Abstract:
Content access may be provided and processed by assigning responsibility for obtaining entitlement data to the client&#39;s browser. Thus, in one example, the client may be configured to synchronize and coordinate data lookups associated with a content request, rather than relying on the server to do so. The network architecture may use a mediator design pattern, in which the client&#39;s browser acts as the mediator (i.e., middleman) between a content server and an entitlement data server. Accordingly, synchronous calls between server-side services might not be required. Instead, data necessary for the content server to process a client request for access to protected content may be received in the incoming request from the client&#39;s browser.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of co-pending U.S. application Ser. No. 12/624,783 filed Nov. 24, 2009, entitled “METHOD FOR SCALABLE ACCESS CONTROL DECISIONS.” The contents of the above noted application are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    Aspects described herein relate generally to accessing digital content. More specifically, aspects of the present disclosure relate to processing a user&#39;s request to access protected digital content based on entitlement data. 
       BACKGROUND 
       [0003]    With significant technological advances made in the telecommunications industry over the last decade, communication companies have continually developed new and attractive ways to provide entertainment, information and communication services to customers in order to remain competitive in the market. For cable and other content service providers in particular, one such development has been the delivery of anytime, in-home access to digital content, commonly referred to as on-demand programming. Digital content or simply content may refer broadly to the information contained in a transmitted signal that provides value to an end-user/audience, and includes, for example, movies, television shows, news broadcasts, and other forms of media. With the advent of more sophisticated mobile telecommunication devices, viewing movies, television shows, news broadcasts, and other forms of media on-demand has become extremely popular. As a result, it has become increasingly burdensome to ensure that only users who are entitled to view certain protected digital content are able to gain access to such content. 
         [0004]    When a client (e.g., subscriber to a content service provider, customer, service purchaser, user, etc.) makes a request for a particular item of digital content, the server hosting such content must make an access control determination based on the client&#39;s entitlement data (e.g., the user&#39;s subscription plan) and the content&#39;s metadata (attributes about the specific content requested, for example the title of a program (e.g., an episode name), copyright year, actors or actresses in a movie or show, length, content provider and the like) before the server grants the client access to the requested content. Entitlement data may be piece or pieces of data about a subscriber that inform a determination of his or her rights to access certain content items or types of content. Content metadata may be a piece or pieces of data about a piece of content that inform a determination of a subscriber&#39;s rights to access that content. Currently, client entitlement data and content metadata lookups are usually performed at the time of the request by the content server. With increasing demand for content, a content server may be overloaded with requests and require additional resources to obtain entitlement data and/or content metadata for each content request. 
       BRIEF SUMMARY 
       [0005]    The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects herein that allow for rendering access control decisions when a client (e.g., client, customer, service purchaser, user, etc.) makes a request to access protected content. It is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. The following summary merely presents some concepts of the disclosure in a simplified form as a prelude to the more detailed description provided below. 
         [0006]    As described above, when a client makes a request for a particular item of digital content, the server hosting such content must ensure that the client is entitled to view the content before granting access to the content. To ensure that the client is entitled to view the content, the server must examine certain data associated with the client and with the content. To improve scalability in authorizing a client&#39;s request to access protected content, aspects described herein assign responsibility to the client&#39;s browser to synchronize and coordinate data lookups associated with the request, rather than relying on the server to do so. Thus, the client&#39;s browser/system acts as the mediator (e.g., middleman), thereby alleviating the need for synchronous calls between server-side services. Instead, data necessary for the server to process a client request for accessing protected content may arrive on the incoming request from the client&#39;s browser. Such data may include, for example, the user&#39;s identity (e.g., email address), the user&#39;s IP address, the programs and/or content that the user is subscribed to, the provider of the requested content and the like. As a result, server-side services may render access control decisions in response to client requests for access to protected content without needing to engage in any additional communications (e.g., beyond communications with the client). Relieving a server of such responsibility results, for example, in the server being capable of processing client requests in a rapid, scalable and efficient manner, which generally will allow servers to operate with lower memory requirements and with fewer dependencies on other central processing unit (CPU) resources. 
