Digital signature method, digital signature generation method, digital signature verification method, system, device, program and recording medium using the method

摘要

PROBLEM TO BE SOLVED: To provide a signature system available for other types of signatures (group signatures or blind signatures), the signature system being one that does not use hash functions.;SOLUTION: In a signature generating apparatus, at least a private key (x) ((x) is an integer of 0 to p-1) and public keys g₁, g₂, (w), (u), (v) (w=g₂^x, (u) and (v) form the origin of G2) and a document (m) is acquired. Random numbers (r), (s) are then generated, σ={g₁^mϕ(u)ϕ(v)^s}^1/(x+r) is computed, and a signature (σ, r, s) and the document (m) are transmitted to a signature verifying apparatus. In the signature verifying apparatus, the signature (σ, r, s) and the document (m) are received, and the public keys g₁, g₂, (w), (u), (v) of the signature generating apparatus are acquired. Then it is confirmed that e(σ, wg₂^r)=e(g₁, g₂^muv^s) is established; and if it is true, the signature is decided as being valid, but if it is false, the signature is decided as being invalid.;COPYRIGHT: (C)2007,JPO&INPIT