Abstract:
Methods and systems provide secure functions for a mobile client. A circuit may include a memory configured to store a server access key and a first function authentication key. The circuit may also include authentication circuitry configured to access the server access key to authenticate access to a server to download a function capsule comprising a first function and to access the first function authentication key to authenticate use of the first function of the function capsule.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/894,024, which is a continuation of U.S. patent application Ser. No. 13/097,400 filed Apr. 29, 2011 (now U.S. Pat. No. 8,464,052), which is a continuation of U.S. patent application Ser. No. 12/632,354 filed Dec. 7, 2009 (now U.S. Pat. No. 7,937,585), which is a continuation of U.S. patent application Ser. No. 11/216,271 filed Aug. 30, 2005 (now U.S. Pat. No. 7,644,272), which claims priority to and the benefit of U.S. Provisional Application Ser. No. 60/621,288, filed Oct. 22, 2004, each of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The invention relates generally to the field of data communications and, more particularly, to systems and methods for providing secure functions on mobile terminals using smartcards, such as subscriber identity module (SIM) cards. 
     BACKGROUND 
     Currently, cables and wires are predominately used in communication networks for transferring information such as voice, video, data, etc. from one device to another. Devices on a communication network can generally be categorized as two types: servers and clients. Those devices that provide services/functions to other devices are servers; the devices that connect to and utilize the provided services/functions are clients. Generally in a wired network, authentication of a user for accessing a wired network, such as a local area network (LAN), can require the user to sign-on by providing information such as a login identification and a password on a client. And because each client within the wired network is physically connected to the network and can have a unique address, a communication session between a server on the wired network and the client is generally secure. 
     However, there is a growing desire to have network clients be portable or to have a mobile client that can operate beyond a defined environment. In contrast to wired clients, wireless or mobile clients can establish a communication session with a server without being physically connected to cables or wires. Accordingly, information such as voice, video, and data are transmitted and received wirelessly from one device to another and the information can be intercepted or tampered with by an impersonator posing as an intended user. Therefore, one way to ensure security within a mobile communication network would be to provide a system and method that can authenticate and identify the intended user to the mobile communication network supplying the services/functions. 
     In addition, as the development of mobile communication network technology continues to advance, various functions that can be downloaded through the mobile communication network to a mobile client have also advanced. These advanced functions (e.g., a call waiting function, a caller identification function, a music playing function, etc.) may require a higher level of security. Thus, there is also a need to provide additional security or securities for these advance functions to an intended user that goes beyond authenticating the intended user to the mobile communication network that is supplying the functions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages of the present invention will be more fully understood when considered with respect to the following detailed description, appended examples and accompanying drawings, wherein: 
         FIG. 1  is a schematic diagram of a mobile communication network architecture pursuant to aspects of the invention; 
         FIG. 2  is a more detailed schematic diagram of a mobile client of  FIG. 1 ; 
         FIG. 3  is a more detailed schematic diagram of a switching center of  FIG. 1 ; 
         FIG. 4  is a schematic diagram of another mobile communication network architecture pursuant to aspects of the invention; 
         FIG. 5  is a more detailed schematic diagram of a mobile client of  FIG. 4 ; 
         FIG. 6  is a detailed schematic diagram of a first embodiment of a function capsule of  FIG. 5 ; 
         FIG. 7  is a detailed schematic diagram of a second embodiment of a function capsule of  FIG. 5 ; 
         FIG. 8  is a detailed schematic diagram of a third embodiment of a function capsule of  FIG. 5 ; 
         FIG. 9  is a detailed schematic diagram of an embodiment of a plurality of function capsules of  FIG. 5 ; 
         FIG. 10  is a schematic diagram of yet another mobile communication network architecture pursuant to aspects of the invention; 
         FIG. 11  is a schematic diagram of a system and method for providing keys to a subscriber identity module (SIM) card pursuant to aspects of the invention; 
         FIG. 12  is a flowchart representative of one embodiment of operations pursuant to aspects of the invention; 
         FIG. 13  is a schematic diagram of an embodiment of a key management system that incorporates stateless key management modules (or stateless modules) pursuant to aspects of the invention; and 
         FIG. 14  is a schematic diagram of a key transfer embodiment between a stateless module and a smartcard pursuant to aspects of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The invention is described below, with reference to detailed illustrative embodiments. It will be apparent that the invention can be embodied in a wide variety of forms, some of which may be quite different from those of the disclosed embodiments. Consequently, the specific structural and functional details disclosed herein are merely representative and do not limit the scope of the invention. 
