France Telecom

Orange

Côme Berbain

Henri Gilbert

Olivier Billet

Jacques Patarin

A method of generating a pseudorandom sequence of terms belonging to a finite body K of cardinal q&#x2267;2 intended to be used in a cryptographic procedure, said method comprising the iterative calculation, from an initialization n-tuple X=(X, X, . . . , X), where n&#x2267;2, of elements of K, of n-tuples X=(X, X, . . . , X) of elements of K (where i=1, 2, . . . ), each n-tuple Xbeing obtained on iteration number i in a predetermined manner at least from certain components Yof an m-tuple Y=(Y, Y, . . . , Y), where m&#x2267;n, of elements of K and the terms of said pseudorandom sequence being extracted in a predetermined manner from the n-tuples X and/or the m-tuples Y. For at least one value of i, among said components Yof the m-tuple Ythat are used to obtain the multiplet X, at least E(n/2) of them are each represented by a predetermined second degree polynomial function, with coefficients in K, of the components of the n-tuple X.

Method and device for generating a pseudorandom sequence

The invention relates to a secure communication between an electronic label (A) and a reader (B), in particular for the authentication of the label by the reader, in which: the reader () transmits at least one datum (Ch) to the label, the label calculates a combination comprising at least the datum from the reader (Ch)) and a secret (S) specific to the label, and the label communicates () the result (C(S, Ch)) of the combination to the reader (B) for verification purposes. The aforementioned combination (C(S, Ch)) is preferably calculated using a current secret value (S) delivered by a pseudo-random number generator (). The reader (B) is also provided with a homologous pseudo-random generator.

Secure communication between an electronic label and a reader

The invention relates to a method of generating a pseudorandom string of terms belonging to a finite body K of cardinal q&#x2267;2 intended to be used in a cryptography procedure, said method comprising the iterative calculation of a system (&#x393;) of m polynomials with n variables belonging to the finite body K. According to the invention, the coefficients of these m polynomials are regenerated at each iteration. The invention also relates to pseudorandom string generator intended to implement this method.

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Montrouge, France

Côme Berbain