File: serpent-encrypt.c

package info (click to toggle)
nettle 3.5.1+really3.4.1-1
  • links: PTS, VCS
  • area: main
  • in suites: sid
  • size: 8,012 kB
  • sloc: ansic: 51,527; asm: 12,157; sh: 3,632; makefile: 846; cpp: 71; awk: 7
file content (536 lines) | stat: -rw-r--r-- 14,839 bytes parent folder | download | duplicates (4)
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
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
/* serpent-encrypt.c

   The serpent block cipher.

   For more details on this algorithm, see the Serpent website at
   http://www.cl.cam.ac.uk/~rja14/serpent.html

   Copyright (C) 2011  Niels Möller
   Copyright (C) 2010, 2011  Simon Josefsson
   Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.

   This file is part of GNU Nettle.

   GNU Nettle is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.

   GNU Nettle is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see http://www.gnu.org/licenses/.
*/

/* This file is derived from cipher/serpent.c in Libgcrypt v1.4.6.
   The adaption to Nettle was made by Simon Josefsson on 2010-12-07
   with final touches on 2011-05-30.  Changes include replacing
   libgcrypt with nettle in the license template, renaming
   serpent_context to serpent_ctx, renaming u32 to uint32_t, removing
   libgcrypt stubs and selftests, modifying entry function prototypes,
   using FOR_BLOCKS to iterate through data in encrypt/decrypt, using
   LE_READ_UINT32 and LE_WRITE_UINT32 to access data in
   encrypt/decrypt, and running indent on the code. */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <assert.h>
#include <limits.h>

#include "serpent.h"

#include "macros.h"
#include "serpent-internal.h"

/* These are the S-Boxes of Serpent.  They are copied from Serpents
   reference implementation (the optimized one, contained in
   `floppy2') and are therefore:

     Copyright (C) 1998 Ross Anderson, Eli Biham, Lars Knudsen.

  To quote the Serpent homepage
  (http://www.cl.cam.ac.uk/~rja14/serpent.html):

  "Serpent is now completely in the public domain, and we impose no
   restrictions on its use.  This was announced on the 21st August at
   the First AES Candidate Conference. The optimised implementations
   in the submission package are now under the GNU PUBLIC LICENSE
   (GPL), although some comments in the code still say otherwise. You
   are welcome to use Serpent for any application."  */

/* S0:  3  8 15  1 10  6  5 11 14 13  4  2  7  0  9 12 */
/* Could easily let y0, y1 overlap with x0, x1, and possibly also x2 and y2 */
#define SBOX0(x0, x1, x2, x3, y0, y1, y2, y3)	\
  do {							\
    y3  = x1 ^ x2;					\
    y0  = x0 | x3;					\
    y1  = x0 ^ x1;					\
    y3 ^= y0;						\
    y2  = x2 | y3;					\
    x0 ^= x3;						\
    y2 &= x3;						\
    x3 ^= x2;						\
    x2 |= x1;						\
    y0  = y1 & x2;					\
    y2 ^= y0;						\
    y0 &= y2;						\
    y0 ^= x2;						\
    x1 &= x0;						\
    y0 ^= x0;						\
    y0  = ~ y0;						\
    y1  = y0 ^ x1;					\
    y1 ^= x3;						\
  } while (0)

/* FIXME: Arrange for some overlap between inputs and outputs? */
/* S1: 15 12  2  7  9  0  5 10  1 11 14  8  6 13  3  4 */
/* Original single-assignment form:
   
     t01 = x0  | x3;
     t02 = x2  ^ x3;
     t03 =     ~ x1;
     t04 = x0  ^ x2;
     t05 = x0  | t03;
     t06 = x3  & t04;
     t07 = t01 & t02;
     t08 = x1  | t06;
     y2  = t02 ^ t05;
     t10 = t07 ^ t08;
     t11 = t01 ^ t10;
     t12 = y2  ^ t11;
     t13 = x1  & x3;
     y3  =     ~ t10;
     y1  = t13 ^ t12;
     t16 = t10 | y1;
     t17 = t05 & t16;
     y0  = x2  ^ t17;
*/
#define SBOX1(x0, x1, x2, x3, y0, y1, y2, y3)		\
  do {							\
    y1  = x0 | x3;					\
    y2  = x2 ^ x3;					\
    y0  = ~ x1;						\
    y3  = x0 ^ x2;					\
    y0 |= x0;						\
    y3 &= x3;						\
    x0 = y1 & y2;					\
    y3 |= x1;						\
    y2 ^= y0;						\
    y3 ^= x0;						\
    x0  = y1 ^ y3;					\
    x0 ^= y2;						\
    y1  = x1 & x3;					\
    y1 ^= x0;						\
    x3  = y1 | y3;					\
    y3  = ~ y3;						\
    y0 &= x3;						\
    y0 ^= x2;						\
  } while (0)

