DES data encryption standard DES is a block encryption method originally developed by IBM. It has since been certified by the U.S. government for transmission of any data that is not classified top secret. DES uses an algorithm for doing private-key encryption. The key consists of 64 bits of data, which are transformed and combined with the first 64 bits of the message to be sent. To do the encryption, the message is broken up into 64-bit blocks so that each can be combined with the key using a complex 16-step process. Though DES is fairly weak, with only one iteration, repeating it using slightly different keys can provide excellent security. See also: encryption