       FIG. 1  is a block diagram of a mobile communication network architecture that uses a smartcard for authentication and/or encryption. Exemplary embodiments of the present invention can be applied to the network architecture of  FIG. 1 , as well as other suitable architectures. 
     The network architecture of  FIG. 1  includes mobile network  10  that facilitates communications between one or more mobile clients, such as mobile client  12 , and one or more servers  14  (e.g.,  14   a ,  14   b , and/or  14   c ). Mobile network  10  may be a wireless communications system that supports the Global System for Mobile Communications (GSM) protocol. However, other multi-access wireless communications protocol, such as General Packet Radio Services (GPRS), High Data Rate (HDR), Wideband Code Division Multiple Access (WCDMA) and/or Enhanced Data Rates for GSM Evolution (EDGE), may also be supported. Mobile client  12  may be any device that is adapted for wireless communications with mobile network  10 , such as a cellular telephone, pager, personal digital assistant (PDA), vehicle navigation system, and/or portable computer. 
     Mobile network  10  includes one or more base stations  16  (e.g.,  16   a ,  16   b , and/or  16   c ) and switching center  18 . Mobile network  10  connects mobile client  12  to servers  14   a ,  14   b , and/or  14   c  either directly (not shown) and/or through second network  20 , such as a Public Switched Telephone Network (PSTN), an Integrated Services Digital Network (ISDN), a Packet Switched Public Data Network (PSPDN), a Circuit Switched Public Data Network (CSPDN), a local area network (LAN), the Internet, etc. Mobile network  10  is operated by a carrier that has an established relationship with an intended user (or subscriber) of mobile client  12  to use the wireless services provided through mobile network  10 . 
     Referring now to  FIG. 2 , mobile client  12  includes mobile terminal  122  (e.g., a mobile equipment or a phone) and smartcard  124 . More specifically, smartcard  124  of  FIG. 2  is a Subscriber Identity Module (SIM). SIM (or SIM card)  124  contains encryption key  126   a  that encrypts voice and data transmissions to and from mobile network  10  and authentication key  126   b  that specifies an intended user so that the intended user can be identified and authenticated to mobile network  10  supplying the mobile services. SIM  124  can be moved from one mobile terminal  122  to another terminal (not shown) and/or different SIMs can be inserted into any terminal, such as a GSM compliant terminal (e.g., a GSM phone). 
     To provide additional security, mobile terminal  122  may include an International Mobile Equipment Identity (IMEI) that uniquely identifies mobile terminal  122  to network  10 . SIM card  124  may be further protected against unauthorized use by a password or personal identity number. 
     Referring now back to  FIG. 1 , each base station  16   a ,  16   b ,  16   c  includes a radio transceiver that defines a cell and handles the radio-link protocols with mobile client  12 . A base station controller (not shown) may also be coupled between one or more base stations  16   a ,  16   b ,  16   c  and switching center  18  to manage the radio resources for one or more base stations  16   a ,  16   b ,  16   c . The base station controller may handle radio-channel setup, frequency hopping, and handovers (e.g., as the mobile client moves from one base station coverage area or cell to another). 
     The central component of mobile network  10  is switching center  18 . Switching center  18  acts like a normal switching node, such as a switching node in a PSTN or ISDN, and additionally provides all the functionality needed to handle an intended mobile user (subscriber), such as registration, authentication, location updating, handovers, and call routing to a roaming subscriber. In  FIG. 1 , it is switching center  18  that provides the connection of mobile client  12  to second network  20  (such as the LAN, the PSTN, the ISDN etc). 
     Referring now to  FIG. 3 , switching center  18  includes equipment identity register  182  and authentication register  184 . Identity register  182  includes a database that contains a list of all valid mobile terminals (e.g.,  122  of  FIG. 2 ) on network  10 , where each mobile client (e.g.,  12 ) is identified by its International Mobile Equipment Identity (IMEI). An IMEI is marked as invalid if it has been reported stolen or is not type approved. Authentication register  184  is a protected database that stores copies  126   a ′,  126   b ′ of the secret keys (e.g.,  126   a ,  126   b ) stored in each intended user&#39;s (or subscriber&#39;s) SIM card (e.g.,  124 ), which are used for authentication of an intended user and encryption/decryption of data transmitted over a radio channel of mobile network  10 . 
