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/* lib/rc4/rc4_enc.c */

/* Copyright (C) 1995-1997 Eric Young (eay@mincom.oz.au)

 * All rights reserved.

 *

 * This file is part of an SSL implementation written

 * by Eric Young (eay@mincom.oz.au).

 * The implementation was written so as to conform with Netscapes SSL

 * specification.  This library and applications are

 * FREE FOR COMMERCIAL AND NON-COMMERCIAL USE

 * as long as the following conditions are aheared to.

 *

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.  If this code is used in a product,

 * Eric Young should be given attribution as the author of the parts used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. 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.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *    This product includes software developed by Eric Young (eay@mincom.oz.au)

 *

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 AUTHOR 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 licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.]

 */

/* WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING

 *

 * Always modify rc2_enc.org since rc2_enc.c is automatically generated from

 * it during SSLeay configuration.

 * WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING

 */

#include "rc4.h"

/* if this is defined data[i] is used instead of *data, this is a %20

 * speedup on x86 */

#undef RC4_INDEX

char *RC4_version="RC4 part of SSLeay 0.6.6a 24-Jun-1998";

char *RC4_options()

        {

#ifdef RC4_INDEX

        if (sizeof(RC4_INT) == 1)

                return("rc4(idx,char)");

        else

                return("rc4(idx,int)");

#else

        if (sizeof(RC4_INT) == 1)

                return("rc4(ptr,char)");

        else

                return("rc4(ptr,int)");

#endif

        }

/* RC4 as implemented from a posting from

 * Newsgroups: sci.crypt

 * From: sterndark@netcom.com (David Sterndark)

 * Subject: RC4 Algorithm revealed.

 * Message-ID: <sternCvKL4B.Hyy@netcom.com>

 * Date: Wed, 14 Sep 1994 06:35:31 GMT

 */

void RC4_set_key(key, len, data)

RC4_KEY *key;

int len;

register unsigned char *data;

        {

        register RC4_INT tmp;

        register int id1,id2;

        register RC4_INT *d;

        unsigned int i;

        d= &(key->data[0]);

        for (i=0; i<256; i++)

                d[i]=i;

        key->x = 0;

        key->y = 0;

        id1=id2=0;

#define SK_LOOP(n) { \

                tmp=d[(n)]; \

                id2 = (data[id1] + tmp + id2) & 0xff; \

                if (++id1 == len) id1=0; \

                d[(n)]=d[id2]; \

                d[id2]=tmp; }

        for (i=0; i < 256; i+=4)

                {

                SK_LOOP(i+0);

                SK_LOOP(i+1);

                SK_LOOP(i+2);

                SK_LOOP(i+3);

                }

        }

void RC4(key, len, indata, outdata)

RC4_KEY *key;

unsigned long len;

unsigned char *indata;

unsigned char *outdata;

        {

        register RC4_INT *d;

        register RC4_INT x,y,tx;

        int i;

        x=key->x;

        y=key->y;

        d=key->data;

#define LOOP(in,out) \

                x=((x+1)&0xff); \

                tx=d[x]; \

                y=(tx+y)&0xff; \

                d[x]=d[y]; \

                d[y]=tx; \

                (out) = d[(tx+d[x])&0xff]^ (in);

#ifndef RC4_INDEX

#define RC4_LOOP(a,b)   LOOP(*((a)++),*((b)++))

#else

#define RC4_LOOP(a,b)   LOOP(a[i],b[i])

        indata+=len;

        outdata+=len;

#endif

        i= -(int)len;

        for (;;)

                {

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                RC4_LOOP(indata,outdata); if (++i == 0) break;

                }

        key->x=x;

        key->y=y;

        }