crypto/rc4/rc4_enc.c

   1 /*
   2  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/rc4.h>
  11 #include "rc4_locl.h"
  12
  13 /*-
  14  * RC4 as implemented from a posting from
  15  * Newsgroups: sci.crypt
  16  * Subject: RC4 Algorithm revealed.
  17  * Message-ID: <sternCvKL4B.Hyy@netcom.com>
  18  * Date: Wed, 14 Sep 1994 06:35:31 GMT
  19  */
  20
  21 void RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
  22          unsigned char *outdata)
  23 {
  24     register RC4_INT *d;
  25     register RC4_INT x, y, tx, ty;
  26     size_t i;
  27
  28     x = key->x;
  29     y = key->y;
  30     d = key->data;
  31
  32 #define LOOP(in,out) \
  33                 x=((x+1)&0xff); \
  34                 tx=d[x]; \
  35                 y=(tx+y)&0xff; \
  36                 d[x]=ty=d[y]; \
  37                 d[y]=tx; \
  38                 (out) = d[(tx+ty)&0xff]^ (in);
  39
  40     i = len >> 3;
  41     if (i) {
  42         for (;;) {
  43             LOOP(indata[0], outdata[0]);
  44             LOOP(indata[1], outdata[1]);
  45             LOOP(indata[2], outdata[2]);
  46             LOOP(indata[3], outdata[3]);
  47             LOOP(indata[4], outdata[4]);
  48             LOOP(indata[5], outdata[5]);
  49             LOOP(indata[6], outdata[6]);
  50             LOOP(indata[7], outdata[7]);
  51             indata += 8;
  52             outdata += 8;
  53             if (--i == 0)
  54                 break;
  55         }
  56     }
  57     i = len & 0x07;
  58     if (i) {
  59         for (;;) {
  60             LOOP(indata[0], outdata[0]);
  61             if (--i == 0)
  62                 break;
  63             LOOP(indata[1], outdata[1]);
  64             if (--i == 0)
  65                 break;
  66             LOOP(indata[2], outdata[2]);
  67             if (--i == 0)
  68                 break;
  69             LOOP(indata[3], outdata[3]);
  70             if (--i == 0)
  71                 break;
  72             LOOP(indata[4], outdata[4]);
  73             if (--i == 0)
  74                 break;
  75             LOOP(indata[5], outdata[5]);
  76             if (--i == 0)
  77                 break;
  78             LOOP(indata[6], outdata[6]);
  79             if (--i == 0)
  80                 break;
  81         }
  82     }
  83     key->x = x;
  84     key->y = y;
  85 }