Patent ID: 6934531

Claim:
Procedure for the increased security of authentication processes in digital mobile radio systems, comprising: storing several different secret SIM-specific keys (KI) in a mobile radio network and in a subscriber identification module (SIM); pre-configuring and storing a RAND/SRES/KC authentication triplet for each one of the several secret keys (KI) stored in the mobile radio network; selecting and sending a random value RAND of one of the pre-configured authentication triplets to the subscriber identification module (SIM) by the mobile radio network; selecting one of the secret keys (KI) stored in the subscriber identification module (SIM) and calculating from the random value RAND and the selected one of the secret keys (KI) a corresponding value for a signed response (SRES) and cipher key (KC) and sending the calculated values to the mobile radio network by the subscriber identification module (SIM); and comparing the signed response (SRES) to all SRES values for the random value RAND by the mobile radio network and validating the subscriber's authentication if a match is found.