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.\" $OpenBSD: blowfish.3,v 1.18 2006/07/26 12:48:35 jmc Exp $
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.\"
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.\" Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Niels Provos.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" Manual page, using -mandoc macros
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.\"
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.Dd February 13, 1997
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.Dt BLOWFISH 3
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.Os
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.Sh NAME
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.Nm blf_key ,
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.Nm blf_enc ,
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.Nm blf_dec ,
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.Nm blf_ecb_encrypt ,
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.Nm blf_ecb_decrypt ,
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.Nm blf_cbc_encrypt ,
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.Nm blf_cbc_decrypt
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.Nd Blowfish encryption
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.Sh SYNOPSIS
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.Fd #include <blf.h>
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.Ft void
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.Fn blf_key "blf_ctx *state" "const u_int8_t *key" "u_int16_t keylen"
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.Ft void
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.Fn blf_enc "blf_ctx *state" "u_int32_t *data" "u_int16_t blocks"
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.Ft void
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.Fn blf_dec "blf_ctx *state" "u_int32_t *data" "u_int16_t blocks"
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.Ft void
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.Fn blf_ecb_encrypt "blf_ctx *state" "u_int8_t *data" "u_int32_t datalen"
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.Ft void
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.Fn blf_ecb_decrypt "blf_ctx *state" "u_int8_t *data" "u_int32_t datalen"
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.Ft void
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.Fn blf_cbc_encrypt "blf_ctx *state" "u_int8_t *iv" "u_int8_t *data" "u_int32_t datalen"
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.Ft void
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.Fn blf_cbc_decrypt "blf_ctx *state" "u_int8_t *iv" "u_int8_t *data" "u_int32_t datalen"
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.Sh DESCRIPTION
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.Em Blowfish
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is a fast unpatented block cipher designed by Bruce Schneier.
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It basically consists of a 16-round Feistel network.
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The block size is 64 bits and the maximum key size is 448 bits.
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.Pp
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The
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.Fn blf_key
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function initializes the 4 8-bit S-boxes and the 18 Subkeys with
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the hexadecimal digits of Pi.
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The key is used for further randomization.
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The first argument to
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.Fn blf_enc
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is the initialized state derived from
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.Fn blf_key .
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The stream of 32-bit words is encrypted in Electronic Codebook
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Mode (ECB) and
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.Fa blocks
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is the number of 64-bit blocks in the stream.
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.Fn blf_dec
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is used for decrypting Blowfish encrypted blocks.
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.Pp
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The functions
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.Fn blf_ecb_encrypt
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and
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.Fn blf_ecb_decrypt
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are used for encrypting and decrypting octet streams in ECB mode.
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The functions
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.Fn blf_cbc_encrypt
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and
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.Fn blf_cbc_decrypt
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are used for encrypting and decrypting octet streams in
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Cipherblock Chaining Mode (CBC).
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For these functions
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.Fa datalen
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specifies the number of octets of data to encrypt or decrypt.
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It must be a multiple of 8 (64-bit block).
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The initialisation vector
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.Fa iv
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points to an 8-byte buffer.
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.Pp
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The functions
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.Fn Blowfish_initstate ,
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.Fn Blowfish_expand0state ,
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.Fn Blowfish_expandstate ,
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.Fn Blowfish_encipher ,
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and
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.Fn Blowfish_decipher
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are used for customization of the
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.Em Blowfish
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cipher,
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for example for the blowfish password hashing function.
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.Sh SEE ALSO
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.Xr passwd 1 ,
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.Xr crypt 3 ,
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.Xr passwd 5
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.Sh AUTHORS
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.An Niels Provos Aq provos@physnet.uni-hamburg.de
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