         [0007]    One or more aspects described herein relate to rendering an access control decision based on entitlement data that makes an assertion about a service subscriber&#39;s rights. For example, entitlement data may include identification of content items, type of content items, content item providers and the like to which the user is entitled access. Entitlement data may be passed to a content server along with the client&#39;s request for access to protected content available through the server. Entitlement data may further make an assertion related to the client&#39;s identity (e.g., email address), workstation IP address, and a timestamp used for expiration purposes. 
         [0008]    One or more aspects described herein relate to rendering an access control decision based on content metadata that makes an assertion about a particular piece of content. For example, content metadata may include identification of a content item, content provider, availability dates, and the like. Content metadata may be passed to a content server along with the client&#39;s request for access to protected content available through the server. Content metadata may further make an assertion related to cache management, such as a timestamp used for expiration purposes. 
         [0009]    According to another aspect, entitlement data and/or content metadata may be digitally signed to ensure its authenticity and its origin, and may also be encrypted to prevent unintended recipients from being able to view its contents. Digital signatures allow the recipient of information to verify the identity of the information sender, and also to verify that the information was not altered while in transit. 
         [0010]    To ensure that a client&#39;s request for protected content is authenticated and authorized, the client&#39;s browser may retrieve the client&#39;s entitlement data from the client device&#39;s cache each time the client makes a request for protected content from a content server. By assigning responsibility for providing entitlement data to the client&#39;s browser, the content server is relieved from having to perform entitlement data lookups. 
         [0011]    According to another aspect described herein, if the client&#39;s entitlement data is not cached in the client device, the client may retrieve the entitlement data from an entitlement data server. The entitlement data server may, in one or more arrangements, respond to the request with the entitlement data stored in a cookie. The cookie may be passed to the client&#39;s browser cache for further use. According to one or more aspects, the request for the entitlement data may comprise a redirect from the content server. The request and the redirect may be digitally signed by the content server so that the entitlement server is able to verify the source of the request. This prevents unauthorized devices from accessing entitlement data. To obtain the digitally signed redirect, the client may, in response to determining that the entitlement data is not locally cached, request a redirect from the content server. A token may be used to prove that the subscriber is entitled to receive the redirect. In one or more examples, this token may defend against cross-site request forgery (CSRF). 
         [0012]    According to another aspect, content metadata may be passed to a client along with any lists or listing of available content. The lists or listing of available content may be determined or generated based on entitlement data for a subscriber. When the subscriber makes a selection of a particular piece of content, the associated content metadata may then be passed along with the content request to a content server. By assigning responsibility to the client of managing the content metadata, the content server is relieved from having to retrieve the content metadata again before making an access control decision. 
         [0013]    The details of these and other embodiments of the present disclosure are set forth in the accompanying drawings and the description below. Other features and advantages of the disclosure will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements and in which: 
           [0015]      FIG. 1  illustrates an example network environment in which content items may be distributed to subscribing clients according to one or more aspects described herein. 
           [0016]      FIG. 2  illustrates a block diagram of a computing system that may be used according to one or more aspects described herein. 
           [0017]      FIG. 3  illustrates a data flow for requesting access to protected content according to one or more aspects of the present disclosure. 
           [0018]      FIG. 4A  is a flowchart illustrating an example framework underlying the method of transmitting entitlement data across domains. 
           [0019]      FIG. 4B  is a flowchart illustrating an example framework underlying the method of transmitting entitlement data across domains. 
           [0020]      FIG. 5  is a flowchart illustrating a method by which a client system may request and access content from a content server by providing entitlement data. 
           [0021]      FIG. 6  illustrates an example of content metadata according to one or more aspects described herein. 
           [0022]      FIG. 7  is a flowchart illustrating a method for processing content requests by a content server based on entitlement data. 
           [0023]      FIG. 8  is a flowchart illustrating a method by which an entitlement server may provide entitlement data to a client system so that the client system is able to retrieve protected content items. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    In the following description of the various embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration various embodiments in which one or more aspects of the disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present disclosure. 
         [0025]      FIG. 1  illustrates a content distribution system  100  that may be used in connection with one or more aspects described herein. The distribution system  100  may include a headend  102 , a plurality of browsers  106  (e.g., browsers  106   a - 106   n ) contained on and utilized by a corresponding plurality of client devices  108  (e.g., client devices  108   a - 108   n ), and a media distribution network  104 . The distribution system  100  may be used as a media service and content provider/client system wherein the provider (or vendor) generally operates the headend  102  and the network  104 , and the client (i.e., client, customer, service purchaser, user, etc.) generally provides the client device  108  and operates the browser  106  thereon. The client device  108  with corresponding browser  106  is generally located at the client&#39;s location such as a client&#39;s home, a hotel room, a business, etc. The client device  108  may include, for example, a personal computer, media player, etc. 
