97a619cf17
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@13640 ec53bebd-3082-4978-b11e-865c3cabbd6b
83 lines
2.5 KiB
C
83 lines
2.5 KiB
C
/*
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* Copyright (c) 2004 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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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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* 1. 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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*
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* 2. 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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*
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* 3. Neither the name of the Institute 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 INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/* implemented from description in draft-kaukonen-cipher-arcfour-03.txt */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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RCSID("$Id$");
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#endif
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#include <rc4.h>
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#define SWAP(k,x,y) \
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{ unsigned int _t; \
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_t = k->state[x]; \
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k->state[x] = k->state[y]; \
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k->state[y] = _t; \
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}
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void
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RC4_set_key(RC4_KEY *key, const int len, unsigned char *data)
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{
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int i, j;
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for (i = 0; i < 256; i++)
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key->state[i] = i;
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for (i = 0, j = 0; i < 256; i++) {
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j = (j + key->state[i] + data[i % len]) % 256;
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SWAP(key, i, j);
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}
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key->x = key->y = 0;
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}
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void
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RC4(RC4_KEY *key, const int len, const unsigned char *in, unsigned char *out)
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{
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int i, t;
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unsigned x, y;
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x = key->x;
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y = key->y;
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for (i = 0; i < len; i++) {
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x = (x + 1) % 256;
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y = (y + key->state[x]) % 256;
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SWAP(key, x, y);
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t = (key->state[x] + key->state[y]) % 256;
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*out++ = key->state[t] ^ *in++;
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}
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key->x = x;
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key->y = y;
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}
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