METHOD FOR CIPHERING AND DECIPHERING DIGITAL DATA, BASED ON AN IDENTITY, IN A MULTI-AUTHORITIES CONTEXT

摘要

In one embodiment, it is proposed a for ciphering digital data M being an element of a group _T, said group _T being part of a bilinear group of prime order p. The method can be executed by an electronic device, and is remarkable in that it comprises:applying a hash function to an identity associated to a recipient electronic device, delivering K+1 elements, each element belonging to said group , and K being an integer value greater than or equal to one;obtaining from common public parameters, shared by n trusted authorities servers, n being an integer value greater or equal to two, 2K generators of said group ;obtaining K random element(s) belonging to _p;determining K+1 elements belonging to said group via exponentiations of combinations of generators from said 2K generators, with exponents being said K random element(s), said K+1 elements being a first part of a ciphertext of said digital data M;determining a product of said digital data M with K+1 elements belonging to said group _T, each of said K+1 elements belonging to said group _T being obtained via applying a pairing function on a combination of elements of a master public key associated to one of the n trusted authorities, said K random element(s) and output of said applying a hash function, delivering a second part of said ciphertext of said digital data M.