| 摘要 |
PURPOSE: A method for a message added digital signature and a verifying method thereof are provided to offer an electronic document with a function of a signature written on paper, make proof of an original document writer by the electronic document, make the electronic document inform that contents of the original document are altered, and improve speed of a step for verifying the digital signature. CONSTITUTION: A Hash code for a message to be sent and a value calculated by a random number generated for each signature are multiplied(100). After the modular multiplication multiplying a multiplied value to a modular, a front part of the signature is obtained by cutting a modular multiplication result with predetermined bits(140). A rear part of the signature is found out by a function of a secrete key of a signer, the random number generated for each signature, and the front part of the signature(150). The front and the rear part of the signature, a signature verification key to verify the digital signature, and the message are transmitted(170).
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