Security in GSM

Security services

 access control/authentication

 user SIM (Subscriber Identity Module): secret PIN (personal identification number)

 SIM network: challenge response method

 confidentiality

 voice and signaling encrypted on the wireless link

(after successful authentication)

 anonymity

 temporary identity TMSI

 newly assigned at each new location update (LUP)

 encrypted transmission


3 algorithms specified in GSM

 A3 for authentication (“secret”, open interface)

 A5 for encryption (standardized)

 A8 for key generation (“secret”, open interface)

(Temporary Mobile Subscriber Identity)