Gemalto Sa

Axalto S.a.

Thales Dis France Sa

Stéphanie Salgado

David Vigilant

Guillaume Fumaroli

Eddy Bernard

Jorge Sevilla Abellan

A device (CD) is intended for controlling authenticity of a code received with a message by an electronic device (ED) and resulting from application to this message of a bijective algorithm with at least one predetermined key. This device (CD) has i) a first computation means (CM) arranged for applying partly this bijective algorithm with this predetermined key, from a starting step to a chosen intermediate step, to the received message, in order to get a first result, ii) a second computation means (CM) arranged for applying partly in a reverse manner the bijective algorithm with the predetermined key, from an ending step to this chosen intermediate step, to the received code while using the received message, in order to get a second result, and iii) a comparison means (CM) arranged for comparing these first and second results and for outputting an information representative of the authenticity of the received code when the first and second results are identical.

Control method and device for controlling authenticity of codes resulting from application of a bijective algorithm to messages

The invention relates to a method for securing the execution of a cryptographic algorithm A against fault attacks. Given a cryptographic key KO and a message M, the cryptographic algorithm A is set to compute a value A(KO,M). Given a relationship R between A(KO,M) and A(f(K),g(M)), where f and g are two bijections, and where f is different from the identity function, the method comprises: a. computing the expected result A(KO,M) of the cryptographic algorithm b. computing a modified result A(f(K),g(M)), by applying the cryptographic algorithm A on a modified key f(K) and on a message g(M), c. checking whether the relationship R between the values A(KO,M) and A(f(K),g(M)) computed in the two preceding steps is verified d. detecting an attack if the relationship R is not verified. The invention also relates to a cryptographic device embodying the above method.

Cryptographic algorithm fault protections

An authentication method including operation of a personal token, a personal token for a terminal in a communication network, an authentication server, and a computer program for an authentication server. The secure server producing derived key material on the basis of a random and a secret key (K), said personal token including program instructions for re-computing the derived key material (Ck, Ik) on the basis of the received random and the secret key (K) as stored in the personal token. The personal token includes program instructions for using a re-computed part of the derived key material in order to interpret the received additional data.

Method for securing an authentication and key agreement protocol

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.

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Montrouge, France

Stéphanie Salgado