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1991-05-06
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DES 1 "24 March 1987"
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