METHOD OF CONVERTING A FIRST NUMBER TO A SECOND NUMBER

摘要

The invention relates to a method of conversion by a conversion entity of a first cipher (y) into a second cipher (y), the first cipher corresponding to the result of a symmetric probabilistic ciphering of a plaintext message element ( x) by means of a first secret matrix (M) parameterized by a random vector (a), the second cipher (y) corresponding to the result of a symmetrical probabilistic ciphering of the plaintext message element by means of a second secret matrix (M) parameterized by the random vector, characterized in that the method comprises a step of: - calculating (E22) the second cipher (y) by encrypting the first cipher using a secret conversion matrix ( M) function of the first and second secret matrices, and parameterized by the random vector (a).