Authentication method in data communication and smart card

Abstract

The invention sets forth an authentication method for use in a system including a first entity and a second entity in a network, the first entity being adapted to authenticate the second entity and data received therefrom, both first and second entities storing the same secret key. The method is implemented in a smart card such as a USIM card, including: a memory storing authentication algorithms and keys; means for receiving a message authenticating code and other parameters; means for computing an expected code from said other parameters and from said secret key; means for comparing said message authenticating code received and said expected code; and means for aborting authentication if the message authenticating code received and the expected code do not match. The smart card further comprises a failure counter adapted to store the number of abortion occurrences, and means for updating said failure counter every time the comparing means indicate that said message authenticating code and said expected code do not match. Thanks to its built-in failure counter and the fact that the updating of this counter is controlled from inside the card, the card becomes tamper-resistant against reiterated fraudulent authentication attempts.