lucifer

Lucifer is the first encryption method that uses block ciphers. It has been considered the official standard algorithm since 1977. Lucifer is a symmetric algorithm and uses a key length of 128 bits, eight of which are for parity checking.

Generally, block ciphers divide the plaintext into data blocks of equal size, which are then ciphered with the same key.

In Lucifer, the data blocks are divided into two equal halves, each of which is encrypted separately with an encryption key, which in turn depends on the function of the pass. The two halves of the data blocks are then XORed together. This procedure changes with each new pass.