Patent ID: 11870913
Assignee: THALES DIS FRANCE SAS
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 2:
3. The method of claim 1, where an elliptic curve for generating said digitial signature is defined by elliptic curve domain parameters (p,a, b, G, n, h) with p a prime number specifying an underlying field Fp, a and b the coefficients of a Weierstrass equation, G a base point in E(Fp), n the order of G in E(Fp), h the cofactor of G in E(Fp),
wherein:
the private element is a random or pseudo-random number k chosen from {1, . . . n},
the public element is equal to Q=[k]G, [k]G being the scalar multiplication of the base point G by the private element k,
the first part of the digital signature (r) is determined from the x-coordinate of the public element Q in the elliptic curve defined by the elliptic curve domain parameters, and wherein, t being an predetermined integer:
said private element parts protected with an homomorphic encryption are equal to Eski(ki) with 1≤i≤t, skj being a secret homomorphic key, Eak(x) being a homomorphic encryption of x using a secret homomorphic key sk, and said public element parts are equal to [ki]G with 1≤i≤t.