| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-speed processing non-repudiation signing system. SOLUTION: When a public key (D, P, k, t) and a secret key (D, l, q) are given, a verifier generates a challenge C by calculating a message ideal M of a message m when a norm N(S) of a signature (S) is k-bits or less, calculating H=(M/S)r by generating a random number r smaller than t-bits, and calculating C=BH by generating a random number ideal B of which the norm is smaller than (k-1) bits; a signer generates a response W by mapping the above challenge C on a class group C1 (D1) by using the secret key (D1, q), bringing back the mapped challenge C to the class group C1 (D), and squaring the mapped and brought-back result, and the verifier checks whether or not W=B2 holds, and when it holds, the verifier determines the signature as justified.
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