         [0026]    The headend  102  may include a plurality of devices  110  (e.g., devices  110   a - 110   n ) such as data servers, computers, processors, security encryption and decryption apparatuses or systems, and the like configured to provide content (e.g., movies, music, television programming, games, and the like), processing equipment (e.g., provider operated client account processing servers), service transceivers (e.g., transceivers for standard broadcast television and radio, digital television, HDTV, audio, MP3, text messaging, gaming, etc.), and the like. At least one of the devices  110  (e.g., a sender security device  110   x ), may include a security system. 
         [0027]    In one or more embodiments, network  104  may further provide access to a wide area network (WAN)  112  such as the Internet. The physical structures of network  104  may be of any type, such as coaxial cable network, fiber optic cable network, hybrid fiber (coax and fiber) cable network, telephone (land or cellular) network, satellite network, etc. 
         [0028]    Accordingly, browser  106  or headend  102  may have access to content and data on the wide area network. Content items may include audio, video, text and/or combinations thereof. In one example, a content and service provider may allow a client to access websites  114  and content provided by content providers  116  connected to the Internet (i.e., WAN  112 ) using the browser  106 . Websites  114  may include television show description sites, movie review sites, news webpages and the like. In another example, a service provider (e.g., a media provider) may supplement or customize media data sent to a client&#39;s browser  106  using data from the WAN  112 . 
         [0029]      FIG. 2  illustrates example components of a computing system, such as server  110   a  or client device  108   a.  A computing system may include a housing  200  for various internal components, and may also include various client input devices  205 , such as a keyboard, mouse, touch screen or touch pad input, etc. Additional output devices, such as an audio output device (such as speakers, headphones, etc.—not illustrated) may also be included. 
         [0030]    The example illustrated in  FIG. 2  is, of course, merely an example, and other configurations (e.g., having more or fewer components, duplicate/combined components, etc.) may be used for the computing system. Additionally, the configuration shown in  FIG. 2  may also be used to implement any of the other components described herein, with computer-executable instructions stored on memory (e.g., hard drive  210 , RAM  215 , etc.) that, when executed by a processor (e.g., processor  220 ), cause the component to perform as described herein. 
         [0031]    The computing system may include one or more processors  220 , which may be a microprocessor of programmable logic circuit configured to execute instructions to perform the various features described herein. Those instructions may be stored, for example, on an internal read-only memory (ROM)  225 , which may contain the built-in operating system (BIOS) for the computing system. The instructions may also be stored in other areas of memory as well, such as a hard drive  210 , removable media  230  (e.g., floppy disk, FLASH drive, CD-ROM, DVD-ROM, etc.), or even in random-access memory (RAM)  215 . Storage in hard drive  210  may be configured to store a variety of information such as application data, user preference information, content items, broadcast listings, media recording schedules, application programming and the like. 
         [0032]    The computing system may also include a communication interface  235 , which may include any desired type of hardware and/or software interface configured to communicate with other devices, e.g. over a network such as network  104 . For example, communication interface  235  may include any appropriate hard-wired (e.g., twisted pair, coaxial cable, fiber optic cable, hybrid fiber cable, etc.) or wireless (e.g., radio frequency, microwave, infrared, etc.) coupling and protocol (e.g., Home Plug, HomePNA, IEEE 802.11(a-b), Bluetooth, HomeRF, etc.) to meet the design criteria of a particular application and/or network. As another example, communication interface  235  may be a USB port. Communication interface  235 , in one or more arrangements, may include a network interface circuit, which may be used to communicate with any desired external network. Such a network interface circuit may include a local wireless network interface, such as for a WiMAX network, BLUETOOTH network, an ANSI 802.11x network, or any other local wireless network, and may include one or more wireless antennas. The network interface circuit may also support longer-range wireless networking, such as cellular telephone wireless networks, satellite, etc. Communication interface  235  and network interface circuit thereof need not be limited to wireless networks, and may alternatively include support for wired networks as well, such as Ethernet, cable television, etc. 
