1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.]
58 #include <openssl/rc4.h>
62 * RC4 as implemented from a posting from
63 * Newsgroups: sci.crypt
64 * From: sterndark@netcom.com (David Sterndark)
65 * Subject: RC4 Algorithm revealed.
66 * Message-ID: <sternCvKL4B.Hyy@netcom.com>
67 * Date: Wed, 14 Sep 1994 06:35:31 GMT
70 void RC4(RC4_KEY *key, size_t len, const unsigned char *indata,
71 unsigned char *outdata)
74 register RC4_INT x, y, tx, ty;
81 #if defined(RC4_CHUNK) && !defined(PEDANTIC)
83 * The original reason for implementing this(*) was the fact that
84 * pre-21164a Alpha CPUs don't have byte load/store instructions
85 * and e.g. a byte store has to be done with 64-bit load, shift,
86 * and, or and finally 64-bit store. Peaking data and operating
87 * at natural word size made it possible to reduce amount of
88 * instructions as well as to perform early read-ahead without
89 * suffering from RAW (read-after-write) hazard. This resulted
90 * in ~40%(**) performance improvement on 21064 box with gcc.
91 * But it's not only Alpha users who win here:-) Thanks to the
92 * early-n-wide read-ahead this implementation also exhibits
93 * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending
94 * on sizeof(RC4_INT)).
96 * (*) "this" means code which recognizes the case when input
97 * and output pointers appear to be aligned at natural CPU
99 * (**) i.e. according to 'apps/openssl speed rc4' benchmark,
100 * crypto/rc4/rc4speed.c exhibits almost 70% speed-up...
104 * - RC4_CHUNK="unsigned long long" should be a #1 choice for
105 * UltraSPARC. Unfortunately gcc generates very slow code
106 * (2.5-3 times slower than one generated by Sun's WorkShop
107 * C) and therefore gcc (at least 2.95 and earlier) should
108 * always be told that RC4_CHUNK="unsigned long".
110 * <appro@fy.chalmers.se>
113 # define RC4_STEP ( \
120 (RC4_CHUNK)d[(tx+ty)&0xff]\
123 if ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) |
124 ((size_t)outdata & (sizeof(RC4_CHUNK) - 1))) == 0) {
125 RC4_CHUNK ichunk, otp;
134 * I reckon we can afford to implement both endian
135 * cases and to decide which way to take at run-time
136 * because the machine code appears to be very compact
137 * and redundant 1-2KB is perfectly tolerable (i.e.
138 * in case the compiler fails to eliminate it:-). By
139 * suggestion from Terrel Larson <terr@terralogic.net>
140 * who also stands for the is_endian union:-)
144 * - is_endian is declared automatic as doing otherwise
145 * (declaring static) prevents gcc from eliminating
146 * the redundant code;
147 * - compilers (those I've tried) don't seem to have
148 * problems eliminating either the operators guarded
149 * by "if (sizeof(RC4_CHUNK)==8)" or the condition
150 * expressions themselves so I've got 'em to replace
151 * corresponding #ifdefs from the previous version;
152 * - I chose to let the redundant switch cases when
153 * sizeof(RC4_CHUNK)!=8 be (were also #ifdefed
155 * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in
156 * [LB]ESHFT guards against "shift is out of range"
157 * warnings when sizeof(RC4_CHUNK)!=8
