Idemia France

Nathan Reboud

Luk Bettale

Emmanuelle Dottax

Christophe Giraud

Guillaume Barbu

Nicolas Debande

Thomas Chabrier

Aurélien Greuet

Laurent Castelnovi

A processing method implemented by a first device including receiving first data including a challenge datum; obtaining key data including an encrypted cryptographic key which is masked by executing a cryptographic masking function; receiving an unmasking key; determining the encrypted cryptographic key by executing a cryptographic unmasking function on the basis of the unmasking key; determining a decrypted cryptographic key by a decryption by executing a decryption algorithm with white-box implementation on the basis of the encrypted cryptographic key; determining an answer datum by a cryptographic operation by executing a predetermined cryptographic algorithm on the basis of the decrypted cryptographic key and the challenge datum; and sending the answer datum to authenticate the first device.

Authentication of a device by a cryptographic process

The invention proposes a novel type of infective countermeasure against fault injection attacks. Instead of determining the injected error before amplifying it, the novel countermeasure applies the same diffusion function to two intermediate ciphers obtained by executing a cryptographic operation on an input. The error is therefore amplified within the same intermediate ciphers, referred to as infective ciphers after diffusion. It is then possible to use diffusion functions which do not map the cipher 0 as an output equal to 0. A cipher recomposed from bits of undiffused ciphers is also generated. These infective and recomposed ciphers are XOR-combined to provide an output cipher. This approach makes it possible to adapt, by simple duplication of the pairs and associated specific diffusion functions, the protection offered by the countermeasure to a desired number of injected faults.

Infective countermeasures

The invention relates to an electronic access pass allowing a person associated with the pass to access at least one restricted-access area of a building, and to a method implemented by such a pass for accessing a restricted-access area of a building. According to some embodiments, when a pass reader authorizes access to said area after reading the pass, information selected on the basis of the restricted-access area is temporarily displayed on the pass. This makes it possible to identify the carrier within the area based on the information displayed on the pass, while at the same time limiting the possibility of information being recovered through a simple glance outside the area. Overall security is thereby improved as a result, both within the area and outside it, due to the temporary nature of the display.

Electronic access pass

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PARIS, France

Nathan Reboud