         [0033]    The computing system may also include a video processor  255 , which may be any desired type of processor or circuit that supplies a client device, such as client device  108   a,  with images to show a user. For example, a video processor  255  may be a video graphics card. The video processor  255  may include any desired type of hardware and/or software configuration to receive, decode and display video data received from a network (which may be processed by other devices, such as a communication interface  235  and/or a processor  220  first. 
         [0034]    The computing system may also include a secure video processor  250  and secure memory  245 . Data received and/or processed by secure video processor  250  may be stored in secure memory  245 . The secure video processor  250  may include additional hardware and/or software to handle the reception, decrypting, decoding and/or display of video data that has been secured in a particular manner. For example, some incoming streams of video data (e.g., a stream of a movie available only under a certain subscription plan) may be encrypted, and the secure video processor  250  may be configured to handle the decryption of that incoming data stream. Such incoming encrypted data streams may be decrypted within secure video processor  250 , and the resulting decrypted stream may be supplied to the video processor  255  for output on, for example, client device  108   a.    
         [0035]      FIG. 3  illustrates a data flow for requesting access to protected content. The protected content may be content (e.g., audio, video, text and/or combinations thereof) on a server that might only be accessed by an authorized and authenticated subscriber or client. As illustrated, a client at client system  300  may wish to access protected content located on content server  303  through browser  301  operating on client system  300 . The client may seek access to the protected content on content server  303  over a network such as the Internet. From content server  303 , the client may receive programs executable by browser  301 , such as Java Applets, JavaScript, and Flash. For example, the client may receive an applet  304 , which generally refers to an application that performs a specific task, such as installing a plug-in within the context of a larger program, and may be used to provide interactive features to web applications that other languages or protocols, such as HTML, are unable to provide. As described above, applet  304  may be, for example, a Java Applet that can be embedded in a web page of a site hosted by content server  303 . In one example, applet  304  installs plug-in  305  to perform client-side processes on behalf of content server  303 . Plug-in  305  may be, for example, software that is added to browser  301  in order to enhance the browser&#39;s capability, e.g., to process entitlement information and/or to enable browser  301  to support different types of digital content (video, audio, etc.). Additionally, browser  301  may include cache  306 , in which a client&#39;s entitlement data is stored. 
         [0036]    Furthermore, content server  303  may retrieve content metadata from a content metadata server (e.g., server  310 ) to determine certain attributes of a content item or items. Thus, in one example, in response to a client request to the content server to determine available content, content server  303  may retrieve content metadata from content metadata server  310  and embed it in the response to the client. In one or more arrangements, content metadata server  310  may comprise a database within server  303 . Additionally or alternatively, content metadata may be cached in the content server  303 . 
         [0037]    A user of client system  300  that requests access to protected content on content server  303  provides entitlement data and the appropriate content metadata (e.g., metadata corresponding to the requested protected content) along with the request for the protected content. Entitlement data may be cached in client system  300  and may include, for example, identification information of a user or subscriber of client system  300  (e.g., email address, name, subscriber identification number), the IP address of client system  300 , the user&#39;s subscription entitlements, a timestamp for expiration, and/or a digital signature by entitlement server  307  from which the entitlement data was passed. Content metadata is available from the client&#39;s previous request context and may include, for example, content identification number, content provider, availability dates, a timestamp for expiration, a digital signature by the content server  303  through which the previous request context was delivered, and/or a digital signature by the content metadata server  310  from which the content metadata was retrieved. 
         [0038]    In some instances, entitlement data might not exist in cache  306  of client system  300 . Therefore, client system  300  may need to request entitlement data from entitlement server  307 , which may be in a different domain than content server  303 . When client system  300  makes a request for protected content from content server  303 , without having entitlement data stored in cache  306  of client system  300 , client  300  may be redirected by content server  303  to request entitlement data from entitlement server  307 . As described in further detail below, the redirect may be digitally signed to verify authenticity. If entitlement server  307  accepts the redirect request from content server  303 , and finds the entitlement data requested by client system  300 , entitlement server  307  may then issue a redirect to content server  303  with the entitlement data. If content server  303  accepts the redirect from entitlement server  307 , content server  303  may then return the entitlement data to the client system  300 , which may then make a request for content to content server  303 , including the entitlement data and/or content metadata in the request. The content server  303  may then determine if the client  300  is authorized to receive the requested content item and if so, provide client  300  with access to the content. Alternatively or additionally, if content server  303  and entitlement server  307  are in the same domain, client  300  may request entitlement data from server  307  without requesting a redirect from content server  303 . 
