Information Security and Cryptography: The Block Cipher Companion (Hardcover)

Block ciphers encrypt blocks of plaintext, messages, into blocks of ciphertext under the action of a secret key, and the process of encryption is reversed by decryption which uses the same user-supplied key.

Block ciphers are fundamental to modern cryptography, in fact they are the most widely used cryptographic primitive - useful in their own right, and in the construction of other cryptographic mechanisms.