     Specifically, referring now also to  FIGS. 1 and 2 , mobile network  10  can be a GSM compliant network that authenticates the identity of an intended user through the use of a challenge-response mechanism. A 128-bit random number is sent to mobile client  12  from mobile network  10 . Mobile client  12  computes a 32-bit signed response based on the random number sent to mobile client  12  with an authentication algorithm using individual subscriber authentication key  126   b . Upon receiving the signed response from mobile client  12 , mobile network  10  repeats the calculation to verify the identity of the user. Note that individual subscriber authentication key  126   b  is not transmitted over the radio channel. It should only be present in SIM card  124 , as well as authentication register  184 . If the signed response received by network  10  agrees with the calculated value, mobile client  12  has been successfully authenticated and may continue. If the values do not match, the connection to network  10  is terminated. 
     In addition, SIM card  124  of  FIGS. 1 ,  2 , and  3  contains encryption key  126   a . Encryption key  126   a  is used to encrypt and decrypt the data transmitted between mobile client  12  and mobile network  10 . The encryption of the voice and data communications between mobile client  12  and network  10  is accomplished through use of an encryption algorithm. An encrypted communication is initiated by an encryption request command from mobile network  10 . Upon receipt of this command, mobile client  12  begins encryption and decryption of data using the encryption algorithm and encryption key  126   a.    
     As envisioned, an embodiment of the present invention provides additional security and/or securities to functions downloaded from a mobile communication network to a mobile client using a SIM card that goes beyond authenticating an intended user to the mobile communication network and encrypting/decrypting data to and from the network. 
     Referring to  FIG. 4 , a mobile communication network architecture pursuant to the present invention includes mobile network  410  that facilitates communications between one or more mobile clients, such as mobile client  412 , and one or more servers  414   a ,  414   b ,  414   c . Mobile network  410  may be a wireless communications network similar to the mobile network of  FIG. 1 , as well as other suitable networks. 
     In particular, mobile network  410  of  FIG. 4  includes copies  426   a ′,  426   b ′ of secret keys  426   a ,  426   b  stored in SIM card  424 . Keys  426   a ,  426   b ,  426   a ′,  426   b ′ are used for authenticating the intended user of SIM card  424  to mobile network  410  and encryption/decryption of data transmitted between mobile network  410  and mobile client  412  via communication link  510 . Copies  426   a ′,  426   b ′ of the secret keys may be stored in an authentication register (e.g., register  184  of  FIG. 3 ) and be managed by a switching center (e.g., switching center  18 ). In addition, to provide an additional security, SIM (or SIM card)  424  contains second authentication key  426   c  for authenticating the intended user to one or more function capsules  418   a ,  418   b ,  418   c  on mobile client  412 . 
     In one embodiment, a function capsule on mobile client  412 , such as function capsule  418   a , includes a call waiting function of mobile client  412 . Function capsule  418   a  and/or another capsule  418   b ,  418   c  may also include a caller identification (ID) function of mobile client  412 , an e-mailing function of mobile client  412 , a function for providing a highly sensitive financial service to mobile client  412 , a payment function of mobile client  412 , a product/service ordering function of mobile client  412 , a music function of mobile client  412  (e.g., compressing, depressing, and/or playing functions), etc. 
     Also, as is shown in  FIG. 4 , server  414   a  includes (or is coupled to) copies  418   a ′,  418   b ′,  418   c ′ of function capsules  418   a ,  418   b ,  418   c . These copies  418   a ′,  418   b ′,  418   c ′ may be downloaded to mobile client  412  as capsules  418   a ,  418   b ,  418   c  on mobile client  412 . In one embodiment, capsules  418   a ,  418   b ,  418   c  of mobile client  412  are downloaded from server  414   a  via mobile network  410  after the intended user has been authenticated to mobile network  410  using secret keys  426   a ,  426   b  on SIM card  424 . 
     Referring now to  FIGS. 4 and 5 , mobile client  412  includes mobile terminal  422  (e.g., a phone, a PDA, etc.) and Subscriber Identity Module (SIM)  424 . SIM (or SIM card)  424  contains encryption key  426   a  that encrypts voice and data transmissions to and from mobile network  410  and authentication key  426   b  that specifies an intended user so that the intended user can be identified and authenticated to mobile network  410 . In addition, SIM  424  includes one or more additional keys (e.g.,  426   c ,  426   d , etc.) to authenticate the intended user to one or more function capsules  418   a ,  418   b ,  418   c  stored in mobile terminal  422 . 
