| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a system which can delete electronic mail having been sent before the recipient reads it. SOLUTION: A sender terminal A(1) sends 1st ciphered electronic mail generated by ciphering electronic mail to be sent by using a transmission-side secret key and a 1st ciphered secret key generated by deciphering the transmission-side secret key by using a reception-side open key through network, and a reception- side mail server M2(4) receives and stores them in a specified memory. The sender terminal A(1) sends 2nd ciphered electronic mail and a 2nd ciphered secret key which are similarly generated after signing them with the reception- side open key, and the reception-side mail server M2(4) deciphers them with a reception-side secret key and makes comparison with the 1st ciphered electronic mail and the 1st ciphered secret key to delete the 1st ciphered electronic mail and the 1st ciphered secret key which are stored when they match each other. COPYRIGHT: (C)2003,JPO
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