Apparatus for encryption and method using the same

An encryption method and an encryption apparatus are provided to increase an encryption speed by parallel-processing plural ciphertexts simultaneously. An encryption apparatus includes a first block cipher(110), a parallel processor(120), and a converter(170). The first block cipher block-encrypts an N bit input to an M bit output, where M is greater than N. The parallel processor divides the M bit output to at least two N bit inputs, and block-encrypts the respective N bit inputs into an M bit output by using a parallel processing using plural second block ciphers. The number of the second block ciphers corresponds to the number of the N bit inputs. The converter converts a plaintext to a ciphertext based on the block-encrypted M bit output.