# US 11,121,871 B2 · Secured key exchange for wireless local area network (WLAN) zero configuration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,121,871 B2 - Document ID: US11121871B2 - Status: Granted - Kind: B2 - Application number: 16/166,200 - Filed: 2018-10-22 - Published: 2020-04-23 - Granted: 2021-09-14 - Earliest claimed: 2018-10-22 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Chih-Wei Hsiao; Chih-Wen Chao; Wei-Hsiang Hsiung; Ya-Hsuan Tsai - Web page: https://patentgrep.com/patent/US11121871B2 ## CPC - H04L 9/0841: {involving Diffie-Hellman or related key agreement protocols} - H04L 9/3073: {involving pairings, e.g. identity based encryption [IBE], bilinear mappings or bilinear pairings, e.g. Weil or Tate pairing} - H04L 9/0844: {with user authentication or key authentication, e.g. ElGamal, MTI, MQV-Menezes-Qu-Vanstone protocol or Diffie-Hellman protocols using implicitly-certified keys} - H04L 9/085: {Secret sharing or secret splitting, e.g. threshold schemes} - H04L 63/0435: {wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption (cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06)} - H04W 12/03: Protecting confidentiality, e.g. by encryption - H04W 12/041: Key generation or derivation - H04W 12/047: without using a trusted network node as an anchor - H04W 12/086: using security domains - H04W 12/50: Secure pairing of devices - H04W 76/10: Connection setup - H04L 2209/80: Wireless - H04W 84/12: WLAN [Wireless Local Area Networks] - H04W 88/08: Access point devices - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A technique to secure a wireless communication link that is being shared among a wireless access point (AP), and each of a set of wireless clients (each a mobile station (STA)) that are coupled to the AP over the communication link. A typical implementation is a WPA2-PSK communication link. In this approach, and in lieu of a single secret key being shared by all AP-STA pairs, each AP-STA pair derives its own unique WLAN shared secret, preferably via a Diffie-Hellman (DH) key exchange. The WLAN shared secret is then used to generate WPA2-PSK keys, namely, pairwise master key (PMK) and pairwise transient key (PTK), that establish an 802.11 standards-compliant secure link. ## Claims ### Claim 1 A method to establish a secure session to a wireless network access point (AP) in an automated manner, comprising: outputting a first public key of a first cryptographic key pair, the first cryptographic key pair uniquely associated with the AP, the first public key output in a first element of a management frame issued from the AP, the management frame also including a second element distinct from the first element and that includes a portion of the first public key; receiving a second public key of a second cryptographic key pair, the second cryptographic key pair uniquely associated with a mobile station (STA) seeking to associate with the AP, the second public key output in a management frame issued from the STA; computing a shared secret using the second public key received from the STA and a private key of the first cryptographic key pair, the shared secret being uniquely associated with the AP and STA pair; and using the shared secret to complete a handshake between the AP and the STA, thereby setting up a secure communication link between the AP and STA pair. ### Claim 2 (depends on 1) The method as described in claim 1 wherein the handshake is a Wi-Fi Protected Access 2-Pre-Shared Key (WPA2-PSK) handshake. ### Claim 3 (depends on 1) The method as described in claim 1 wherein the first cryptographic key pair and the second cryptographic key pair are each Diffie-Hellman key pairs. ### Claim 4 (depends on 1) The method as described in claim 1 wherein the management frame issued from the AP is one of: a beacon, and a probe response. ### Claim 5 (depends on 1) The method as described in claim 1 wherein the management frame issued from the STA is an association request. ### Claim 6 (depends on 1) The method as described in claim 1 wherein the first element is a vendor information element (VIE) and the second element is a Service Set IDentifier (SSID) element, wherein comparison by the STA of the portion to the first public key enables the STA to verify that the AP is not operating in a rogue manner. ### Claim 7 An apparatus configured as an access point in a wireless network, comprising: a processor; computer memory holding computer program instructions executed by the processor, the computer program instructions comprising program code configured to: output a first public key of a first cryptographic key pair, the first cryptographic key pair uniquely associated with the AP, the first public key output in a first element of a management frame issued from the AP, the management frame also including a second element distinct from the first element and that includes a portion of the first public key; receive a second public key of a second cryptographic key pair, the second cryptographic key pair uniquely associated with a mobile station (STA) seeking to associate with the AP, the second public key output in a management frame issued from the STA; compute a shared secret using the second public key received from the STA and a private key of the first cryptographic key pair, the shared secret thereafter being uniquely associated with the AP and STA pair; and use the shared secret to complete a handshake between the AP