1 /* $OpenBSD: rc4.c,v 1.12 2024/08/11 13:02:39 jsing Exp $ */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
8 *
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 *
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 *
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
57 */
58
59 #include <endian.h>
60
61 #include <openssl/rc4.h>
62
63 #include "crypto_arch.h"
64
65 /* RC4 as implemented from a posting from
66 * Newsgroups: sci.crypt
67 * From: sterndark@netcom.com (David Sterndark)
68 * Subject: RC4 Algorithm revealed.
69 * Message-ID: <sternCvKL4B.Hyy@netcom.com>
70 * Date: Wed, 14 Sep 1994 06:35:31 GMT
71 */
72
73 #ifdef HAVE_RC4_INTERNAL
74 void rc4_internal(RC4_KEY *key, size_t len, const unsigned char *indata,
75 unsigned char *outdata);
76
77 #else
78 static void
rc4_internal(RC4_KEY * key,size_t len,const unsigned char * indata,unsigned char * outdata)79 rc4_internal(RC4_KEY *key, size_t len, const unsigned char *indata,
80 unsigned char *outdata)
81 {
82 RC4_INT *d;
83 RC4_INT x, y,tx, ty;
84 size_t i;
85
86 x = key->x;
87 y = key->y;
88 d = key->data;
89
90 #if defined(RC4_CHUNK)
91 /*
92 * The original reason for implementing this(*) was the fact that
93 * pre-21164a Alpha CPUs don't have byte load/store instructions
94 * and e.g. a byte store has to be done with 64-bit load, shift,
95 * and, or and finally 64-bit store. Peaking data and operating
96 * at natural word size made it possible to reduce amount of
97 * instructions as well as to perform early read-ahead without
98 * suffering from RAW (read-after-write) hazard. This resulted
99 * in ~40%(**) performance improvement on 21064 box with gcc.
100 * But it's not only Alpha users who win here:-) Thanks to the
101 * early-n-wide read-ahead this implementation also exhibits
102 * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending
103 * on sizeof(RC4_INT)).
104 *
105 * (*) "this" means code which recognizes the case when input
106 * and output pointers appear to be aligned at natural CPU
107 * word boundary
108 * (**) i.e. according to 'apps/openssl speed rc4' benchmark,
109 * crypto/rc4/rc4speed.c exhibits almost 70% speed-up...
110 *
111 * Caveats.
112 *
113 * - RC4_CHUNK="unsigned long long" should be a #1 choice for
114 * UltraSPARC. Unfortunately gcc generates very slow code
115 * (2.5-3 times slower than one generated by Sun's WorkShop
116 * C) and therefore gcc (at least 2.95 and earlier) should
117 * always be told that RC4_CHUNK="unsigned long".
118 *
119 * <appro@fy.chalmers.se>
120 */
121
122 # define RC4_STEP ( \
123 x=(x+1) &0xff, \
124 tx=d[x], \
125 y=(tx+y)&0xff, \
126 ty=d[y], \
127 d[y]=tx, \
128 d[x]=ty, \
129 (RC4_CHUNK)d[(tx+ty)&0xff]\
130 )
131
132 if ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) |
133 ((size_t)outdata & (sizeof(RC4_CHUNK) - 1))) == 0 ) {
134 RC4_CHUNK ichunk, otp;
135
136 /*
137 * I reckon we can afford to implement both endian
138 * cases and to decide which way to take at run-time
139 * because the machine code appears to be very compact
140 * and redundant 1-2KB is perfectly tolerable (i.e.
141 * in case the compiler fails to eliminate it:-). By
142 * suggestion from Terrel Larson <terr@terralogic.net>.
143 *
144 * Special notes.
