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78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
/* arc4.c
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*
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* Copyright (C) 2006-2012 Sawtooth Consulting Ltd.
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*
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* This file is part of CyaSSL.
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*
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* CyaSSL is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* CyaSSL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <cyassl/ctaocrypt/arc4.h>
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void Arc4SetKey(Arc4* arc4, const byte* key, word32 length)
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{
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word32 i;
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word32 keyIndex = 0, stateIndex = 0;
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arc4->x = 1;
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arc4->y = 0;
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for (i = 0; i < ARC4_STATE_SIZE; i++)
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arc4->state[i] = (byte)i;
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for (i = 0; i < ARC4_STATE_SIZE; i++) {
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word32 a = arc4->state[i];
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stateIndex += key[keyIndex] + a;
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stateIndex &= 0xFF;
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arc4->state[i] = arc4->state[stateIndex];
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arc4->state[stateIndex] = (byte)a;
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if (++keyIndex >= length)
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keyIndex = 0;
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}
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}
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static INLINE byte MakeByte(word32* x, word32* y, byte* s)
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{
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word32 a = s[*x], b;
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*y = (*y+a) & 0xff;
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b = s[*y];
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s[*x] = (byte)b;
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s[*y] = (byte)a;
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*x = (*x+1) & 0xff;
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return s[(a+b) & 0xff];
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}
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void Arc4Process(Arc4* arc4, byte* out, const byte* in, word32 length)
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{
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word32 x = arc4->x;
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word32 y = arc4->y;
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while(length--)
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*out++ = *in++ ^ MakeByte(&x, &y, arc4->state);
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arc4->x = (byte)x;
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arc4->y = (byte)y;
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}
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