Patent ID: 7603554

Claim:
An encryption communication system for secret message communication, the encryption communication system comprising an encryption transmission apparatus and an encryption reception apparatus, wherein the encryption transmission apparatus includes: a storage unit that stores one message; an encryption unit operable to perform an encryption computation on the one message a plural number of times to generate a plurality of encrypted messages from the one message, a number of encrypted messages generated from the one message by the encryption unit being equal to the number of times the encryption unit performs the encryption computation on the one message; a computation unit operable to perform a one-way operation on the one message to generate only one comparison computation value from the one message; and a transmission unit operable to transmit, to the encryption reception apparatus, the plurality of the encrypted messages and the one comparison computation value, and wherein the encryption reception apparatus includes: a reception unit operable to receive, from the encryption transmission apparatus, the plurality of the encrypted messages and the one comparison computation value; a decryption unit operable to perform a decryption computation corresponding to the encryption computation, the decryption computation being performed on each of the encrypted messages to generate a plurality of decrypted messages, and a number of decrypted messages generated by the decryption unit being equal to the number of encrypted messages generated from the one message by the encryption unit; a computation unit operable to perform the one-way operation on each of the decrypted messages to generate a plurality of decryption computation values, a number of decryption values generated by the computation unit being equal to the number of the decrypted messages generated by the decryption unit; and a judging unit operable to compare each of the decryption computation values with the one received comparison computation value, wherein (i) when at least one of the decryption computation values matches the one received comparison computation value, the judging unit outputs a decrypted message as a correct decrypted message, and (ii) when none of the decryption computation values matches the one received comparison computation value, the judging unit determines that there is a decryption error.