145 *
146 * - compilers (those I've tried) don't seem to have
147 * problems eliminating either the operators guarded
148 * by "if (sizeof(RC4_CHUNK)==8)" or the condition
149 * expressions themselves so I've got 'em to replace
150 * corresponding #ifdefs from the previous version;
151 * - I chose to let the redundant switch cases when
152 * sizeof(RC4_CHUNK)!=8 be (were also #ifdefed
153 * before);
154 * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in
155 * [LB]ESHFT guards against "shift is out of range"
156 * warnings when sizeof(RC4_CHUNK)!=8
157 *
158 * <appro@fy.chalmers.se>
159 */
160 #if BYTE_ORDER == BIG_ENDIAN
161 # define BESHFT(c) (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
162 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
163 ichunk = *(RC4_CHUNK *)indata;
164 otp = RC4_STEP << BESHFT(0);
165 otp |= RC4_STEP << BESHFT(1);
166 otp |= RC4_STEP << BESHFT(2);
167 otp |= RC4_STEP << BESHFT(3);
168 if (sizeof(RC4_CHUNK) == 8) {
169 otp |= RC4_STEP << BESHFT(4);
170 otp |= RC4_STEP << BESHFT(5);
171 otp |= RC4_STEP << BESHFT(6);
172 otp |= RC4_STEP << BESHFT(7);
173 }
174 *(RC4_CHUNK *)outdata = otp^ichunk;
175 indata += sizeof(RC4_CHUNK);
176 outdata += sizeof(RC4_CHUNK);
177 }
178 #else
179 # define LESHFT(c) (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
180 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
181 ichunk = *(RC4_CHUNK *)indata;
182 otp = RC4_STEP;
183 otp |= RC4_STEP << 8;
184 otp |= RC4_STEP << 16;
185 otp |= RC4_STEP << 24;
186 if (sizeof(RC4_CHUNK) == 8) {
187 otp |= RC4_STEP << LESHFT(4);
188 otp |= RC4_STEP << LESHFT(5);
189 otp |= RC4_STEP << LESHFT(6);
190 otp |= RC4_STEP << LESHFT(7);
191 }
192 *(RC4_CHUNK *)outdata = otp ^ ichunk;
193 indata += sizeof(RC4_CHUNK);
194 outdata += sizeof(RC4_CHUNK);
195 }
196 #endif
197 }
198 #endif
199 #define LOOP(in,out) \
200 x=((x+1)&0xff); \
201 tx=d[x]; \
202 y=(tx+y)&0xff; \
203 d[x]=ty=d[y]; \
204 d[y]=tx; \
205 (out) = d[(tx+ty)&0xff]^ (in);
206
207 #ifndef RC4_INDEX
208 #define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++))
209 #else
210 #define RC4_LOOP(a,b,i) LOOP(a[i],b[i])
211 #endif
212
213 i = len >> 3;
214 if (i) {
215 for (;;) {
216 RC4_LOOP(indata, outdata, 0);
217 RC4_LOOP(indata, outdata, 1);
218 RC4_LOOP(indata, outdata, 2);
219 RC4_LOOP(indata, outdata, 3);
220 RC4_LOOP(indata, outdata, 4);
221 RC4_LOOP(indata, outdata, 5);
222 RC4_LOOP(indata, outdata, 6);
223 RC4_LOOP(indata, outdata, 7);
224 #ifdef RC4_INDEX
225 indata += 8;
226 outdata += 8;
227 #endif
228 if (--i == 0)
229 break;
230 }
231 }
232 i = len&0x07;
233 if (i) {
234 for (;;) {
235 RC4_LOOP(indata, outdata, 0);
236 if (--i == 0)
237 break;
238 RC4_LOOP(indata, outdata, 1);
239 if (--i == 0)
240 break;
241 RC4_LOOP(indata, outdata, 2);
242 if (--i == 0)
243 break;
244 RC4_LOOP(indata, outdata, 3);
245 if (--i == 0)
246 break;
247 RC4_LOOP(indata, outdata, 4);
248 if (--i == 0)
249 break;
250 RC4_LOOP(indata, outdata, 5);
251 if (--i == 0)
252 break;
253 RC4_LOOP(indata, outdata, 6);
254 if (--i == 0)
255 break;
256 }
257 }
258 key->x = x;
259 key->y = y;
260 }
261 #endif
262
263 #ifdef HAVE_RC4_SET_KEY_INTERNAL
264 void rc4_set_key_internal(RC4_KEY *key, int len, const unsigned char *data);
265
266 #else
267 static inline void
rc4_set_key_internal(RC4_KEY * key,int len,const unsigned char * data)268 rc4_set_key_internal(RC4_KEY *key, int len, const unsigned char *data)
269 {
270 RC4_INT tmp;
271 int id1, id2;
272 RC4_INT *d;
273 unsigned int i;
274
275 d = &(key->data[0]);
276 key->x = 0;
277 key->y = 0;
278 id1 = id2 = 0;
279
280 #define SK_LOOP(d,n) { \
281 tmp=d[(n)]; \
282 id2 = (data[id1] + tmp + id2) & 0xff; \
283 if (++id1 == len) id1=0; \
284 d[(n)]=d[id2]; \
285 d[id2]=tmp; }
286
287 for (i = 0; i < 256; i++)
288 d[i] = i;
289 for (i = 0; i < 256; i += 4) {
290 SK_LOOP(d, i + 0);
291 SK_LOOP(d, i + 1);
292 SK_LOOP(d, i + 2);
293 SK_LOOP(d, i + 3);
294 }
295 }
296 #endif
297
298 void
RC4(RC4_KEY * key,size_t len,const unsigned char * indata,unsigned char * outdata)299 RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
300 unsigned char *outdata)
301 {
302 rc4_internal(key, len, indata, outdata);
303 }
304 LCRYPTO_ALIAS(RC4);
305
306 void
RC4_set_key(RC4_KEY * key,int len,const unsigned char * data)307 RC4_set_key(RC4_KEY *key, int len, const unsigned char *data)
308 {
309 rc4_set_key_internal(key, len, data);
310 }
311 LCRYPTO_ALIAS(RC4_set_key);
312