Patent ID: 7155610

Claim:
A cryptocommunication system including a transmission apparatus and a reception apparatus, wherein: said transmission apparatus is operable to encrypt plaintext to generate ciphertext, perform a one-way operation on the plaintext to generate a first value, and transmit the ciphertext and the first value to said reception apparatus; said reception apparatus is operable to receive the ciphertext and the first value, decrypt the ciphertext to generate decrypted text, perform the one-way operation on the decrypted text to generate a second value, and judge that the decrypted text matches the plaintext when the second value and the first value match; said transmission apparatus comprises first generating means for generating first additional information, first operation means for performing an invertible bit-connecting operation on the plaintext and the first additional information to generate connected information, encrypting means for encrypting the connected information according to an encryption algorithm so as to generate the ciphertext, and transmitting means for transmitting the ciphertext; and said reception apparatus comprises receiving means for receiving the ciphertext transmitted from said transmitting means, second generating means for generating second additional information which is identical to the first additional information generated by said first generating means, decrypting means for decrypting the ciphertext according to a decryption algorithm, which is an inverse-conversion of the encryption algorithm, so as to generate decrypted connected information, and second operation means for performing an inverse operation of the invertible bit-connecting operation on the decrypted connected information and the second additional information so as to generate the decrypted text.