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.\" FreeSec: libcrypt for NetBSD
.\"
.\" Copyright (c) 1994 David Burren
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 4. Neither the name of the author nor the names of other contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.\" Manual page, using -mandoc macros
.\"
.Dd March 9, 1994
.Dt CIPHER 3
.Os "FreeSec 1.0"
.Sh NAME
.Nm setkey ,
.Nm encrypt ,
.Nm des_setkey ,
.Nm des_cipher ,
.Nd DES encryption
.Sh SYNOPSIS
.Ft int
.Fn setkey "char *key"
.Ft int
.Fn encrypt "char *block" "int flag"
.Ft int
.Fn des_setkey "const char *key"
.Ft int
.Fn des_cipher "const char *in" "char *out" "long salt" "int count"
.Sh DESCRIPTION
The functions,
.Fn encrypt ,
.Fn setkey ,
.Fn des_setkey
and
.Fn des_cipher
provide access to the
.Tn DES
algorithm.
.Fn setkey
is passed a 64-byte array of binary values (numeric 0 or 1).
A 56-bit key is extracted from this array by dividing the
array into groups of 8, and ignoring the last bit in each group.
That bit is reserved for a byte parity check by DES, but is ignored
by these functions.
.Pp
The
.Fa block
argument to
.Fn encrypt
is also a 64-byte array of binary values.
If the value of
.Fa flag
is 0,
.Fa block
is encrypted otherwise it is decrypted.
The result is returned in the original array
.Fa block
after using the key specified by
.Fn setkey
to process it.
.Pp
The argument to
.Fn des_setkey
is a character array of length 8.
The least significant bit (the parity bit) in each character is ignored,
and the remaining bits are concatenated to form a 56-bit key.
The function
.Fn des_cipher
encrypts (or decrypts if
.Fa count
is negative) the 64-bits stored in the 8 characters at
.Fa in
using
.Xr abs 3
of
.Fa count
iterations of
.Tn DES
and stores the 64-bit result in the 8 characters at
.Fa out
(which may be the same as
.Fa in
).
The
.Fa salt
introduces disorder in the
.Tn DES
algorithm in one of 16777216 or 4096 possible ways
(ie. with 24 or 12 bits: if bit
.Em i
of the
.Ar salt
is set, then bits
.Em i
and
.Em i+24
are swapped in the
.Tn DES
E-box output).
.Pp
The functions
.Fn setkey ,
.Fn encrypt ,
.Fn des_setkey ,
and
.Fn des_cipher
return 0 on success and 1 on failure.
.Pp
The
.Fn setkey
and
.Fn des_setkey
functions manipulate the same key space.
.Sh SEE ALSO
.Xr login 1 ,
.Xr passwd 1 ,
.Xr crypt 3 ,
.Xr getpass 3 ,
.Xr passwd 5
.Sh HISTORY
This library (FreeSec 1.0) was developed outside the United States of America
as an unencumbered replacement for the U.S.-only NetBSD libcrypt encryption
library.
Users should be aware that this code (and programs staticly linked with it)
may not be exported from the U.S., although it apparently can be imported.
.Sh AUTHOR
David Burren <davidb@werj.com.au>
|
