esp-idf/components/lwip/netif/ppp/polarssl/arc4.c

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2016-08-17 11:08:22 -04:00
/*
* An implementation of the ARCFOUR algorithm
*
* Based on XySSL: Copyright (C) 2006-2008 Christophe Devine
*
* Copyright (C) 2009 Paul Bakker <polarssl_maintainer at polarssl dot org>
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the names of PolarSSL or XySSL nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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 COPYRIGHT
* OWNER OR CONTRIBUTORS 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.
*/
/*
* The ARCFOUR algorithm was publicly disclosed on 94/09.
*
* http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
*/
#include "lwip/opt.h"
#if PPP_SUPPORT && LWIP_INCLUDED_POLARSSL_ARC4
#include "netif/ppp/polarssl/arc4.h"
/*
* ARC4 key schedule
*/
void arc4_setup( arc4_context *ctx, unsigned char *key, int keylen )
{
int i, j, k, a;
unsigned char *m;
ctx->x = 0;
ctx->y = 0;
m = ctx->m;
for( i = 0; i < 256; i++ )
m[i] = (unsigned char) i;
j = k = 0;
for( i = 0; i < 256; i++, k++ )
{
if( k >= keylen ) k = 0;
a = m[i];
j = ( j + a + key[k] ) & 0xFF;
m[i] = m[j];
m[j] = (unsigned char) a;
}
}
/*
* ARC4 cipher function
*/
void arc4_crypt( arc4_context *ctx, unsigned char *buf, int buflen )
{
int i, x, y, a, b;
unsigned char *m;
x = ctx->x;
y = ctx->y;
m = ctx->m;
for( i = 0; i < buflen; i++ )
{
x = ( x + 1 ) & 0xFF; a = m[x];
y = ( y + a ) & 0xFF; b = m[y];
m[x] = (unsigned char) b;
m[y] = (unsigned char) a;
buf[i] = (unsigned char)
( buf[i] ^ m[(unsigned char)( a + b )] );
}
ctx->x = x;
ctx->y = y;
}
#endif /* PPP_SUPPORT && LWIP_INCLUDED_POLARSSL_DES */