| 摘要 |
PROBLEM TO BE SOLVED: To impart an electronic signature to content data of a large data size even when a user uses a terminal device of which memory capacity is limited. SOLUTION: An electronic signature server 20 for imparting an electronic signature of the user to content data 23C generates random data from the content data 23C and transmits, to a terminal device 10, first encrypted data resulting from encrypting the random data using a user public key 23A. The terminal device 10 decrypts the first encrypted data and transmits, to the electronic signature server 20, second encrypted data resulting from encrypting the decrypted data using a user private key 13C. If data resulting from decrypting the second encrypted data using the user public key 23A are coincident with the random data generated from the content data 23C, the electronic signature server 20 makes the second encrypted data correspond to the content data 23C, thereby imparting the electronic signature of the user to the content data 23C. COPYRIGHT: (C)2008,JPO&INPIT
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