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.\" $OpenBSD: blowfish.3,v 1.2 1998/08/10 18:40:58 provos Exp $
.\" Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
.\" 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.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by Niels Provos.
.\" 4. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
.\"
.\" Manual page, using -mandoc macros
.\"
.Dd February 13, 1997
.Dt BLOWFISH 3
.Os "OpenBSD 2.0"
.Sh NAME
.Nm blf_key,
.Nm blf_enc,
.Nm blf_dec
.Nd Blowfish encryption
.Sh SYNOPSIS
.Fd #include <blf.h>
.Ft void
.Fn blf_key "blf_ctx *state" "const u_int8_t *key" "u_int16_t keylen"
.Ft void
.Fn blf_enc "blf_ctx *state" "u_int32_t *data" "u_int16_t datalen"
.Ft void
.Fn blf_dec "blf_ctx *state" "u_int32_t *data" "u_int16_t datalen"
.Ft void
.Fn blf_ecb_encrypt "blf_ctx *state" "u_int8_t *data" "u_int32_t datalen"
.Ft void
.Fn blf_ecb_decrypt "blf_ctx *state" "u_int8_t *data" "u_int32_t datalen"
.Ft void
.Fn blf_cbc_encrypt "blf_ctx *state" "u_int8_t *iv" "u_int8_t *data" "u_int32_t datalen"
.Ft void
.Fn blf_cbc_decrypt "blf_ctx *state" "u_int8_t *iv" "u_int8_t *data" "u_int32_t datalen"
.Sh DESCRIPTION
.Pa Blowfish
is a fast unpatented block cipher designed by Bruce Schneier.
It basically consists of a 16 times iterated Feistel network.
The block size is 64 bit and the key size is maximal 448 bit.
.Pp
The
.Fn blf_key
function initializes the 4 8bit S-boxes and the 18 Subkeys with
the hexadecimal digits of Pi. The key is used for further randomization.
The first argument to
.Fn blf_enc
is the initalized state derived from
.Fn blf_key .
The stream of 32-bit words is encrypted in Electronic Codebook
Mode (ECB) and
.Pa datalen
must be even.
.Fn blf_dec
is used for decrypting Blowfish encrypted blocks.
.Pp
The functions
.Fn blf_ecb_encrypt
and
.Fn blf_ecb_decrypt
are used for encrypting and decrypting octet streams in ECB mode.
The functions
.Fn blf_cbc_encrypt
and
.Fn blf_cbc_decrypt
are used for encrypting and decrypting octet streams in
Cipherblock Chaining Mode (CBC).
.Pp
The functions
.Fn Blowfish_initstate ,
.Fn Blowfish_expand0state ,
.Fn Blowfish_expandstate ,
.Fn Blowfish_encipher
and
.Fn Blowfish_decipher
are used for customization of the
.Pa Blowfish
cipher, e.g. for the blowfish password hashing function.
.Sh SEE ALSO
.Xr crypt 3 ,
.Xr passwd 1 ,
.Xr passwd 5
.Sh AUTHOR
Niels Provos <provos@physnet.uni-hamburg.de>
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