Abstract:
A variable-length block cipher apparatus and method capable of format preserving encryption are provided. An encryption device for a variable-length block cipher apparatus includes an encryption key generation unit configured to generate encryption round keys eRK0, eRK1, . . . , eRKNr using a secret key and the number of rounds Nr, and a ciphertext output unit configured to output ciphertext having a length identical to that of plaintext using the plaintext and the encryption round keys. 7. A decryption device for a variable-length block cipher apparatus includes a decryption key generation unit configured to generate decryption round keys dRK0, dRK1, . . . , dRKNr using a secret key and a number of rounds Nr, and a plaintext restoration unit configured to restore ciphertext into plaintext having a length identical to that of the ciphertext using the ciphertext and the decryption round keys.