SIGNATURE SYSTEM, SIGNATURE METHOD, CERTIFYING APPARATUS, VERIFYING APPARATUS, CERTIFYING METHOD, VERIFYING METHOD, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To enable verification for legitimacy of signature and denial of forged signature with the identical procedure and also reduce the length of signature data. Ž

SOLUTION: A first calculating section in a certifying apparatus generates a random number r to calculate X1=grand transmits X1to a verifying apparatus. An element sharing section for certification in a certifying apparatus and an element sharing section for verification in a verifying apparatus share an element t of random G2. A second calculating section in the certifying apparatus calculates X2=e(h(m)r, t) and transmits X2to the verifying apparatus. A random number generating section for verification in the verifying apparatus generates a random number c and transmits c to the certifying apparatus. A third calculating section in the certifying apparatus calculates σ=r+cx(mod v) and transmits σ to the verifying apparatus. A verifying section in the verifying apparatus verifies whether X1×yc=gσand X2×e(s', t)c=e(h(m), t)σare held. Ž

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