A local copy of OpenSSL from GitHub
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/*
* 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_locl.h"
/*-
* 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(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;
}