Patent ID: 7793102

Claim:
A method of mutually authenticating, firstly, a portable telecommunications object assigned a unique identifier and including a first wireless communications unit and, secondly, a public access terminal including a second wireless communications unit adapted to cooperate with said first wireless communications unit and a telecommunications unit for communicating via a telecommunications network, the method comprising: assigning said portable telecommunications object a wireless communication key; installing on said telecommunications network an authentication server adapted to determine the wireless communication key of the portable object from said unique identifier; sending the unique identifier of the portable object from the portable object to the public access terminal via said first and second wireless communications units; sending the unique identifier of the portable object from the public access terminal to the authentication server via said telecommunications unit; the authentication server determining the wireless communication key of the portable object from the unique identifier sent; the authentication server allocating said wireless communication key to a calculation unit; the calculation unit calculating a session key from said wireless communication key of the portable object and at least one random number; allocating said calculated session key to the public access terminal; the public access terminal sending the portable object a first message signed using the session key via said first and second wireless communications units; the portable object calculating the session key from the at least one random number contained in the first message and the wireless communication key; authenticating the public access terminal by verifying the signature of said first signed message; and the portable object sending the public access terminal a second message signed with the session key via said first and second wireless communications units and the public access terminal authenticating the portable object by verifying the signature of said second signed message.