Abstract: The present invention relates to a cryptographic method of protection against fraud in transactions between an application (1) and an electronic chip (2) of a user.

Abstract: The present invention relates to a method of protecting an electronic chip (1) of a user against fraud in transactions between an application (2) and the electronic chip (1).

Abstract: This invention relates to an authentication process with an access control and/or payment system that maintains anonymity of the customer towards a third party, characterized in that a single-directional authentication protocol is used to send an authentication sequence that is completely different for each transaction, so that it is impossible for a third party to determine the identity of this customer, or even to determine which transactions are sent by a particular customer.

Abstract: Communication process with key encryption escrow and recovery systems.

Abstract: A process for the identification of a claimant by a verifier. The process is of the public key type, where the public exponent is equal to 3. The claimant draws at random a first exponent .alpha., calculates r=g.sup..alpha. mod n and transmits R=r.sup.3. The verifier draws at random a second exponent .beta., calculates t=g.sup..beta. mod n, calculates T=t.sup.3 mod n and h=H.sub.1 (Z), where H.sub.1 is a hash function, and calculates Z=R.sup.3 mod n. The verifier transmits to the claimant the numbers T and h. The claimant calculates Y=T.sup..alpha. mod n, verifies the result H.sub.1 (Y), calculates H=H.sub.2 (Y), where H.sub.2 is another hash function, calculates z=rS mod n, and transmits z and H. The claimant also has a secret number S equal to the modulo n cubic root of a number I deduced from its identity so that the number S verifies S.sup.3 =I mod n. The verifier verifies that H received is equal to H.sub.2 (Z) and that z.sup.3 is equal to RI mod n.

Abstract: According to the invention, the secret key of the claimant is constituted by k numbers s.sub.1, s.sub.2, . . . , s.sub.k with a low public exponent. The verifier draws k numbers a.sub.1, a.sub.2, . . . , a.sub.k in which the number of non-zero a.sub.i is below a given number p. The claimant or signatory calculates an answer involving an exponential product of form s.sub.i.sup.a.sbsp.1 with i between 1 and k. The verifier calculates another exponential product of form v.sub.i.sup.a.sbsp.1, where the v.sub.i are numbers corresponding to the public key of the claimant or signatory. The verifier then verifies that the result obtained is correct. The choice of the public exponent and the limitation on p make it possible to reduce the number of secrets for equal security and an approximately equal number of multiplications.

Abstract: A cryptographic process is for protection against fraud. An allocation of a secret key K is made to a card and to an application and an input value R is defined. The card and application calculate the modulo 2 scalar product of binary vectors constituted by words of R and words of K. The application checks whether the result obtained by the card is in agreement with its own result. An exemplary application is low cost cards.

Abstract: A process for controlling communication between a first and a second smart card using key-based cryptography is provided. In the disclosed process, a first identity code is stored in the first smart card and a second identity code is stored in the second smart card. The smart cards are customized by writing into each of the smart cards an identical group secret key and respective algorithms for processing the identical group secret key and the first and second identity codes stored in the first and second smart cards, respectively. The smart cards are used by transmitting the first identity code to the second smart card, transmitting the second identity code to the first smart card, and calculating using the respective processing algorithms stored in the smart cards, first and second session keys for the first and second smart cards, respectively.

Abstract: An electronic device for processing digital data has an input for receiving data to be processed and processor means suitable for transforming the input data in non-falsifiable manner into a result condensed data block. The processor means tools that are simple and fast, such as arrays and logic operators, to provide an elementary anti-collision operation for use in condensing the digital data.