Patent ID: 9553729
Date: 2017-01-24
CPC Classifications: H04L

Claim:
1. A method for authenticating a reader to a radio tag, comprising the following steps, which are implemented by the tag: a step of receiving at least a ciphered piece of information and a data item allowing determination of an index for identifying an authentication coupon for the reader, said piece of information being ciphered by applying a reversible operation to the authentication coupon associated to the index and to a predefined redundancy value, an operation of calculating a current authentication coupon for the reader as a function of the index determined from the received data item and of a regeneration key owned by the tag, an operation of deciphering the received piece of information ciphered by the reversible operation, which is applied to the calculated current authentication coupon and to the ciphered piece of information, and an operation of checking the deciphered piece of information to verify that the calculated current coupon corresponds to the authentication coupon used by the reader in order to cipher the predefined redundancy value.