| 摘要 |
PROBLEM TO BE SOLVED: To prevent the increase of signature information and further to judge effective the signatures of plural signers even when signing is performed any number of times. SOLUTION: A key manager part 1 generates secret keys e1-ei and decode keys d1-di and distributes them to respective signers as prescribed manner. A first signer part 2 is operated by a drafter having the secret key e1 e1 and decode key d1, enciphers an object document, for example, prepared by the drafter through the signature using the secret key and transfers it to the following signer part. Signer parts 3-5 are operated by a j-th signer having a secret key ei and decode keys d (j-1) and dj, a cryptographic sentence C (j-1) of the preceding step transferred from the signer part of the preceding step is deciphered and confirmed while using the decode key d (j-1) and the cryptographic sentence C (j-1) is enciphered by the signature using the secret key e1. |