         [0039]      FIGS. 4A and 4B  are flowcharts that illustrate example frameworks underlying the method of transmitting entitlement data across domains. Transmitting entitlement data from one domain to another generally requires establishing a trust relationship between the domains. One example of how a trust relationship may be established between domains is through symmetric-key cryptography. The process of encrypting and decrypting data through symmetric-key cryptography is illustrated in  FIG. 4A . At step  420 , data that is to be sent exists in plaintext or cleartext, which means, for example, the data has not been encrypted and is readable without additional processing of the information. For example, plaintext data may be a list of subscription services to which a client is entitled to access. At step  421 , the data in plaintext is encrypted before it is sent. Encryption involves executing a mathematical function on plaintext data, in combination with a secret key, to disguise the data in such a way as to hide its actual substance. Encryption is used to make sure that information remains hidden from unintended recipients, even those who are able to view the encrypted data. For example, a list of client entitlements may be encrypted by substituting different information, according to a particular secret key (e.g., word, number, phrase), for the information that is actually contained in the list of entitlements. At step  422 , the encrypted data, which is known as ciphertext, is sent to a recipient. At step  423 , the data in ciphertext undergoes decryption, which is the process of reverting ciphertext to its original plaintext format, through use of the same substitution pattern and secret key, in a manner that allows only the intended recipient to read the information. For example, the information originally contained in the aforementioned list of client entitlements replaces the unreadable information that had previously been substituted. At step  424 , the data is read in plaintext by the intended recipient. 
         [0040]    Transmitting entitlement data from one domain to another may also be accomplished by establishing a trust relationship between the domains through asymmetric (public key) cryptography. The process of encrypting and decrypting data through asymmetric (public key) cryptography is illustrated in  FIG. 4B . Asymmetric cryptography uses a pair of algorithm keys to encrypt and decrypt data such that it may be transmitted securely with only the intended recipient being able to view the data. In one or more arrangements, encryption may include PGP encryption. At step  430 , data that is to be sent exists in plaintext or cleartext, and the intended recipient already possesses a public and private key pair, the public key being maintained by a public administrator. At step  431 , the data in plaintext is encrypted by the sender before it is sent by using the intended recipient&#39;s public key that the sender may obtain, for example, from the public administrator. In step  432 , the encrypted data, which again exists as ciphertext, is transmitted to the intended recipient. At step  433 , when the recipient receives the ciphertext data, the recipient may decrypt the data with the private key that only the recipient has access to. Then at step  434 , the recipient is able to view the data in plaintext, as it was originally sent. 
         [0041]      FIG. 5  illustrates a method by which a client system may request and access content from a content server by providing entitlement data. In step  500 , the client system may request access to a content server. For example, the client system may receive, through a browser application, a network address corresponding to a content server site. The browser application may be, for example, a web browser such as MICROSOFT INTERNET EXPLORER, MOZILLA FIREFOX and the like. In step  505 , the client may receive content server data in response to the request. The content server data may include a website, a listing of content available on the content server, content item metadata, web applications (e.g., applets) and/or combinations thereof. In one or more arrangements, content metadata may be unique to the requesting client system. As further explained herein with reference to  FIG. 6 , content metadata may be used to annotate each video in a listing of videos provided to the client system in response to a request for access to the content server. For example, the content metadata may identify that a particular item of video content is provided by a particular content provider. In one or more arrangements, the web applications may comprise Java Applets. The application through which the content server data was requested may be configured to render and/or execute the data received in response to the request. 
