des.1

大名鼎鼎的DES加密算法

.TH DES 1  "24 March 1987"
.SH NAME
des - DES file encryption
.SH SYNOPSIS
.PP
.B des -e|-d [-h] [-k key] [-b]
.SH DESCRIPTION
.B 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.
.P
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.
.PP
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.
.PP
Except for the -h option, this command is compatible with the
.B des
command on the Sun Microsystems workstation.
.SH "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.
.SH AUTHOR
Phil Karn, KA9Q