130 lines
3.6 KiB
C
130 lines
3.6 KiB
C
/**
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* @file arc4.c
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* @version $Format:%h%d$
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*
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* ARC4 stream cipher implementation.
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*/
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/*
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* Copyright (c) 2013-2017 Rambus Inc.
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* Copyright (c) PeerSec Networks, 2002-2011
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* All Rights Reserved
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*
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* The latest version of this code is available at http://www.matrixssl.org
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*
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* This software is open source; 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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* This General Public License does NOT permit incorporating this software
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* into proprietary programs. If you are unable to comply with the GPL, a
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* commercial license for this software may be purchased from Rambus at
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* http://www.rambus.com/
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*
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* This program is distributed in WITHOUT ANY WARRANTY; without even the
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* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the 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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* http://www.gnu.org/copyleft/gpl.html
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*/
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/******************************************************************************/
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#include "../cryptoImpl.h"
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#ifdef USE_MATRIX_ARC4
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/******************************************************************************/
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/*
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SECURITY
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Some accounts, such as O'Reilly's Secure Programming Cookbook say that no
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more than 2^30 bytes should be processed without rekeying, so we
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enforce that limit here. FYI, this is equal to 1GB of data transferred.
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*/
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# define ARC4_MAX_BYTES 0x40000000
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/******************************************************************************/
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/*
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*/
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int32_t psArc4Init(psArc4_t *arc4, const unsigned char *key, uint8_t keylen)
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{
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unsigned char index1, index2, tmp, *state;
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short counter;
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arc4->byteCount = 0;
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state = &arc4->state[0];
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for (counter = 0; counter < 256; counter++)
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{
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state[counter] = (unsigned char) counter;
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}
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arc4->x = 0;
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arc4->y = 0;
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index1 = 0;
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index2 = 0;
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for (counter = 0; counter < 256; counter++)
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{
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index2 = (key[index1] + state[counter] + index2) & 0xff;
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tmp = state[counter];
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state[counter] = state[index2];
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state[index2] = tmp;
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index1 = (index1 + 1) % keylen;
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}
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return PS_SUCCESS;
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}
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/******************************************************************************/
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void psArc4(psArc4_t *arc4, const unsigned char *in,
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unsigned char *out, uint32_t len)
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{
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unsigned char x, y, *state, xorIndex, tmp;
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uint32_t counter;
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arc4->byteCount += len;
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if (arc4->byteCount > ARC4_MAX_BYTES)
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{
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psTraceCrypto("ARC4 byteCount overrun\n");
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psAssert(arc4->byteCount <= ARC4_MAX_BYTES);
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memzero_s(arc4, sizeof(psArc4_t));
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return;
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}
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x = arc4->x;
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y = arc4->y;
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state = &arc4->state[0];
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for (counter = 0; counter < len; counter++)
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{
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x = (x + 1) & 0xff;
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y = (state[x] + y) & 0xff;
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tmp = state[x];
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state[x] = state[y];
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state[y] = tmp;
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xorIndex = (state[x] + state[y]) & 0xff;
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tmp = in[counter];
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tmp ^= state[xorIndex];
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out[counter] = tmp;
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}
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arc4->x = x;
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arc4->y = y;
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}
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void psArc4Clear(psArc4_t *arc4)
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{
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memzero_s(arc4, sizeof(psArc4_t));
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}
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#endif /* USE_MATRIX_ARC4 */
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/******************************************************************************/
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