(or Data Encryption Standard), a (symmetric) block cipher using a 64 bit block size, with keys of size 56 bit, the standard US block cipher from 1976 to 2001.

DES is based on a Feistel network, with a Feistel function composed on expansion (from 32 bit to 48), key-mixing (with a 48 bit subkey), S-boxes and finally a permutation of the 32 bit output.

DES is now considered insecure due to its small key size which allows brute-force attacks.

DES, the Data Encryption Standard, was the standard US block cypher from 1976 until AES came out in 2001. It was delisted in 2004 and withdrawn as a national standard in 2005.