         [0042]      FIG. 6  illustrates an example of content metadata that may be embedded in the content server data received by the client system from the content server in step  505 . Digital signature (i.e., sig) parameter  601  of content metadata  600  represents a digital signature by the content server (e.g., content server  303  of  FIG. 3 ). The digital signature verifies to other entities, domains or servers that a request or data transmitted is authorized by the signing entity. For example, including digital signature  601  with a content request ensures that when the content server receives the request, the content server is able to authenticate the request. Release_URL parameter  605  may comprise an encrypted version of a true address for a content item. A true address may be a location at which a content item is stored and accessible. In some arrangements, a client browser may initially have knowledge of and access a pseudo-address for a content item. The pseudo-address is generally not where the content item is stored. Instead, the pseudo-address references a location where authentication processes are invoked to verify the requesting client or user prior to revealing the content item&#39;s true address (i.e., Release_URL  605 ) and allowing the client browser to access the content item. The requested content item, on the other hand, may be identified in content id (i.e., video_id) parameter  603 . Content id parameter  603  may include, for instance, an identifier assigned to the content item by the content server. 
         [0043]    Provider parameter  610  may be passed in cleartext to the client (and over the network), so that a determination may be made as to whether the client is entitled to view the content. For example, if provider parameter  610  corresponds to “HBO,” a client system may determine whether the user has subscribed to HBO using the entitlement data. If not, the request for the HBO content may be denied or the content may not be offered to the client system in the first place, and thus a request for such content is not made. Further, expiration time parameter (i.e., exp)  615  may be used to indicate a time that digital signature  601  will expire or become invalid. Upon expiration of digital signature  601 , the signature might not be recognized by a content server or entitlement data server as a valid signature. Expiration parameter time  615  may be expressed in terms of second, minutes, hours, days, weeks, months and the like. 
         [0044]    With further reference to  FIG. 5 , in step  510 , the client system or an applet executing thereon may determine whether entitlement data relevant to the content items available through the content server is cached in the client system. The entitlement data may include information regarding the subscriptions and/or rights the client has with respect to content items available on the content server. 
         [0045]    If entitlement data is not cached at the client, the client may determine if a content server token is cached in step  520 . A content server token generally refers to a key or identifier that is issued by the content server as a way to verify that transmitted data and/or requests are authorized by the content server. In one or more arrangements, the token may comprise a CSRF token (i.e., a token used to defend against CSRF). If a content server token is not cached, the client may select a random token in step  525 . Additionally, the client may notify the content server of the token selected. 
         [0046]    Once the token is retrieved and/or set, the client may request, from the content server, a digitally signed redirect for requesting entitlement data from an entitlement server in step  530 . The request for the digitally signed redirect may be appended with or include the token. The token allows the content server to verify that the request is received from and the redirect is being provided to an authorized source. Similarly, the request for entitlement data may be required to be digitally signed by the content server so that the entitlement data server does not distribute entitlement data to unverified or unauthorized entities (e.g., hackers). The content server and the entitlement data server may also be on the same domain, in which case the aforementioned redirect might not be required. For example, if the content server and entitlement data server are on the same domain, the client may make a request for entitlement data directly to the entitlement data server, rather than the client&#39;s request reaching the entitlement data server through a redirect issued by the content server. 
         [0047]    In step  535 , the client may receive and follow the digitally signed redirect received from the content server. The redirect is configured to direct the client browser or applet to an entitlement data server storing entitlement data for the client. The redirect may further include a request for the entitlement data. Accordingly, instead of retrieving the entitlement data from the entitlement data server, the content server uses the client as an intermediary or mediator so that the content server does not need to communicate with the entitlement data server. In response to the request for the entitlement data included in the digitally signed redirect, the client may receive and follow another redirect in step  540 . This subsequent redirect may be directed back to the content server for requesting the content item. For example, the redirect to the content server may include a request for the content item including the entitlement data. Additionally, the client may cache the received entitlement data in step  545 . 
         [0048]    If entitlement data is cached at the client system or once the entitlement data has been retrieved from an entitlement data server, the client may optionally receive a list of content items that the user is entitled to access in step  550 . The list may be generated by the client by comparing the entitlement data with content metadata of content items available at the content server. Alternatively or additionally, the list may be generated by the server based on the entitlement data and provided to the client system. In step  555 , the client may subsequently receive a user selection of a content item. The client may then transmit a request for the selected content item to the content server in step  560 . The request may include the entitlement data and content metadata to prove that the client has a right to access the content item. In one or more arrangements, a request for content may include the pressing of a play button displayed alongside or within a content item. Once the request for the content item has been sent to the content server with the entitlement data and content metadata, the client may receive an address or location information for the content item in step  565 . In one arrangement, the address may correspond to an unencrypted version of an address specified in the content item request script. In step  570 , the client may use the address to access, retrieve (e.g., download/stream) and render the content item from the content server. 
