126 lines
4 KiB
Groff
126 lines
4 KiB
Groff
.\" $OpenBSD: RC4.3,v 1.8 2020/03/29 17:05:02 schwarze Exp $
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.\" OpenSSL 99d63d46 Oct 26 13:56:48 2016 -0400
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.\"
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.\" This file was written by Ulf Moeller <ulf@openssl.org>.
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.\" Copyright (c) 2000 The OpenSSL Project. 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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.\"
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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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.\"
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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
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" 3. All advertising materials mentioning features or use of this
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.\" software must display the following acknowledgment:
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.\" "This product includes software developed by the OpenSSL Project
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.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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.\"
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.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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.\" endorse or promote products derived from this software without
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.\" prior written permission. For written permission, please contact
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.\" openssl-core@openssl.org.
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.\"
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.\" 5. Products derived from this software may not be called "OpenSSL"
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.\" nor may "OpenSSL" appear in their names without prior written
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.\" permission of the OpenSSL Project.
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.\"
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.\" 6. Redistributions of any form whatsoever must retain the following
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.\" acknowledgment:
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.\" "This product includes software developed by the OpenSSL Project
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.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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.\" OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd $Mdocdate: March 29 2020 $
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.Dt RC4 3
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.Os
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.Sh NAME
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.Nm RC4_set_key ,
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.Nm RC4
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.Nd RC4 encryption
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.Sh SYNOPSIS
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.In openssl/rc4.h
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.Ft void
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.Fo RC4_set_key
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.Fa "RC4_KEY *key"
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.Fa "int len"
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.Fa "const unsigned char *data"
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.Fc
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.Ft void
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.Fo RC4
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.Fa "RC4_KEY *key"
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.Fa "unsigned long len"
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.Fa "const unsigned char *indata"
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.Fa "unsigned char *outdata"
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.Fc
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.Sh DESCRIPTION
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This library implements the alleged RC4 cipher, which is described for
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example in
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.Qq Applied Cryptography .
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It is believed to be compatible with RC4[TM], a proprietary cipher of
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RSA Security Inc.
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.Pp
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RC4 is a stream cipher with variable key length.
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Typically, 128-bit (16-byte) keys are used for strong encryption, but
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shorter insecure key sizes have been widely used due to export
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restrictions.
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.Pp
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RC4 consists of a key setup phase and the actual encryption or
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decryption phase.
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.Pp
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.Fn RC4_set_key
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sets up the
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.Vt RC4_KEY
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.Fa key
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using the
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.Fa len
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bytes long key at
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.Fa data .
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.Pp
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.Fn RC4
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encrypts or decrypts the
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.Fa len
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bytes of data at
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.Fa indata
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using
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.Fa key
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and places the result at
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.Fa outdata .
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Repeated
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.Fn RC4
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calls with the same
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.Fa key
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yield a continuous key stream.
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.Pp
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Since RC4 is a stream cipher (the input is XOR'ed with a pseudo-random
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key stream to produce the output), decryption uses the same function
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calls as encryption.
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.Sh SEE ALSO
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.Xr blowfish 3 ,
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.Xr EVP_EncryptInit 3 ,
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.Xr EVP_rc4 3
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.Sh HISTORY
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.Fn RC4_set_key
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and
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.Fn RC4
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appeared in SSLeay 0.4 or earlier and have been available since
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.Ox 2.4 .
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.Sh BUGS
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This cipher is broken and should no longer be used.
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