DES

Data Encryption Standard provides a complete description of a mathematical algorithm for encrypting (enciphering) and decrypting (deciphering) binary coded information. When data is encrypted, it is converted to an unintelligible format called cipher. When cipher is decrypted, the data is converted back to its original format called plaintext. The algorithm described in this standard specifies both enciphering and deciphering operations which are based on a binary number called a key.