/*

 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <openssl/rc4.h>

#include "rc4_local.h"

/*-

 * RC4 as implemented from a posting from

 * Newsgroups: sci.crypt

 * Subject: RC4 Algorithm revealed.

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

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

 */

void RC4(RC4_KEY *key, size_t len, const unsigned char *indata,

         unsigned char *outdata)

{

    register RC4_INT *d;

    register RC4_INT x, y, tx, ty;

    size_t 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]=ty=d[y]; \

                d[y]=tx; \

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

    i = len >> 3;

    if (i) {

        for (;;) {

            LOOP(indata[0], outdata[0]);

            LOOP(indata[1], outdata[1]);

            LOOP(indata[2], outdata[2]);

            LOOP(indata[3], outdata[3]);

            LOOP(indata[4], outdata[4]);

            LOOP(indata[5], outdata[5]);

            LOOP(indata[6], outdata[6]);

            LOOP(indata[7], outdata[7]);

            indata += 8;

            outdata += 8;

            if (--i == 0)

                break;

        }

    }

    i = len & 0x07;

    if (i) {

        for (;;) {

            LOOP(indata[0], outdata[0]);

            if (--i == 0)

                break;

            LOOP(indata[1], outdata[1]);

            if (--i == 0)

                break;

            LOOP(indata[2], outdata[2]);

            if (--i == 0)

                break;

            LOOP(indata[3], outdata[3]);

            if (--i == 0)

                break;

            LOOP(indata[4], outdata[4]);

            if (--i == 0)

                break;

            LOOP(indata[5], outdata[5]);

            if (--i == 0)

                break;

            LOOP(indata[6], outdata[6]);

            if (--i == 0)

                break;

        }

    }

    key->x = x;

    key->y = y;

}