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116 lines
4.1 KiB
C
116 lines
4.1 KiB
C
/*! \file rc4.h
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\brief Header file for RC4 stream cipher routines
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\author Damien Miller <djm@mindrot.org>
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\version 0.0.0
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\date 1999
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A simple implementation of the RC4 stream cipher, based on the
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description given in _Bruce Schneier's_ "Applied Cryptography"
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2nd edition.
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Copyright 1999 Damien Miller
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Permission is hereby granted, free of charge, to any person
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obtaining a copy of this software and associated documentation
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files (the "Software"), to deal in the Software without
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restriction, including without limitation the rights to use, copy,
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modify, merge, publish, distribute, sublicense, and/or sell copies
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of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
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KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
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AND NONINFRINGEMENT. IN NO EVENT SHALL DAMIEN MILLER BE LIABLE
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FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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\warning None of these functions clears its memory after use. It
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\warning is the responsability of the calling routines to ensure
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\warning that any sensitive data (keystream, key or plaintext) is
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\warning properly erased after use.
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\warning The name "RC4" is trademarked in the United States,
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\warning you may need to use "RC4 compatible" or "ARC4"
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\warning (Alleged RC4).
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*/
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/* $Id: rc4.h,v 1.1.1.1 1999/10/26 05:48:13 damien Exp $ */
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#ifndef _RC4_H
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#define _RC4_H
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#include "config.h"
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#ifndef HAVE_ARC4RANDOM
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/*! \struct rc4_t
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\brief RC4 stream cipher state object
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\var s State array
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\var i Monotonic index
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\var j Randomised index
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\warning This structure should not be accessed directly. To
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\warning initialise a rc4_t object, you should use the rc4_key()
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\warning function
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This structure holds the current state of the RC4 algorithm.
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*/
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typedef struct
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{
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unsigned int s[256];
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int i;
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int j;
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} rc4_t;
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/*! \fn void rc4_key(rc4_t *r, unsigned char *key, int len);
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\brief Set up key structure of RC4 stream cipher
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\param r pointer to RC4 structure to be seeded
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\param key pointer to buffer containing raw key
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\param len length of key
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This function set the internal state of the RC4 data structure
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pointed to by \a r using the specified \a key of length \a len.
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This function can use up to 256 bytes of key, any more are ignored.
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\warning Stream ciphers (such as RC4) can be insecure if the same
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\warning key is used repeatedly. Ensure that any key specified has
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\warning an reasonably sized Initialisation Vector component.
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*/
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void rc4_key(rc4_t *r, unsigned char *key, int len);
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/*! \fn rc4_crypt(rc4_t *r, unsigned char *plaintext, int len);
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\brief Crypt bytes using RC4 algorithm
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\param r pointer to RC4 structure to be used
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\param plaintext Pointer to bytes to encrypt
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\param len number of bytes to crypt
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This function encrypts one or more bytes (pointed to by \a plaintext)
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using the RC4 algorithm. \a r is a state structure that must be
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initialiased using the rc4_key() function prior to use.
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Since RC4 XORs each byte of plaintext with a byte of keystream,
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this function can be used for both encryption and decryption.
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*/
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void rc4_crypt(rc4_t *r, unsigned char *plaintext, int len);
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/*! \fn rc4_getbytes(rc4_t *r, unsigned char *buffer, int len);
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\brief Generate key stream using the RC4 stream cipher
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\param r pointer to RC4 structure to be used
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\param buffer pointer to buffer in which to deposit keystream
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\param len number of bytes to deposit
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This function gives access to the raw RC4 key stream. In this
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consiguration RC4 can be used as a fast, strong pseudo-random
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number generator with a very long period.
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*/
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void rc4_getbytes(rc4_t *r, unsigned char *buffer, int len);
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#endif /* !HAVE_ARC4RANDOM */
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#endif /* _RC4_H */
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