ENCRYPTION SYSTEM, ENCRYPTION DEVICE, DECRYPTION DEVICE AND ENCRYPTION METHOD

摘要

PROBLEM TO BE SOLVED: To reduce the number of computations of a substitution computation f.SOLUTION: An encryption system of the present invention includes an encryption device and a decryption device. The encryption device is configured to divide additional authentication data and a message and repeat an exclusive OR. The decryption device is configured to divide the additional authentication data and a ciphertext and repeat the exclusive OR. In a computation of the exclusive OR with respect to the divided additional authentication data, the encryption device and the decryption device are configured to compute the exclusive OR in an entire state including a capacity part by making a computation result with respect to the capacity part unknown.SELECTED DRAWING: Figure 5