Idemia France

Oberthur Technologies

Guillaume Barbu

Christophe Giraud

Luk Bettale

Nicolas Debande

Alberto Battistello

Franck Rondepierre

Nathan Reboud

Thomas Chabrier

Philippe Andouard

Alberto Batistello

Soline Renner

Laurent Castelnovi

Sarah Lopez

Olivier Chambley

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

A cryptographic processing method comprises the following steps:

Cryptographic processing method, related electronic device and computer program

Disclosed is a method for writing in a non-volatile memory of an electronic entity, the method including the following steps: determining an operational state of the electronic entity; writing a first datum in a first area of the non-volatile memory in case of abnormal operation; writing a second datum in a second area of the non-volatile memory in case of normal operation. The method includes a step for randomly determining a location for the second area from among a plurality of locations for the second area, the writing of the datum in the second area being carried out in the determined location. Also disclosed is a related electronic entity.

Method for writing in a non-volatile memory of an electronic entity, and related electronic entity

A method of testing security of an electronic device against a combination of a side-channel attack and a fault-injection attack implemented during a method of cryptographic processing that includes: delivering a message signature based on a secret parameter and implementing a recombination of at least two intermediate values according to the Chinese remainder theorem; and verifying the signature on the basis of at least one public exponent. The method of testing includes: transmitting a plurality of messages to be signed by said electronic device; disturbing each message, including modifying the message by inserting an identical error for each message, before executing a step of determining one of the intermediate values; and analyzing physical measurements, obtained during the step of verifying the signature as a function of the message to be signed, the identical error for each message, and an assumption of a value of part of the secret parameter.

Method for testing the security of an electronic device against an attack, and electronic device implementing countermeasures

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Colombes, France

Guillaume Barbu