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

摘要

PPROBLEM 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. PSOLUTION: In a signature generating apparatus, at least a private key (x) ((x) is an integer of 0 to p-1) and public keys gSB1/SB, gSB2/SB, (w), (u), (v) (w=gSB2/SBSPx/SP, (u) and (v) form the origin of G2) and a document (m) is acquired. Random numbers (r), (s) are then generated, σ=ägSB1/SBSPm/SPϕ(u)ϕ(v)SPs/SP}SP1/(x+r)/SPis 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 gSB1/SB, gSB2/SB, (w), (u), (v) of the signature generating apparatus are acquired. Then it is confirmed that e(σ, wgSB2/SBSPr/SP)=e(gSB1/SB, gSB2/SBSPm/SPuvSPs/SP) 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. PCOPYRIGHT: (C)2007,JPO&INPIT