Abstract: The invention concerns a method which consists in operating a key generation in an electronic component for a specific cryptographic algorithm; storing in the electronic component a prime number P and generating at least a secret prime number. In one step (a) randomly selecting (11) two integers p1? et p2? the sum of which is equal to a number p?; in a step (b) determining (12) whether the number p? is a prime number, on the basis of a combination of the prime number stored P with the numbers p1? et p2?, so as to maintain said number p? secret; in a third step (c), if the number p? is determined to be a prime number, storing (14) the numbers p1? et p2? in the electronic component; otherwise repeating steps (a) and (b).

Abstract: A method of exchanging data between a data processing system and an electronic entity, characterized by the following steps: the electronic entity sending the data processing system a certificate (CASD_CERT) associating an identifier of the electronic entity with a public key (CASD_PK) associated with a secret key (CASD_SK) stored in the electronic entity in a set of reserved keys associated with a first security domain; the data processing system verifying the association of the identifier and the public key (CASD_PK) via the certificate (CASD_CERT); and an application of the electronic entity separate from the first security domain and the data processing system exchanging data encrypted by the public key (CASD_PK) or signed by the first security domain by the secret key (CASD_SK) stored in the electronic entity.

Abstract: A cryptographic calculation is carried out in an electronic component according to a specific cryptographic algorithm including at least one specified non-linear operation on blocks of data of k bits, k being a whole number of more than 2. Several blocks of masked intermediate data of j bits (b?m1,c?m2, ??n) are generated from an initial block of data of k bits (a), j being a whole number that is smaller than k. Then a non-linear operation S is applied to at least one of the masked intermediate data blocks of j bits (??n) with the aid of a substitution table (106) with 2 inputs producing a modified data block of j bits (S(?)?n?). The modified data block of j bits and some, at least the masked intermediate data blocks of j bits are combined to form a result block of k bits (a?) corresponding to the initial data block of k bits by means of a transformation including the specified non linear operation.

Abstract: In an RF label identification system comprising a label reader and a plurality of labels, a unique and secret identifier being associated with each label, a first random number is sent from a label to the reader. A second random number is then sent from the reader to the label. In the RF label, a value of the encrypted identifier is then obtained by generating third and fourth random numbers in accordance with a probabilistic rule, by transforming the first and second random numbers in accordance with a determined function and by combining the identifier with the first and second random numbers, with the first and second transformed numbers and with the third and fourth random numbers. The value of the encrypted identifier is sent to the reader. After N repetitions of the above process, the reader identifies the RF label as a function of the N values of the encrypted identifier received, of the determined function, of the N first and second random numbers and of the probabilistic rule.

Abstract: The method of protecting an algorithm that can be decomposed into the form of initial polynomials (Pi) of at least two variables and of degree not less than two, comprises the steps of making combined polynomials (Qk) each obtained from at least two initial polynomials (Pi, Pi+1), and of storing the combined polynomials (Qk) in the form of a configuration file in a memory (3) associated with a processor unit (4).