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DES1.DOC
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1987-12-22
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DES(1) 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 interpreted.
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 characters; 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