159 * <appro@fy.chalmers.se>
161 if (!is_endian.little) { /* BIG-ENDIAN CASE */
162 # define BESHFT(c) (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
163 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
164 ichunk = *(RC4_CHUNK *) indata;
165 otp = RC4_STEP << BESHFT(0);
166 otp |= RC4_STEP << BESHFT(1);
167 otp |= RC4_STEP << BESHFT(2);
168 otp |= RC4_STEP << BESHFT(3);
169 if (sizeof(RC4_CHUNK) == 8) {
170 otp |= RC4_STEP << BESHFT(4);
171 otp |= RC4_STEP << BESHFT(5);
172 otp |= RC4_STEP << BESHFT(6);
173 otp |= RC4_STEP << BESHFT(7);
175 *(RC4_CHUNK *) outdata = otp ^ ichunk;
176 indata += sizeof(RC4_CHUNK);
177 outdata += sizeof(RC4_CHUNK);
180 RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;
182 ichunk = *(RC4_CHUNK *) indata;
183 ochunk = *(RC4_CHUNK *) outdata;
186 mask <<= (sizeof(RC4_CHUNK) - len) << 3;
187 switch (len & (sizeof(RC4_CHUNK) - 1)) {
189 otp = RC4_STEP << i, i -= 8;
191 otp |= RC4_STEP << i, i -= 8;
193 otp |= RC4_STEP << i, i -= 8;
195 otp |= RC4_STEP << i, i -= 8;
197 otp |= RC4_STEP << i, i -= 8;
199 otp |= RC4_STEP << i, i -= 8;
201 otp |= RC4_STEP << i, i -= 8;
203 * it's never the case,
204 * but it has to be here
209 ochunk |= (otp ^ ichunk) & mask;
210 *(RC4_CHUNK *) outdata = ochunk;
215 } else { /* LITTLE-ENDIAN CASE */
216 # define LESHFT(c) (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
217 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
218 ichunk = *(RC4_CHUNK *) indata;
220 otp |= RC4_STEP << 8;
221 otp |= RC4_STEP << 16;
222 otp |= RC4_STEP << 24;
223 if (sizeof(RC4_CHUNK) == 8) {
224 otp |= RC4_STEP << LESHFT(4);
225 otp |= RC4_STEP << LESHFT(5);
226 otp |= RC4_STEP << LESHFT(6);
227 otp |= RC4_STEP << LESHFT(7);
229 *(RC4_CHUNK *) outdata = otp ^ ichunk;
230 indata += sizeof(RC4_CHUNK);
231 outdata += sizeof(RC4_CHUNK);
234 RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;
236 ichunk = *(RC4_CHUNK *) indata;
237 ochunk = *(RC4_CHUNK *) outdata;
240 mask >>= (sizeof(RC4_CHUNK) - len) << 3;
241 switch (len & (sizeof(RC4_CHUNK) - 1)) {
243 otp = RC4_STEP, i += 8;
245 otp |= RC4_STEP << i, i += 8;
247 otp |= RC4_STEP << i, i += 8;
249 otp |= RC4_STEP << i, i += 8;
251 otp |= RC4_STEP << i, i += 8;
253 otp |= RC4_STEP << i, i += 8;
255 otp |= RC4_STEP << i, i += 8;
257 * it's never the case,
258 * but it has to be here
263 ochunk |= (otp ^ ichunk) & mask;
264 *(RC4_CHUNK *) outdata = ochunk;
272 #define LOOP(in,out) \
278 (out) = d[(tx+ty)&0xff]^ (in);
281 # define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++))
283 # define RC4_LOOP(a,b,i) LOOP(a[i],b[i])
289 RC4_LOOP(indata, outdata, 0);
290 RC4_LOOP(indata, outdata, 1);
291 RC4_LOOP(indata, outdata, 2);
292 RC4_LOOP(indata, outdata, 3);
293 RC4_LOOP(indata, outdata, 4);
294 RC4_LOOP(indata, outdata, 5);
295 RC4_LOOP(indata, outdata, 6);
296 RC4_LOOP(indata, outdata, 7);
308 RC4_LOOP(indata, outdata, 0);
311 RC4_LOOP(indata, outdata, 1);
314 RC4_LOOP(indata, outdata, 2);
317 RC4_LOOP(indata, outdata, 3);
320 RC4_LOOP(indata, outdata, 4);
323 RC4_LOOP(indata, outdata, 5);
326 RC4_LOOP(indata, outdata, 6);