Patent ID: 8458469

Claim:
A method of communication between an electronic tag and a reader, for an authentication of the tag by the reader, in which: a) the reader sends at least one datum to the tag, b) the tag calculates a combination of at least the datum of the reader and a secret specific to the tag, and communicates the result of the combination to the reader for verification of the authenticity of the tag by the reader, wherein said combination is calculated by using a current secret value obtained from a succession of pseudo-random secret values specific to the tag and capable of being determined by the reader, a single current secret value being intended to be used by the tag a limited number of times, wherein a first pseudo-random generator is provided in the tag in order to determine a new current secret value, replacing an old value immediately preceding the new value in said succession, wherein a second pseudo-random generator is provided in order to operate in a coordinated manner with the first generator and is capable of being queried by the reader in order to know a current secret value of the tag, and wherein the first and the second pseudo-random generators are able to receive at the input a first number in order to deliver at the output a second number, and the first and the second pseudo-random generators deliver, in operation, from a first number at the input: a second number comprising a first secret value in order to calculate said combination, and a third number intended to be stored in the memory of the tag and respectively of the reader in order to be supplied, as the first number, at the input of the first and respectively of the second generator, for a following operation, in order to obtain a second secret value which immediately follows the first secret value in said succession.