Abstract: The invention relates to a method of authenticating a radio tag by a radio reader, the tag possessing an identifier accessible to the reader via a database of tag identifiers, comprising: dispatching an authentication request by the reader to the tag, dispatching by the tag, a response, calculated by applying a first function to at least the identifier, a calculation by the tag and by the reader of a new identifier, by applying a second function to the identifier, comprising: if the response dispatched by the tag corresponds to a result obtained by applying said first function to an identifier of the base, a dispatching by the reader a first value, calculated by applying a third function to said identifier of the base.

Abstract: A method for authenticating an entity by a verifier, the entity having an identifier, the verifier having a pair of private and public keys, comprising: sending to the entity a first random number selected by the verifier; a step wherein the entity encrypts a value by means of the public key of the verifier, said value including the first random number and an authentication datum on which the identifier of the entity depends; and the entity of said encrypted value sending a reply to authenticate said entity. The invention can be applied to the field of low-cost cryptography, especially the field of radio-identification.

Abstract: A method for authenticating an entity by a verifier, the entity having an identifier, the verifier having a pair of private and public keys, comprising: sending to the entity a first random number selected by the verifier; a step wherein the entity encrypts a value by means of the public key of the verifier, said value including the first random number and an authentication datum on which the identifier of the entity depends; and the entity of said encrypted value sending a reply to authenticate said entity. The invention can be applied to the field of low-cost cryptography, especially the field of radio-identification.

Abstract: The invention relates to a method of authenticating a radio tag by a radio reader, the tag possessing an identifier accessible to the reader via a database of tag identifiers, comprising: dispatching an authentication request by the reader to the tag, dispatching by the tag, a response, calculated by applying a first function to at least the identifier, a calculation by the tag and by the reader of a new identifier, by applying a second function to the identifier, comprising: if the response dispatched by the tag corresponds to a result obtained by applying said first function to an identifier of the base, a dispatching by the reader a first value, calculated by applying a third function to said identifier of the base.