A cipher that transforms a string of input bits of fixed length into a string of output bits of fixed length.
An encryption method that processes the input stream as groups of bytes that are fixed in size, typically 64, 128 or 256 bits long. The state of a block cipher is reset before processing each block. The DES and AES algorithms are examples of block ciphers (see DES and AES). Contrast with stream cipher.
Beginning with sections on the basic cryptographic theory and historical cyphers, the volume cover such topics as public key encryption, block cyphers, hash functions and random numbers and stream cyphers.