DIGITAL SIGNATURE METHOD, DIGITAL SIGNATURE GENERATION METHOD, DIGITAL SIGNATURE VERIFYING METHOD, SYSTEM, APPARATUS AND PROGRAM USING THE METHODS, AND RECORDING MEDIUM

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=g2x, (u) and (v) form the origin of G2) and a document (m) is acquired. Random numbers (r), (s) are then generated,σ=äg1mϕ(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, wg2r)=e(g1, g2muvs) 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