| 摘要 |
PROBLEM TO BE SOLVED: To provide an encryption communication technology based on a public key encryption in which safety can be verified even when an attacker to a public key encryption selects a random function that gives random oracle. SOLUTION: A sender side device 100 generates a ciphertext so that the attacker, who can obtain the results of decryption of an arbitrarily selected ciphertext, cannot calculate partial information with regard to a message and an input value to a random function from a target ciphertext which is the ciphertext being the object of the attack, and transmits the ciphertext to a receiver side device 200. The receiver side device 200 verifies, by using a private key of the receiver side device 200, that the ciphertext received from the sender side device 100 is a legitimate ciphertext. When the verification is successful, the results of decryption of the ciphertext are output as a message text. COPYRIGHT: (C)2007,JPO&INPIT
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