     Specifically and referring now to  FIGS. 5 and 6 , a function capsule on mobile terminal  422 , such as function capsule  418   a , includes an authentication module  555 . Authentication module  555  is a capsule facility that can be downloaded to mobile client  412  and be used for ensuring legitimacy of a user and/or for associating the legitimate (or intended) user to its desired function  515  on the function capsule. 
     In particular, authentication module  555  includes (or is coupled to) function authentication register  584 . Function authentication register  584  is a storage facility of authentication module  555  that stores copies  426   c ′,  426   d ′ of secret keys  426   c ,  426   d  of SIM card  424 . Using copies  426   c ,  426   d  of the secret keys, authentication module  555  can authenticate the intended user to function  515  stored in the function capsule. In one embodiment, key  426   c ′ is used for accessing (and/or decrypting) the function capsule and key  426   d ′ is used for authenticating the intended user to function  515  of the function capsule so that the user can utilize function  515 . 
     Referring now to  FIGS. 5 and 7 , a function capsule in another embodiment of the present invention includes first function  615   a , second function  615   b , and authentication module  655 . In this embodiment, authentication module  655  includes copies  426   c ′,  426   d ′ of secret keys  426   c ,  426   d  stored in SIM card  424 . In addition, authentication module  655  includes copy  426   e ′ of secret key  426   e  of SIM card  424 . Using these three secret keys  426   c ′,  426   d ′,  426   e ′, authentication module  655  can authenticate the intended user to a particular function from the plurality of functions  615   a ,  615   b  stored in the function capsule. In particular, key  426   c ′ may be used for authenticating the intended user to the function capsule, key  426   d ′ may be used for authenticating the intended user to utilize function  615   a , and key  426   e ′ may be used for authenticating the intended user to utilize function  615   b.    
     Referring now to  FIGS. 5 and 8 , a function capsule in yet another embodiment of the present invention includes first function  715   a , second function  715   b , and authentication module  755 . Like authentication module  655  of  FIG. 7 , authentication module  755  also includes copies  426   c ′,  426   d ′,  426   e ′ of secret keys  426   c ,  426   d ,  426   e  stored in SIM card  424 . However, unlike the embodiment of  FIG. 7 , here a first key (e.g., key  426   d ′) must first be used for authenticating the intended user to utilize first function  715   a  before a second key (e.g., key  426   e ′) can be used for authenticating the intended user to utilize second function  715   b.    
     Referring now to  FIGS. 5 and 9 , a further embodiment of the present invention includes function capsule  818   b  within function capsule  818   a . Specifically, function capsule  818   a  includes first function  815   a  and first authentication module  855   a . First function  815   a  includes second function  815   b  and second authentication module  855   b . In this embodiment, first authentication module  855   a  includes copies  426   c ′,  426   d ′ of secret keys  426   c ,  426   d  stored in SIM card  424  and second authentication module  855   b  includes copies  426   e ′,  426   x ′ of secret keys  426   e ,  426   x ′ stored in SIM card  424 . Here, key  426   c ′ may be used for accessing first function  815   a , key  426   d ′ may used for authenticating the user to utilize first function  815   a , key  426   e ′ may be used for accessing second function  815   b , and key  426   x ′ may be used for authenticating the user to utilize second function  815   b.    
     Moreover, to provide additional protection,  FIG. 10  shows that SIM card  924  coupled to mobile terminal  922  includes network key  926   a , server key  926   b , and capsule key  926   c . Mobile network  910  includes copy  926   a ′ of network key  926   a  to authenticate an intended user to mobile network  910 . Server  914  includes copy  926   b ′ of server key  926   b  to authenticate the intended user to server  914  (e.g., a data server). Function capsule  918  downloaded to mobile terminal  922  (e.g., from server  914  via mobile network  910 ) includes copy  926   c ′ of capsule key  926   c  to authenticate the intended user so that the intended user can utilize a function of function capsule  918  on mobile terminal  922 . 
     In addition, and/or in an alternative to the above described embodiment, server  914  of  FIG. 10  (and/or another server) may be used to revoke (or erase) key  926   a , key  926   b , and/or key  926   c  in SIM card  924  using key  926   b ′ (and/or another key). In one embodiment, keys  926   a ,  926   b ,  926   c  (or another key) in SIM card  924  may be revoked wirelessly via mobile network  910 . 
