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