The Free On-line Dictionary of Computing (30 December 2018):

Data Encryption Standard
DES

   (DES) The NBS's popular, standard encryption algorithm.
   It is a product cipher that operates on 64-bit blocks of
   data, using a 56-bit key.  It is defined in FIPS 46-1 (1988)
   (which supersedes FIPS 46 (1977)).  DES is identical to the
   ANSI standard Data Encryption Algorithm (DEA) defined in
   ANSI X3.92-1981.

   DES has been implemented in VLSI.  SunOS provides a des
   command which can make use of DES hardware if fitted.  Neither
   the software nor the hardware are supposed to be distributed
   outside the USA.

   Unix manual pages: des(1), des(3), des(4).

   (1994-12-06)