aboutsummaryrefslogtreecommitdiff
path: root/openssl/crypto/rc4/rc4_enc.c
blob: 0f0a2487a7f7292c4e15f98d3c75cbccdb1c1fc2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
/* crypto/rc4/rc4_enc.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#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;

#if defined(RC4_CHUNK) && !defined(PEDANTIC)
    /*-
     * The original reason for implementing this(*) was the fact that
     * pre-21164a Alpha CPUs don't have byte load/store instructions
     * and e.g. a byte store has to be done with 64-bit load, shift,
     * and, or and finally 64-bit store. Peaking data and operating
     * at natural word size made it possible to reduce amount of
     * instructions as well as to perform early read-ahead without
     * suffering from RAW (read-after-write) hazard. This resulted
     * in ~40%(**) performance improvement on 21064 box with gcc.
     * But it's not only Alpha users who win here:-) Thanks to the
     * early-n-wide read-ahead this implementation also exhibits
     * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending
     * on sizeof(RC4_INT)).
     *
     * (*)  "this" means code which recognizes the case when input
     *      and output pointers appear to be aligned at natural CPU
     *      word boundary
     * (**) i.e. according to 'apps/openssl speed rc4' benchmark,
     *      crypto/rc4/rc4speed.c exhibits almost 70% speed-up...
     *
     * Cavets.
     *
     * - RC4_CHUNK="unsigned long long" should be a #1 choice for
     *   UltraSPARC. Unfortunately gcc generates very slow code
     *   (2.5-3 times slower than one generated by Sun's WorkShop
     *   C) and therefore gcc (at least 2.95 and earlier) should
     *   always be told that RC4_CHUNK="unsigned long".
     *
     *                                      <appro@fy.chalmers.se>
     */

# define RC4_STEP       ( \
                        x=(x+1) &0xff,  \
                        tx=d[x],        \
                        y=(tx+y)&0xff,  \
                        ty=d[y],        \
                        d[y]=tx,        \
                        d[x]=ty,        \
                        (RC4_CHUNK)d[(tx+ty)&0xff]\
                        )

    if ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) |
         ((size_t)outdata & (sizeof(RC4_CHUNK) - 1))) == 0) {
        RC4_CHUNK ichunk, otp;
        const union {
            long one;
            char little;
        } is_endian = {
            1
        };

        /*-
         * I reckon we can afford to implement both endian
         * cases and to decide which way to take at run-time
         * because the machine code appears to be very compact
         * and redundant 1-2KB is perfectly tolerable (i.e.
         * in case the compiler fails to eliminate it:-). By
         * suggestion from Terrel Larson <terr@terralogic.net>
         * who also stands for the is_endian union:-)
         *
         * Special notes.
         *
         * - is_endian is declared automatic as doing otherwise
         *   (declaring static) prevents gcc from eliminating
         *   the redundant code;
         * - compilers (those I've tried) don't seem to have
         *   problems eliminating either the operators guarded
         *   by "if (sizeof(RC4_CHUNK)==8)" or the condition
         *   expressions themselves so I've got 'em to replace
         *   corresponding #ifdefs from the previous version;
         * - I chose to let the redundant switch cases when
         *   sizeof(RC4_CHUNK)!=8 be (were also #ifdefed
         *   before);
         * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in
         *   [LB]ESHFT guards against "shift is out of range"
         *   warnings when sizeof(RC4_CHUNK)!=8
         *
         *                      <appro@fy.chalmers.se>
         */
        if (!is_endian.little) { /* BIG-ENDIAN CASE */
# define BESHFT(c)      (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
            for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
                ichunk = *(RC4_CHUNK *) indata;
                otp = RC4_STEP << BESHFT(0);
                otp |= RC4_STEP << BESHFT(1);
                otp |= RC4_STEP << BESHFT(2);
                otp |= RC4_STEP << BESHFT(3);
                if (sizeof(RC4_CHUNK) == 8) {
                    otp |= RC4_STEP << BESHFT(4);
                    otp |= RC4_STEP << BESHFT(5);
                    otp |= RC4_STEP << BESHFT(6);
                    otp |= RC4_STEP << BESHFT(7);
                }
                *(RC4_CHUNK *) outdata = otp ^ ichunk;
                indata += sizeof(RC4_CHUNK);
                outdata += sizeof(RC4_CHUNK);
            }
            if (len) {
                RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;

