1 /*
2 * Copyright 1995-2020 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 /*
11 * RC4 low level APIs are deprecated for public use, but still ok for internal
12 * use.
13 */
14 #include "internal/deprecated.h"
15
16 #include <openssl/rc4.h>
17 #include "rc4_local.h"
18
19 /*-
20 * RC4 as implemented from a posting from
21 * Newsgroups: sci.crypt
22 * Subject: RC4 Algorithm revealed.
23 * Message-ID: <sternCvKL4B.Hyy@netcom.com>
24 * Date: Wed, 14 Sep 1994 06:35:31 GMT
25 */
26
RC4(RC4_KEY * key,size_t len,const unsigned char * indata,unsigned char * outdata)27 void RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
28 unsigned char *outdata)
29 {
30 register RC4_INT *d;
31 register RC4_INT x, y, tx, ty;
32 size_t i;
33
34 x = key->x;
35 y = key->y;
36 d = key->data;
37
38 #define LOOP(in,out) \
39 x=((x+1)&0xff); \
40 tx=d[x]; \
41 y=(tx+y)&0xff; \
42 d[x]=ty=d[y]; \
43 d[y]=tx; \
44 (out) = d[(tx+ty)&0xff]^ (in);
45
46 i = len >> 3;
47 if (i) {
48 for (;;) {
49 LOOP(indata[0], outdata[0]);
50 LOOP(indata[1], outdata[1]);
51 LOOP(indata[2], outdata[2]);
52 LOOP(indata[3], outdata[3]);
53 LOOP(indata[4], outdata[4]);
54 LOOP(indata[5], outdata[5]);
55 LOOP(indata[6], outdata[6]);
56 LOOP(indata[7], outdata[7]);
57 indata += 8;
58 outdata += 8;
59 if (--i == 0)
60 break;
61 }
62 }
63 i = len & 0x07;
64 if (i) {
65 for (;;) {
66 LOOP(indata[0], outdata[0]);
67 if (--i == 0)
68 break;
69 LOOP(indata[1], outdata[1]);
70 if (--i == 0)
71 break;
72 LOOP(indata[2], outdata[2]);
73 if (--i == 0)
74 break;
75 LOOP(indata[3], outdata[3]);
76 if (--i == 0)
77 break;
78 LOOP(indata[4], outdata[4]);
79 if (--i == 0)
80 break;
81 LOOP(indata[5], outdata[5]);
82 if (--i == 0)
83 break;
84 LOOP(indata[6], outdata[6]);
85 if (--i == 0)
86 break;
87 }
88 }
89 key->x = x;
90 key->y = y;
91 }
92
