# US 10,321,309 B2 · Apparatuses and methods for wireless communication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,321,309 B2 - Document ID: US10321309B2 - Status: Granted - Kind: B2 - Application number: 15/913,823 - Filed: 2018-03-06 - Published: 2018-07-12 - Granted: 2019-06-11 - Earliest claimed: 2014-11-03 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Soo Bum Lee; Gavin Bernard Horn; Anand Palanigounder - Web page: https://patentgrep.com/patent/US10321309B2 ## CPC - H04W 12/041: Key generation or derivation - H04W 12/0431: Key distribution or pre-distribution; Key agreement - H04W 12/0433: Key management protocols - H04W 12/06: Authentication - H04L 2463/061: applying further key derivation, e.g. deriving traffic keys from a pair-wise master key - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract One feature pertains to a method operational at a device. The method includes performing key agreement with a core network device, and generating an authentication session key based in part on a secret key shared with a home subscriber server (HSS), where the authentication session key is known to the core network device. The method further includes generating a mobility session key based in part on the authentication session key, where the mobility session key is known to a mobility management entity (MME) served by the core network device and serving the device. The method also includes cryptographically securing data sent from the device to a wireless communication network using the mobility session key. ## Claims ### Claim 1 A method operational at a device, the method comprising: wirelessly transmitting a non-access stratum (NAS) message to a radio access node, wherein the NAS message propagates to a mobility management entity (MME) and then to a separate core network device serving the MME; obtaining an authentication session key that is based in part on a secret key known by a home subscriber server (HSS) configured to serve the core network device, the authentication session key known to the core network device, wherein the secret key is derived from a root key known by the device and an authentication center; obtaining a mobility session key that is based in part on the authentication session key, the mobility session key known to a mobility management entity (MME) served by the core network device and serving the device; and cryptographically securing data sent from the device to a wireless communication network based on the mobility session key. ### Claim 2 (depends on 1) The method of claim 1, further comprising: obtaining different mobility session keys for different MMEs wherein the different mobility session keys are based in part on the authentication session key. ### Claim 3 (depends on 1) The method of claim 1, further comprising: receiving key derivation data from the MME after successfully performing key agreement with the core network device, the key derivation data enabling the device to derive the mobility session key. ### Claim 4 (depends on 3) The method of claim 3, wherein the key derivation data includes an MME identification value identifying the MME serving the device, and the method further comprises: obtaining the mobility session key based further in part on the MME identification value. ### Claim 5 (depends on 4) The method of claim 4, wherein the MME identification value is a globally unique MME identifier (GUMMEI). ### Claim 6 (depends on 4) The method of claim 4, wherein the MME identification value is an MME group identifier (MMEGI). ### Claim 7 (depends on 1) The method of claim 1, wherein the core network device is an authentication session key anchor function device. ### Claim 8 (depends on 1) The method of claim 1, wherein the root key, an integrity key, and a cipher key are shared secret keys shared between the device and the core network, and wherein the integrity key and the cipher key are derived from the root key. ### Claim 9 (depends on 1) The method of claim 1, wherein obtaining the mobility session key includes deriving the mobility session key using a key derivation function having as inputs the authentication session key and at least one of an MME identification value uniquely identifying the MME, and a counter value Key Count. ### Claim 10 (depends on 1) The method of claim 1, further comprising: receiving notification of MME relocation wherein the notification comprises an MME identifier uniquely identifying a second MME attempting to serve the device; obtaining a second mobility session key wherein the second mobility session key is based in part on the authentication session key and the MME identifier uniquely identifying the second MME. ### Claim 11 (depends on 1) The method of claim 1, further comprising: deriving a node B key that is based in part on the mobility session key; and encrypting data transmitted to a radio access node serving the device using the node B key. ### Claim 12 A device comprising: a wireless communication interface configured to send and receive data to and from a wireless communication network; and a processing circuit communicatively coupled to the wireless communication interface, the processing circuit configured to: wirelessly transmit a non-access stratum (NAS) message to a radio access node wherein the NAS message is passed to a mobility management entity (MME) and then to a core network device serving the MME wherein the core network device is a key anchor; obtain an authentication session key that is based in part on a secret key known by a home subscriber server (HSS) configured to serve the core network device, the authentication session key known to the core network device, wherein the secret key is derived from a root key known by the device and an authentication center; obtain a mobility session key that is based in part on the authentication session key, the mobility session key known to a mobility management entity (MME) served by the core network device and serving the device; and cryptographically secure data sent from the device to the wireless communication network based on the mobility session key. ### Claim 13 (depends on 12) The device of claim 12, wherein the processing circuit is further configured to: obtain different mobility session keys for different MMEs wherein the different mobility session keys are based in part on the authentication session key. ### Claim 14 (depends on 12) The device of claim 12, wherein the processing circuit is further configured to: receive key derivation data from the MME after successfully performing key agreement with the core network device, the key derivation data enabling the device to derive the mobility session key. ### Claim 15 (depends on 14) The device of claim 14, wherein the key derivation data includes an MME identification value identifying the MME serving the device, and the processing circuit is further configured to: obtain the mobility session key based further in part on the MME identification value. ### Claim 16 (depends on 12) The device of claim 12, wherein obtain the mobility session key includes having the processing circuit further configured to derive the mobility session key using a key derivation function having the authentication session key, an MME identification value uniquely identifying the MME, and a number used once (nonce) as inputs. ### Claim 17 (depends on 12) The device of claim 12, wherein the processing circuit is further configured to: receive notification of MME relocation wherein the notification comprises an MME identifier uniquely identifying a second MME attempting to serve the device; obtain a second mobility session key that is based in part on the authentication session key and the MME identifier uniquely identifying the second MME. ### Claim 18 A device comprising: means for wirelessly transmitting a non-access stratum (NAS) message to a radio access node wherein the NAS message is passed to a mobility management entity (MME) and then to a core network device serving the MME wherein the core network device is a key anchor; means for obtaining an authentication session key that is based in part on a secret key known by a home subscriber server (HSS) configured to serve the core network device, the authentication session key known to the core network device, wherein the secret key is derived from a root key known by the device and an authentication center; means for obtaining a mobility session key that is based in part on the authentication key, the mobility session key known to a mobility management entity (MME) served by the core network device and serving the device; and means for cryptographically securing data sent from the device to a wireless communication network based on the mobility session key. ### Claim 19 (depends on 18) The device of claim 18, further comprising: means for generating different mobility session keys for different MMEs wherein the different mobility session keys are based in part on the authentication session key. ### Claim 20 A non-transitory computer-readable storage medium having instructions stored thereon that are operational at a device, the instructions when executed by at least one processor causes the processor to: wirelessly transmit a non-access stratum (NAS) message to a radio access node wherein the NAS message is passed to a mobility management entity (MME) and then to a core network device serving the MME, wherein the core network device is a key anchor; obtain an authentication session key that is based in part on a secret key known by a home subscriber server (HSS) configured to serve the core network device, the authentication session key known to the core network device, wherein the secret key is derived from a root key known by the device and an authentication center; obtain a mobility session key that is based in part on the authentication session key, the mobility session key known to a mobility management entity (MME) served by the core network device and serving the device; and cryptographically securing data sent from the device to a wireless communication network based on the mobility session key. ### Claim 21 (depends on 20) The non-transitory computer-readable storage medium of claim 20, wherein the instructions when executed by the processor further causes the processor to: obtain different mobility session keys for different MMEs wherein the different mobility session keys are based in part on the authentication session key. ### Claim 22 (depends on 1) The method of claim 1, further comprising: performing key agreement with the core network device.