France Telecom

Gemplus

Thomson Multimedia S.a.

Gemplus Card International

Stern, Jacques

Jacques Stern

David Naccache

Jacek A Kowalski

Henri Gilbert

David Arditti

Michel Martin

Louis Gregoire

Jean-Bernard Fischer

David M'Raihi

Mario De Vito

David Pointcheval

Antoine Joux

Serge Vaudenay

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.

Public key identification process using two hash functions

Method of cryptography with public key based on the discrete logarithm

Encryption and authentication method and circuit for synchronous smart

The present invention relates to a method of processing a digital signal of dimension k, in a so-called secure communication system, such that the digital signal (y) at output cannot be deduced from the digital signal (x) at input, consisting in dispatching the digital signal (x) to a device effecting a one-way function. The method includes the following steps:

Method for processing a digital signal in a so-called secure

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Paris, France

Jacques Stern