         [0049]      FIG. 7  illustrates a method for processing content requests by a content server based on entitlement data. In step  700 , for example, the content server may receive a request for access to the content server from a client device or system. The request may include login credentials if the user is required to login to access information provided on the content server (e.g., videos, text, audio and other content items). In one or more arrangements, login credentials might not be needed. In step  705 , the content server may transmit content server data to the client in response to the request. The content server data may include a cookie that stores server-specific information such as an identifier (e.g., URL), a content server specific token, user information and the like. The content server data may further include a webpage, applets, audio, video, text, content metadata and the like. In one example, the content server may provide an applet or other executable content (e.g. scripts, Flash applications, and the like) for execution on the client system. The applet may act as an interface between the client system and the content server. Thus, data requests (e.g., content and entitlement data) and content received from the content server may be processed through the applet. In another example, the content server may retrieve content metadata for content items available therethrough from a content metadata server or a local database. 
         [0050]    In step  710 , the content server may determine if an entitlement data redirect request has been received. As noted herein, clients may be required to request an entitlement data redirect if the client does not have the entitlement data cached and so that entitlement data is only provided to authorized requestors. By requesting the redirect from the content server, a client may prove that it is an authorized requestor. If an entitlement data redirect request is received, the content server may verify that a token appended to the request is valid in step  715 . For example, the content server may determine whether the token matches the content server specific token that is issued by the content server to authorized clients/subscribers upon accessing the server. Alternatively, the token may be client generated, in which case the content server may verify that the token appended to the request matches a client generated token of which it was previously notified. Once the token and request has been verified, the content server may provide the client with a digitally signed redirect to an entitlement data server in  720 . The redirect may correspond to a request for entitlement data form the entitlement data server and may include a signature or key that is unique to the content server. Accordingly, a request or other data may be signed with the signature or key to prove that the request originated or is authorized by the content server. 
         [0051]    In step  725 , the content server may receive a content request including content metadata. The content request may comprise a redirect from the entitlement data server or may be a request originating (i.e., non-redirect) from the client if the client has entitlement data already cached. In step  730 , the content server may verify that the entitlement data and content metadata are not expired. That is, in some arrangements, entitlement data may expire so that changes to the user&#39;s entitlement are accurately and timely reflected in the entitlement data; similarly content metadata may expire so that changes to the content&#39;s attributes are accurately and timely reflected in the content metadata. The expiration may be stored in the entitlement data and/or content metadata as a specific expiration time or date or as a length of time in addition to a start time or date. 
         [0052]    If the entitlement data and content metadata have not expired, the content server may subsequently compare the entitlement data and content metadata to determine if the requesting subscriber is entitled to access the requested content item in step  735 . For example, if the content metadata specifies that the provider of the content was a particular provider such as HBO or SHOWTIME, the content server may determine if the entitlement data specifies that the user has a subscription to that content. Alternatively or additionally, the entitlement data may specify a type of content that the user is entitled to access such as comedies, sitcoms, dramas, television shows, movies and the like. In yet another example, entitlement data may specify that the user has access to content of a certain quality (e.g., high definition, high resolution, standard definition) or of a certain length (e.g., all videos under 5 minutes long). Other types of entitlement specifications may be used as well. The content server may further determine whether the user information included in the entitlement data matches the user or subscriber information in a content server cookie cached in the subscriber&#39;s browser. A subscriber&#39;s login information may be stored in a cookie upon login. 
         [0053]    If the entitlement data is valid for the requesting subscriber and is effective for the requested content item (i.e., provides access for the requested content item), the content server may transmit an unencrypted address for the content item to the subscriber in step  740 . In one example, the subscriber&#39;s content request (e.g., content metadata  600  of  FIG. 6 ) may include an encrypted address  605  ( FIG. 6 ) of the content item. Accordingly, the content server may decrypt this address and reveal it to the subscriber&#39;s applet or browser. In step  745 , the content server may provide the requested content item to the subscriber, e.g., in response to the client&#39;s browser or applet accessing the unencrypted address. 
