101 lines
3 KiB
C
101 lines
3 KiB
C
/*
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* An implementation of the ARCFOUR algorithm
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*
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* Based on XySSL: Copyright (C) 2006-2008 Christophe Devine
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*
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* Copyright (C) 2009 Paul Bakker <polarssl_maintainer at polarssl dot org>
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*
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* 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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* * 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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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the names of PolarSSL or XySSL nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* The ARCFOUR algorithm was publicly disclosed on 94/09.
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*
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* http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
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*/
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#include "lwip/opt.h"
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#if PPP_SUPPORT && LWIP_INCLUDED_POLARSSL_ARC4
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#include "netif/ppp/polarssl/arc4.h"
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/*
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* ARC4 key schedule
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*/
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void arc4_setup( arc4_context *ctx, unsigned char *key, int keylen )
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{
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int i, j, k, a;
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unsigned char *m;
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ctx->x = 0;
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ctx->y = 0;
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m = ctx->m;
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for( i = 0; i < 256; i++ )
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m[i] = (unsigned char) i;
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j = k = 0;
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for( i = 0; i < 256; i++, k++ )
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{
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if( k >= keylen ) k = 0;
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a = m[i];
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j = ( j + a + key[k] ) & 0xFF;
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m[i] = m[j];
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m[j] = (unsigned char) a;
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}
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}
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/*
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* ARC4 cipher function
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*/
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void arc4_crypt( arc4_context *ctx, unsigned char *buf, int buflen )
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{
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int i, x, y, a, b;
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unsigned char *m;
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x = ctx->x;
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y = ctx->y;
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m = ctx->m;
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for( i = 0; i < buflen; i++ )
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{
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x = ( x + 1 ) & 0xFF; a = m[x];
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y = ( y + a ) & 0xFF; b = m[y];
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m[x] = (unsigned char) b;
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m[y] = (unsigned char) a;
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buf[i] = (unsigned char)
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( buf[i] ^ m[(unsigned char)( a + b )] );
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}
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ctx->x = x;
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ctx->y = y;
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}
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#endif /* PPP_SUPPORT && LWIP_INCLUDED_POLARSSL_DES */
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