# US 8,788,807 B2 · Privacy protection in communication systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,788,807 B2 - Document ID: US8788807B2 - Status: Granted - Kind: B2 - Application number: 11/621,916 - Filed: 2007-01-10 - Published: 2007-07-19 - Granted: 2014-07-22 - Earliest claimed: 2006-01-13 - Assignees: QUALCOMM Incorporated - Applicants: Adrian Escott; James Semple - Inventors: Adrian Escott; James Semple - Web page: https://patentgrep.com/patent/US8788807B2 ## CPC - H04L 63/0414: {during transmission, i.e. party's identity is protected against eavesdropping, e.g. by using temporary identifiers, but is known to the other party or parties involved in the communication} - H04L 9/083: {involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]} - H04L 9/3236: {using cryptographic hash functions} - H04L 9/3297: {involving time stamps, e.g. generation of time stamps} - H04L 63/061: {for key exchange, e.g. in peer-to-peer networks (cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838)} - H04L 63/062: {for key distribution, e.g. centrally by trusted party (cryptographic mechanisms or cryptographic arrangements for key distribution involving a central third party H04L9/0819)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Methods and apparatus for protecting user privacy in a shared key system. According to one aspect, a user generates a derived identity based on a key and a session variable, and sends the derived identity to an application. In one embodiment, a key server may be used to receive the derived identity from the application, and return a sub-key to the application to use for encrypting communications with the user. ## Claims ### Claim 1 A method for protecting user privacy comprising: receiving, from a user, at a key server, a first derived identity generated from a key stored at a user's device and at least one first session parameter comprising an application identity and a first session variable associated with a first session, wherein the at least one first session parameter is not received by the key server; identifying said key based upon said first derived identity at the key server, wherein said key and said first derived identity are pre-stored at the key server with a plurality of different keys, different first derived identifiers, and possible values of the at least one first session parameter; generating a first traffic key based upon said first derived identity at the key server if the application identity and the key have the same value as a corresponding application identity and key stored at the key server; and sending the first traffic key to an application to enable encrypted communication. ### Claim 2 (depends on 1) The method of claim 1, wherein said first session variable comprises a counter value. ### Claim 3 (depends on 1) The method of claim 1, wherein said first session variable comprises a time stamp. ### Claim 4 (depends on 1) The method of claim 1, wherein said first session variable comprises the output of a pseudorandom number generator. ### Claim 5 A key server for protecting user privacy comprising: a receiver for receiving, from a user, a first derived identity generated from a key stored at a user's device and at least one first session parameter comprising an application identity and a first session variable and a second derived identity generated from the key and at least one second session parameter comprising an application identity and a second session variable, wherein the at least one first session parameter and the at least one second session parameter are not received by the key server; a processor for identifying said key based upon said first derived identity and from said second derived identity, wherein said key and said first and second derived key identity are pre-stored at the key server with a plurality of different keys, different first and second derived identifiers, and possible values of the at least one first session parameter and possible values of the at least one second session parameter; a generator for generating a first traffic key based upon said first derived identity, if the application identity of the at least one first session parameter and the key have the same value as a corresponding application identity and key stored at the key server, and for generating a second traffic key with said second derived identity, if the application identity of the at least one second session parameter and the key have the same value as a corresponding application identity and key stored at the key server; and a transmitter to send the first traffic key and the second traffic key to an application to enable encrypted communication. ### Claim 6 (depends on 5) The key server of claim 5, wherein said first session variable comprises a counter value. ### Claim 7 (depends on 5) The key server of claim 5, wherein said first session variable comprises a time stamp. ### Claim 8 (depends on 5) The key server of claim 5, wherein said first session variable comprises the output of a pseudorandom number generator. ### Claim 9 A non-transitory computer readable medium having instructions stored thereon, the stored instructions, when executed by a processor, cause the processor to perform a method comprising: receiving, from a user, at a key server, a first derived identity generated from a key stored at a user's device and at least one first session parameter comprising an application identity and a first session variable associated with a first session, wherein the at least one first session parameter is not received by the key server; identifying said key based upon said first derived identity at the key server, wherein said key and said first derived identity are pre-stored at the key server with a plurality of different keys, different first derived identifiers, and possible values of the at least one first session parameter; generating a first traffic key based upon said first derived identity at the key server if the application identity and the key have the same value as a corresponding application identity and key stored at the key server; and sending the first traffic key to an application to enable encrypted communication. ### Claim 10 (depends on 9) The non-transitory computer readable medium of claim 9, wherein said first session variable comprises a counter value. ### Claim 11 (depends on 9) The non-transitory computer readable medium of claim 9, wherein said first session variable comprises a time stamp. ### Claim 12 (depends on 9) The non-transitory computer readable medium of claim 9, wherein said first session variable comprises the output of a pseudorandom number generator. ### Claim 13 A key server for protecting user privacy comprising: a receiver for receiving, from a user, a first derived identity generated from a key stored a user's device and at least one first session parameter comprising an application identity and a first session variable, wherein the at least one first session parameter is not received by the key server; a processor for identifying said key based upon said first derived identity, wherein said key and said first derived key identity are pre-stored at the key server with a plurality of different keys, different first derived identifiers, and possible values of the at least one first session parameter; a generator for generating a first traffic key based upon said first derived identity, if the application identity and the key have the same value as a corresponding application identity and key stored at the key server; and a transmitter to send the first traffic key to an application to enable encrypted communication. ### Claim 14 (depends on 13) The key server of claim 13, wherein said first session variable comprises a counter value. ### Claim 15 (depends on 13) The key server of claim 13, wherein said first session variable comprises a time stamp. ### Claim 16 (depends on 13) The key server of claim 13, wherein said first session variable comprises the output of a pseudorandom number generator. ### Claim 17 A key server for protecting user privacy comprising: means for receiving, from a user, a first derived identity generated from a key stored a user's device and at least one first session parameter comprising an application identity and a first session variable, wherein the at least one first session parameter is not received by the key server; means for identifying said key based upon said first derived identity, wherein said key and said first derived key identity are pre-stored at the key server with a plurality of different keys, different first derived identifiers, and possible values of the at least one first session parameter; means for generating a first traffic key based upon said first derived identity, if the application identity and the key have the same value as a corresponding application identity and key stored at the key server; and means for sending the first traffic key to an application to enable encrypted communication.