| 摘要 |
PROBLEM TO BE SOLVED: To provide a forward secure encryption system for further improving security while maintaining simplicity of update processing of a decryption key. SOLUTION: A reception terminal 20 includes: an update section 22 for carrying out updates such as updating an FSE decryption key using the FSE decryption key before update (internal update) and updating an FSE decryption key using a master key stored in an external auxiliary unit 40 (external update); and a decryption section 23 that decrypts the encryption text resulting from encrypting a plain text by using the FSE pubic key and time and the PKE public key through the use of the FSE decryption key and the PKE decryption key corresponding to the encrypted time. COPYRIGHT: (C)2007,JPO&INPIT
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