         [0054]      FIG. 8  illustrates a method by which an entitlement server may provide entitlement data to a client system so that the client system is able to retrieve protected content items. In step  800 , the entitlement server may receive a request for entitlement data from the client system. Recall from  FIG. 7 , for example, that this request from the client system may be in the form of a digitally signed redirect provided to the client system by the content server. In step  805 , the entitlement server may check that the request is digitally signed by the content server. For example, checking that the request is digitally signed by the content server ensures that the request was authorized by the content server, thus also ensuring the entitlement data server does not distribute entitlement data to unverified or unauthorized entities. The digital signature may comprise a series of bits, characters and/or numbers appended or otherwise included in the request redirect string. If the request is not digitally signed by the content server, then in step  810  the entitlement server rejects the request for entitlement data and the routine may end. 
         [0055]    If, in step  805 , it is determined that the request is digitally signed by the content server, then the entitlement server may verify the parameters of the request in step  815 . For example, the entitlement server may examine the expiration parameter of the request to ensure that the digital signature has not expired, and is thus a valid signature. There can be any number of parameters of the incoming request that the entitlement server verifies in addition to, or instead of, the expiration parameter. Further, the parameters may be examined in any number of alternative ways by the entitlement server. If the entitlement server verifies the parameters of the incoming request, then in step  820 , the entitlement server may attempt to retrieve the requested entitlement data. For example, the entitlement server may read a login cookie stored on the client system and extract a user&#39;s identity. A login cookie may contain, for example, login information that was submitted by a user to a content provider upon logging into a site corresponding to the content provider. After extracting the user&#39;s identity information, an entitlement server web application may then determine if a database has entitlement data for the user based on the user&#39;s identity information. The entitlement server may also attempt to retrieve entitlement data in alternative ways in addition to those described above. 
         [0056]    If entitlement data is found by the entitlement server in step  825 , then in step  830  the entitlement server may issue a digitally signed redirect to the content server for the client to follow. The digitally signed redirect may pass to the content server the entitlement data found by the entitlement server. The entitlement data may, in one or more examples, be passed as a cookie through the client&#39;s browser. Including a digital signature with the entitlement data in step  830  ensures that when the content server receives the entitlement data, the content server is able to authenticate that the data came from the entitlement server. The entitlement data passed from the entitlement server to the content server in the digitally signed redirect may include all or part of the entitlement data that was requested by the client system in step  800 . For example, if a client&#39;s subscription plan is being processed or is otherwise unavailable, in whole or in part, then data associated with the client&#39;s plan might not be included in the entitlement data passed to the content server, even if such data was included in the request from the client system. In some arrangements, only entitlement data relevant to the requested content item may be provided in the redirect. 
         [0057]    If no entitlement data is found at step  825 , then the entitlement server may send to the client system a notification that no entitlement data was found at step  835 . For example, JavaScript running on the entitlement server may execute script for generating a pop-up notification on the browser of the client system, informing the client system that no entitlement data was found in response to the request. Optionally, at step  840 , the entitlement server may further issue a redirect to the content server without entitlement data. 
         [0058]    The methods and features recited herein may further be implemented through any number of computer readable media that are able to store computer readable instructions. Examples of computer readable media that may be used include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, DVD or other optical disk storage, magnetic cassettes, magnetic tape, magnetic storage and the like. 
         [0059]    Additionally or alternatively, in at least some embodiments, the methods and features recited herein may be implemented through one or more integrated circuits (ICs). An integrated circuit may, for example, be a microprocessor that accesses programming instructions or other data stored in a read only memory (ROM). In some such embodiments, the ROM stores programming instructions that cause the IC to perform operations according to one or more of the methods described herein. In at least some other embodiments, one or more the methods described herein are hardwired into an IC. In other words, the IC is in such cases an application specific integrated circuit (ASIC) having gates and other logic dedicated to the calculations and other operations described herein. In still other embodiments, the IC may perform some operations based on execution of programming instructions read from ROM or RAM, with other operations hardwired into gates and other logic of IC. Further, the IC may output image data to a display buffer. 
         [0060]    Although specific examples of carrying out the aspects of the disclosure have been described, those skilled in the art will appreciate that there are numerous variations and permutations of the above-described systems and methods that are contained within the spirit and scope of the disclosure as set forth in the appended claims. Additionally, numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.