     Referring now to  FIG. 11 , an embodiment for providing keys to SIM card  1024  of an intended user pursuant to the present invention is shown. The embodiment includes key writing or burning site  1000  (e.g., a music retailer, a mobile phone retailer, etc.). Key writing or burning site  1000  may be connected to authentication server  1050  (and/or another server) via network  1020  (e.g., the Internet) so that copy  1026 ′ of new authentication key (or keys)  1026  can be written and/or burned into SIM card  1024 . Key writing or burning site  1000  can be made accessible to the intended user at a time when SIM card  1024  is purchased, at a time when the intended user desires to receive a function (e.g., a music playing function, a call waiting function, a caller identification function, etc.), and/or any other time. Specifically, in one embodiment, key writing or burning site  1000  allows the intended user to purchase a desired function for a mobile client and burns and/or writes authentication key  1026 ′ into SIM card  1024  to authenticate the user to the desired function upon the purchase of the function. 
     In addition, key writing or burning site  1000  may be connected to SIM card  1024  via a mobile network (e.g., network  10 ,  410 , and/or  910 ) and then wirelessly burns and/or writes copy  1026 ′ of new authentication key  1026  into SIM card  1024 . Further, authentication key  1026  (and/or another key) in server  1050  may be used to later revoke (or erase) copy  1026 ′ of key  1026  written into SIM card  1024 . In one embodiment, copy  1026 ′ of key  1026  may be revoked wirelessly (e.g., via the mobile network that was used to write copy  1026 ′ of key  1026  into SIM card  1024 ). 
     In general, according to the foregoing, the invention provides a method for providing secure functions to a mobile client using a SIM card, as diagramed in  FIG. 12 . At block  1202 , a random number (e.g., a 128-bit number) is sent to a mobile client (MC) from within a mobile network. At block  1204 , the mobile client computes a signed response (e.g., a 32-bit response) based on the random number sent to the mobile client with an authentication algorithm using a first authentication key. At block  1206 , upon receiving the signed response from the mobile client, the mobile network repeats the calculation to verify the identity of an intended user. At block  1208 , if the signed response received by the network agrees with the calculated value, the mobile client has been successfully authenticated and moves to block  1210 . If the values do not match, the connection to the network is terminated. 
     At block  1210 , a function capsule is downloaded from the mobile network to the mobile client. At step  1212 , a second random number (e.g., a second 128-bit number) is provided to the mobile client from the downloaded function capsule. At block  1214 , the mobile client computes a second signed response (e.g., a second 32-bit response) based on the random number provided to the mobile client with a second authentication algorithm using a second authentication key. At block  1216 , using a copy of the second authentication key, the downloaded function capsule repeats the calculation to verify the identity of the intended user. At block  1218 , if the signed response agrees with the calculated value, the mobile client has been successfully authenticated and moves to block  1220  to access the downloaded function capsule (and/or to utilize a function of the downloaded function capsule). If the values do not match, the access to the downloaded function capsule is denied. 
     In addition, one or more encryption keys may be used to encrypt and decrypt the data communicated between the mobile client and the mobile network and/or between the mobile client and the function capsule. As an example, encryption of the voice and data communications can be accomplished through use of an encryption algorithm. The mobile client begins encryption and decryption of data using the encryption algorithm and one or more of the encryption keys. 
     Moreover, an authentication server and/or another server may be used to remotely revoke the second authentication key and/or another key (e.g., the first authentication key) via the mobile network. 
     Lastly, an authentication and/or encryption key may have a private key and a related but different public key, a copy of which is made available outside the SIM card. A challenge may then be supplied to the SIM card and a response is generated using the private key. The response may be checked by the use of the related public key. Thus, if the private key is held only within the SIM card then only the SIM card can generate an authentication response that would work with the public key value. 
     Referring now to  FIG. 13 , an embodiment of a key management system that incorporates stateless key management modules (hereafter referred to as stateless modules or SMs for convenience) is illustrated. In  FIG. 13 , smartcard  1300  (e.g., a hardware security module or a SIM) is configured to manage multiple remote stateless modules (or SMs)  1310 . 
