mirror of git://anongit.mindrot.org/openssh.git
106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
|
/*! \file rc4.c
|
||
|
|
\brief Source 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.c,v 1.1.1.1 1999/10/26 05:48:13 damien Exp $ */
|
||
|
|
|
||
|
|
#include "rc4.h"
|
||
|
|
|
||
|
|
|
||
|
|
void rc4_key(rc4_t *r, unsigned char *key, int len)
|
||
|
|
{
|
||
|
|
int t;
|
||
|
|
|
||
|
|
for(r->i = 0; r->i < 256; r->i++)
|
||
|
|
r->s[r->i] = r->i;
|
||
|
|
|
||
|
|
r->j = 0;
|
||
|
|
for(r->i = 0; r->i < 256; r->i++)
|
||
|
|
{
|
||
|
|
r->j = (r->j + r->s[r->i] + key[r->i % len]) % 256;
|
||
|
|
t = r->s[r->i];
|
||
|
|
r->s[r->i] = r->s[r->j];
|
||
|
|
r->s[r->j] = t;
|
||
|
|
}
|
||
|
|
r->i = r->j = 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
void rc4_crypt(rc4_t *r, unsigned char *plaintext, int len)
|
||
|
|
{
|
||
|
|
int t;
|
||
|
|
int c;
|
||
|
|
|
||
|
|
c = 0;
|
||
|
|
while(c < len)
|
||
|
|
{
|
||
|
|
r->i = (r->i + 1) % 256;
|
||
|
|
r->j = (r->j + r->s[r->i]) % 256;
|
||
|
|
t = r->s[r->i];
|
||
|
|
r->s[r->i] = r->s[r->j];
|
||
|
|
r->s[r->j] = t;
|
||
|
|
|
||
|
|
t = (r->s[r->i] + r->s[r->j]) % 256;
|
||
|
|
|
||
|
|
plaintext[c] ^= r->s[t];
|
||
|
|
c++;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void rc4_getbytes(rc4_t *r, unsigned char *buffer, int len)
|
||
|
|
{
|
||
|
|
int t;
|
||
|
|
int c;
|
||
|
|
|
||
|
|
c = 0;
|
||
|
|
while(c < len)
|
||
|
|
{
|
||
|
|
r->i = (r->i + 1) % 256;
|
||
|
|
r->j = (r->j + r->s[r->i]) % 256;
|
||
|
|
t = r->s[r->i];
|
||
|
|
r->s[r->i] = r->s[r->j];
|
||
|
|
r->s[r->j] = t;
|
||
|
|
|
||
|
|
t = (r->s[r->i] + r->s[r->j]) % 256;
|
||
|
|
|
||
|
|
buffer[c] = r->s[t];
|
||
|
|
c++;
|
||
|
|
}
|
||
|
|
}
|