and the STA, thereby setting up a secure communication link between the AP and STA pair. ### Claim 8 (depends on 7) The apparatus as described in claim 7 wherein the handshake is a Wi-Fi Protected Access 2-Pre-Shared Key (WPA2-PSK) handshake. ### Claim 9 (depends on 7) The apparatus as described in claim 7 wherein the first cryptographic key pair and the second cryptographic key pair are each Diffie-Hellman key pairs. ### Claim 10 (depends on 7) The apparatus as described in claim 7 wherein the management frame issued from the AP is one of: a beacon, and a probe response. ### Claim 11 (depends on 7) The apparatus as described in claim 7 wherein the management frame issued from the STA is an association request. ### Claim 12 (depends on 7) The apparatus as described in claim 7 wherein the first element is a vendor information element (VIE) and the second element is a Service Set IDentifier (SSID) element, wherein comparison by the STA of the portion to the first public key enables the STA to verify that the AP is not operating in a rogue manner. ### Claim 13 A computer program product in a non-transitory computer readable medium for use in a data processing system configured as an access point a wireless network, the computer program product holding computer program instructions executed by the data processing system, the computer program instructions comprising program code configured to: output a first public key of a first cryptographic key pair, the first cryptographic key pair uniquely associated with the AP, the first public key output in a first element of a management frame issued from the AP, the management frame also including a second element distinct from the first element and that includes a portion of the first public key; receive a second public key of a second cryptographic key pair, the second cryptographic key pair uniquely associated with a mobile station (STA) seeking to associate with the AP, the second public key output in a management frame issued from the STA; compute a shared secret using the second public key received from the STA and a private key of the first cryptographic key pair, the shared secret thereafter being uniquely associated with the AP and STA pair; and use the shared secret to complete a handshake between the AP and the STA, thereby setting up a secure communication link between the AP and STA pair. ### Claim 14 (depends on 13) The computer program product as described in claim 13 wherein the handshake is a Wi-Fi Protected Access 2-Pre-Shared Key (WPA2-PSK) handshake. ### Claim 15 (depends on 13) The computer program product as described in claim 13 wherein the first cryptographic key pair and the second cryptographic key pair are each Diffie-Hellman key pairs. ### Claim 16 (depends on 13) The computer program product as described in claim 13 wherein the management frame issued from the AP is one of: a beacon, and a probe response. ### Claim 17 (depends on 13) The computer program product as described in claim 13 wherein the management frame issued from the STA is an association request. ### Claim 18 (depends on 13) The computer program product as described in claim 13 wherein the first element is a vendor information element (VIE) and the second element is a Service Set IDentifier (SSID) element, wherein comparison by the STA of the portion to the first public key enables the STA to verify that the AP is not operating in a rogue manner. ### Claim 19 An apparatus configured as a mobile station (STA) operating in a wireless network, comprising: a processor; computer memory holding computer program instructions executed by the processor, the computer program instructions comprising program code configured to: receive a first public key of a first cryptographic key pair, the first cryptographic key pair uniquely associated with an access point (AP) to which the STA seeks to associate, the first public key having been output in a first element of a management frame issued from the AP, the management frame also including a second element distinct from the first element and that includes a portion of the first public key; output a second public key of a second cryptographic key pair, the second cryptographic key pair uniquely associated with the STA, the second public key output in a management frame issued from the STA; compute a shared secret using the first public key received from the AP and a private key of the second cryptographic key pair, the shared secret thereafter being uniquely associated with the AP and STA pair; and use the shared secret to complete a handshake between the AP and the STA, thereby setting up a secure communication link between the AP and STA pair. ### Claim 20 (depends on 19) The apparatus as described in claim 19 wherein the handshake is a Wi-Fi Protected Access 2-Pre-Shared Key (WPA2-PSK) handshake. ### Claim 21 (depends on 19) The apparatus as described in claim 19 wherein the first cryptographic key pair and the second cryptographic key pair are each Diffie-Hellman key pairs. ### Claim 22 (depends on 19) The apparatus as described in claim 19 wherein the first element of the management frame issued from the AP is a vendor information element (VIE) and the second element is a Service Set IDentifier (SSID) element, and wherein the program code is further configured to validate that the portion is part of the first public key, thereby confirming that the AP is not operating in a rogue manner.