     Stateless modules may provide key enforcement and/or usage functions that are, in effect, separated out from the main key management functions provided by a smartcard. For example, a smartcard may provide all of the services for secure key management such as generating and destroying keys, establishing and enforcing key policy, using keys, providing key backup and secure key storage and communicating with peers. Inherently, these operations require that the smartcard keep track of its current state. For example, the smartcard must keep track of all keys it generated and it must maintain state information associated with each of these keys. This information may be used, for example, to determine the entity to which each key was issued and when to destroy or revoke keys. In contrast, the stateless modules provide a mechanism for securely receiving keys and using keys. The stateless modules do not generate keys or conduct peer-to-peer communication. Consequently, they typically must communicate with a key manager to obtain the keys needed by a mobile client (e.g., a mobile phone device, a PDA, etc.). 
     A stateless module does not need to maintain state information to receive keys and use keys. When a stateless module boots up, the only key information it has is an identity key that was stored in nonvolatile memory. However, this information is stateless because it never changes. To perform its tasks, the stateless module may be configured to establish a secure connection with a smartcard using its identity key. This secure connection enables the stateless module to perform the basic operations of receiving and using keys and/or data. These operations do not, however, require that the stateless module maintain the state of these keys. Rather, the stateless module merely needs to use the keys within a secure boundary and enforce any policy received with the key. As an example, after the smartcard securely sends keys to the stateless module these keys may be used to decrypt data and/or keys for a mobile client (e.g., a mobile phone device, a PDA, etc.). In addition, the stateless module may send secured (e.g., encrypted and/or authenticated) data to a designated device via a secure connection. 
     The stateless module provides a secure usage environment that may be remotely separated from, yet cryptographically secured to (e.g., using operations that may include encryption, decryption, authentication, etc.), the smartcard. In particular, keys and data within the stateless module are protected by hardware (e.g., the physical constraints provided by the integrated circuit, aka chip). In addition, the stateless module may be configured to prevent the keys and data from being exported from the chip without encryption (or in the clear). Moreover, as illustrated in  FIG. 14 , a key transfer protocol may be established between stateless module  1410  and smartcard  1400  to allow keys generated in smartcard  1400  to be securely transferred to stateless module  1410 . 
     As is shown in  FIG. 14  (and discussed above), encrypted link (communication channel)  1430  may be used to effectively extend the security boundary of smartcard  1400  to include the stateless module  1410 . Encrypted link  1430  allows for key material to be transferred over an insecure communication medium (i.e. network and/or Internet) between smartcard  1400  and stateless module  1410 . 
       FIG. 14  also illustrates that stateless module  1410  may receive encrypted key material from smartcard  1400  for use with local cryptographic accelerator  1440 . Cryptographic accelerator  1440  also may be implemented within the effective security boundary. For example, cryptographic accelerator  1440  and stateless module  1410  may be implemented on the same integrated circuit. Alternatively, keys and data transferred between these components may be encrypted. 
     Thus, cleartext and ciphertext may be sent to cryptographic accelerator  1440  without exposing the key material outside of the security boundary. As a result, any key material that is decrypted locally by stateless module  1410  may never be exposed outside the security boundary. 
     Typically, a stateless module is embedded inside a mobile client that uses cryptographic services. For example, the stateless module may be implemented in mobile clients or end-user devices, such as cell phones, laptops, etc., that need some form of data security. The stateless module should be integrated into other chips (e.g., a main processor) within these devices. In this way, the stateless module may provide cost effective remote key management for a mobile client (e.g., a mobile phone device, a PDA, etc.). The security boundary to this mobile client is contained and managed through the stateless module by the smartcard key management system with minimal impact on the rest of the mobile client. 
     To support the above described key management scheme (i.e., to provide a high level of security at a relatively low cost, while consuming a relatively small amount of space on a mobile client), a stateless module provides mechanisms for securely loading one or more keys into the stateless module, securely storing the keys and securely using the keys. Embodiments of exemplary stateless modules that provide such mechanisms are provided in U.S. Patent Application Ser. No. 60/615,290, entitled “Stateless Hardware Security Module,” filed on Oct. 1, 2004, and assigned to the assignee of the present application, the entire content of which is incorporated herein by reference. 
     While certain exemplary embodiments have been described in detail and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive of the broad invention. It will thus be recognized that various modifications may be made to the illustrated and other embodiments of the invention described above, without departing from the broad inventive scope thereof. For example, a system using SIM cards and GSM mobile network has been illustrated, but it should be apparent that the inventive concepts described above would be equally applicable to systems that use other types of smartcards and/or other types of mobile network. In view of the above it will be understood that the invention is not limited to the particular embodiments or arrangements disclosed, but is rather intended to cover any changes, adaptations or modifications which are within the scope and spirit of the invention.