Data Encryption Standard [http://www.cacr.math.uwaterloo.ca/hac/]

See [DES in Tcl], [tcllib]

Man page for Unix des command:

User Commands                                              DES(1)

NAME
     des - DES file encryption

SYNOPSIS
     des -e|-d [-h] [-k key] [-b]

DESCRIPTION
     des is a filter that encrypts or decrypts standard input  to
     standard  output  with  the  Data Encryption Standard (DES).
     Either -e (encrypt) or -d (decrypt) must  be  specified.  If
     the  key is not given on the command line with the -k option
     the command will prompt for it twice, suppressing  echo  and
     comparing the two responses to guard against mistyping.

     The -h flag controls how the key  string  is  to  be  inter-
     preted.   Without  the  -h flag, the key is an ASCII string.
     Since DES ignores the low order bit of each  key  byte,  the
     high  order  bit  is  set for odd parity, thus retaining the
     information contained in the low order bit.  If the -h  flag
     is  set, the key string is interpreted as 16 hex/ASCII char-
     acters; the low order bit of each byte is again  ignored  as
     per the DES algorithm.  This allows the use of any arbitrary
     56-bit key, including bytes representing control  characters
     that could not be typed if the -h option were not used.

     By default, DES Cipher Block Chaining (CBC)  mode  is  used,
     with  an  initial vector (IV) of all zeros; if the -b option
     is specified,  Electronic  Code  Book  (ECB)  mode  is  used
     instead.

     Except for the -h option, this command  is  compatible  with
     the des command on the Sun Microsystems workstation.

SEE ALSO
     Sun Microsystems DES(1)  manual  page,  which  describes  in
     detail  how  the  length  of the file is encoded in the last
     block of ciphertext.

AUTHOR
     Phil Karn, KA9Q

        Last change: 24 March 1987                   1


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