TEILNEHMER AUTHENTIFIZIERUNG IN EINEM MOBILEN KOMMUNIKATIONSSYSTEM

An authentication procedure in a Global System for Mobile Communications (GSM)-based mobile communications system relies on a challenge and response principle. A 32-bit Signed Response (SRES) parameter is calculated by an A3 algorithm from a 128-bit random number (RAND) and a 128-bit authentication key Ki in a mobile station, and in an authentication center, and the SRES values are compared. A Cellular Authentication and Voice Encryption (CAVE) algorithm having a 152-bit input parameter and a 18-bit output parameter is employed as the A3 algorithm. Parameter adaptation functions are provided between the input parameter of the CAVE algorithm and the GSM-type input parameters, namely the random number RAND and the authentication key Ki, as well as between the output parameter of the CAVE algorithm and the GSM output parameter, namely the signed response SRES.