               
               
                 System 
                   
                 the MSO Network Management Systems and 
               
               
                 Interface 
                   
                 other Operations Support Systems (OSS). 
               
               
                 Provisioning 
                 AP-SPS 
                 The Provisioning Interface is used to carry SM 
                 Unspecified - MSO 
               
               
                 Interface 
                   
                 Host provisioning and configuration 
                 dependent 
               
               
                   
                   
                 information messages between the SDS 
               
               
                   
                   
                 Provisioning System and Authentication Proxy. 
               
               
                   
                   
                 The Provisioning Interface is included for 
               
               
                   
                   
                 completeness and will not be formally 
               
               
                   
                   
                 specified. 
               
               
                 Local 
                 AP-LKS, 
                 The Local Records Exchange Interface is used 
                 Unspecifie - MSO 
               
               
                 Records 
                 SPS-LKS 
                 to distribute Keys locally throughout the MSOs 
                 dependent 
               
               
                 Exchange 
                   
                 SDS infrastructure. 
                 (MSOs adopt the 
               
               
                 Interface 
                   
                 The Local Records Exchange Interface is 
                 same security 
               
               
                   
                   
                 included for completeness and will not be 
                 conventions defined 
               
               
                   
                   
                 formally specified. 
                 for other 
               
               
                   
                   
                   
                 infrastructure 
               
               
                   
                   
                   
                 interfaces)