                ichunk = *(RC4_CHUNK *) indata;
                ochunk = *(RC4_CHUNK *) outdata;
                otp = 0;
                i = BESHFT(0);
                mask <<= (sizeof(RC4_CHUNK) - len) << 3;
                switch (len & (sizeof(RC4_CHUNK) - 1)) {
                case 7:
                    otp = RC4_STEP << i, i -= 8;
                case 6:
                    otp |= RC4_STEP << i, i -= 8;
                case 5:
                    otp |= RC4_STEP << i, i -= 8;
                case 4:
                    otp |= RC4_STEP << i, i -= 8;
                case 3:
                    otp |= RC4_STEP << i, i -= 8;
                case 2:
                    otp |= RC4_STEP << i, i -= 8;
                case 1:
                    otp |= RC4_STEP << i, i -= 8;
                case 0:;       /*
                                 * it's never the case,
                                 * but it has to be here
                                 * for ultrix?
                                 */
                }
                ochunk &= ~mask;
                ochunk |= (otp ^ ichunk) & mask;
                *(RC4_CHUNK *) outdata = ochunk;
            }
            key->x = x;
            key->y = y;
            return;
        } else {                /* LITTLE-ENDIAN CASE */
# define LESHFT(c)      (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
            for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) {
                ichunk = *(RC4_CHUNK *) indata;
                otp = RC4_STEP;
                otp |= RC4_STEP << 8;
                otp |= RC4_STEP << 16;
                otp |= RC4_STEP << 24;
                if (sizeof(RC4_CHUNK) == 8) {
                    otp |= RC4_STEP << LESHFT(4);
                    otp |= RC4_STEP << LESHFT(5);
                    otp |= RC4_STEP << LESHFT(6);
                    otp |= RC4_STEP << LESHFT(7);
                }
                *(RC4_CHUNK *) outdata = otp ^ ichunk;
                indata += sizeof(RC4_CHUNK);
                outdata += sizeof(RC4_CHUNK);
            }
            if (len) {
                RC4_CHUNK mask = (RC4_CHUNK) - 1, ochunk;

                ichunk = *(RC4_CHUNK *) indata;
                ochunk = *(RC4_CHUNK *) outdata;
                otp = 0;
                i = 0;
                mask >>= (sizeof(RC4_CHUNK) - len) << 3;
                switch (len & (sizeof(RC4_CHUNK) - 1)) {
                case 7:
                    otp = RC4_STEP, i += 8;
                case 6:
                    otp |= RC4_STEP << i, i += 8;
                case 5:
                    otp |= RC4_STEP << i, i += 8;
                case 4:
                    otp |= RC4_STEP << i, i += 8;
                case 3:
                    otp |= RC4_STEP << i, i += 8;
                case 2:
                    otp |= RC4_STEP << i, i += 8;
                case 1:
                    otp |= RC4_STEP << i, i += 8;
                case 0:;       /*
                                 * it's never the case,
                                 * but it has to be here
                                 * for ultrix?
                                 */
                }
                ochunk &= ~mask;
                ochunk |= (otp ^ ichunk) & mask;
                *(RC4_CHUNK *) outdata = ochunk;
            }
            key->x = x;
            key->y = y;
            return;
        }
    }
#endif
#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);

#ifndef RC4_INDEX
# define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++))
#else
# define RC4_LOOP(a,b,i) LOOP(a[i],b[i])
#endif

    i = len >> 3;
    if (i) {
        for (;;) {
            RC4_LOOP(indata, outdata, 0);
            RC4_LOOP(indata, outdata, 1);
            RC4_LOOP(indata, outdata, 2);
            RC4_LOOP(indata, outdata, 3);
            RC4_LOOP(indata, outdata, 4);
            RC4_LOOP(indata, outdata, 5);
            RC4_LOOP(indata, outdata, 6);
            RC4_LOOP(indata, outdata, 7);
#ifdef RC4_INDEX
            indata += 8;
            outdata += 8;
#endif
            if (--i == 0)
                break;
        }
    }
    i = len & 0x07;
    if (i) {
        for (;;) {
            RC4_LOOP(indata, outdata, 0);
            if (--i == 0)
                break;
            RC4_LOOP(indata, outdata, 1);
            if (--i == 0)
                break;
            RC4_LOOP(indata, outdata, 2);
            if (--i == 0)
                break;
            RC4_LOOP(indata, outdata, 3);
            if (--i == 0)
                break;
            RC4_LOOP(indata, outdata, 4);
            if (--i == 0)
                break;
            RC4_LOOP(indata, outdata, 5);
            if (--i == 0)
                break;
            RC4_LOOP(indata, outdata, 6);
            if (--i == 0)
                break;
        }
    }
    key->x = x;
    key->y = y;
}