Patent ID: 7627122

Claim:
A method for authentication of a radio communications network with a mobile station having an identity module, comprising: producing stacks of authentication vectors at the network end, each authentication vector including an authentication token with a sequence number and a mode parameter, wherein unique mode parameters are allocated to each stack such that the mode parameter has an identical value for all authentication tokens in the same stack; selecting an unused authentication vector from the respective stack for each new authentication; sending an authentication token, sequence number, and mode parameter of the selected unused authentication vector to the mobile station; and determining at the mobile station end by the identity module whether the received sequence number is accepted or rejected for the authentication, wherein the identity module is informed by the radio communications network as to which authentication tokens with an associated sequence number are located in the same stack, and wherein at least one sequence number is stored for each stack by the identity module, wherein the identity module accepts the received sequence number if it is greater than the at least one stored sequence number which corresponds to the received mode parameter, and wherein a numerical value, representative of acceptance or rejection of the received sequence number, is stored by the identity module for each mode parameter.