Cryptographic methods and devices for pseudo-random generation, encrypting data, and cryptographically hashing a message

摘要

The invention relates to the general field of digital security and more particularly cryptography. In particular it proposes a device and a method of encrypting a sequence of data. The invention also relates to a cryptographic device (1) and a cryptographic method of generating a pseudo-random data sequence (13) and their favored use in the field of digital security, in particular for encrypting and decrypting data and for cryptographically hashing messages.

主权项

1. A cryptographic method by a pseudo-random generator of generating a current value for a state vector of size k corresponding to a current iteration of a pseudo-random data sequence formed by a succession of values for the state vector generated iteratively from an initial value of the state vector, the method comprising:
obtaining, with a processing device, a current intermediate value calculated from a preceding value of the state vector generated in a previous iteration; forming, with the processing device, a permutation key by selecting d bits from a first intermediate vector of size k, wherein d is less than or equal to k and the first intermediate vector is formed from the preceding value of the state vector in which a section has been replaced by the current intermediate value; determining, with the processing device, d permutations, each of size k1, as a function at least of the value of a respective associated bit of the permutation key; successively applying, with the processing device, each of the permutations to a provisional vector of size k1 to determine a result vector, wherein k1 is greater than or equal to k and the provisional vector includes the first intermediate vector; and determining, with the processing device, the current value of the state vector from at least one section of said result vector.