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