/* FIXME: Arrange for some overlap between inputs and outputs? */
/* S2:  8  6  7  9  3 12 10 15 13  1 14  4  0 11  5  2 */
#define SBOX2(x0, x1, x2, x3, y0, y1, y2, y3)	\
  do {							\
    y2  = x0 | x2;					\
    y1  = x0 ^ x1;					\
    y3  = x3 ^ y2;					\
    y0  = y1 ^ y3;					\
    x3 |= x0;						\
    x2 ^= y0;						\
    x0  = x1 ^ x2;					\
    x2 |= x1;						\
    x0 &= y2;						\
    y3 ^= x2;						\
    y1 |= y3;						\
    y1 ^= x0;						\
    y2  = y3 ^ y1;					\
    y2 ^= x1;						\
    y3  = ~ y3;						\
    y2 ^= x3;						\
  } while (0)

/* S3:  0 15 11  8 12  9  6  3 13  1  2  4 10  7  5 14 */
/* Original single-assignment form:
   
     t01 = x0  ^ x2;
     t02 = x0  | x3;
     t03 = x0  & x3;
     t04 = t01 & t02;
     t05 = x1  | t03;
     t06 = x0  & x1;
     t07 = x3  ^ t04;
     t08 = x2  | t06;
     t09 = x1  ^ t07;
     t10 = x3  & t05;
     t11 = t02 ^ t10;
     y3  = t08 ^ t09;
     t13 = x3  | y3;
     t14 = x0  | t07;
     t15 = x1  & t13;
     y2  = t08 ^ t11;
     y0  = t14 ^ t15;
     y1  = t05 ^ t04;
*/
#define SBOX3(x0, x1, x2, x3, y0, y1, y2, y3)	\
  do {							\
    y1  = x0 ^ x2;					\
    y0  = x0 | x3;					\
    y3  = x0 & x3;					\
    y1 &= y0;						\
    y3 |= x1;						\
    y2  = x0 & x1;					\
    y2 |= x2;						\
    x2  = x3 ^ y1;					\
    y1 ^= y3;						\
    x0 |= x2;						\
    x2 ^= x1;						\
    y3 &= x3;						\
    y0 ^= y3;						\
    y3  = y2 ^ x2;					\
    y2 ^= y0;						\
    x3 |= y3;						\
    x1 &= x3;						\
    y0  = x0 ^ x1;					\
  } while (0)


/* S4:  1 15  8  3 12  0 11  6  2  5  4 10  9 14  7 13 */
/* Original single-assignment form:
    t01 = x0  | x1;
    t02 = x1  | x2;
    t03 = x0  ^ t02;
    t04 = x1  ^ x3;
    t05 = x3  | t03;
    t06 = x3  & t01;
    y3  = t03 ^ t06;
    t08 = y3  & t04;
    t09 = t04 & t05;
    t10 = x2  ^ t06;
    t11 = x1  & x2;
    t12 = t04 ^ t08;
    t13 = t11 | t03;
    t14 = t10 ^ t09;
    t15 = x0  & t05;
    t16 = t11 | t12;
    y2  = t13 ^ t08;
    y1  = t15 ^ t16;
    y0  =     ~ t14;
*/
#define SBOX4(x0, x1, x2, x3, y0, y1, y2, y3)	\
  do {							\
    y3  = x0 | x1;					\
    y2  = x1 | x2;					\
    y2 ^= x0;						\
    y3 &= x3;						\
    y0  = x1 ^ x3;					\
    x3 |= y2;						\
    x0 &= x3;						\
    x1 &= x2;						\
    x2 ^= y3;						\
    y3 ^= y2;						\
    y2 |= x1;						\
    y1  = y3 & y0;					\
    y2 ^= y1;						\
    y1 ^= y0;						\
    y1 |= x1;						\
    y1 ^= x0;						\
    y0 &= x3;						\
    y0 ^= x2;						\
    y0  = ~y0;						\
  } while (0)

/* S5: 15  5  2 11  4 10  9 12  0  3 14  8 13  6  7  1 */
/* Original single-assignment form:
    t01 = x1  ^ x3;
    t02 = x1  | x3;
    t03 = x0  & t01;
    t04 = x2  ^ t02;
    t05 = t03 ^ t04;
    y0  =     ~ t05;
    t07 = x0  ^ t01;
    t08 = x3  | y0;
    t09 = x1  | t05;
    t10 = x3  ^ t08;
    t11 = x1  | t07;
    t12 = t03 | y0;
    t13 = t07 | t10;
    t14 = t01 ^ t11;
    y2  = t09 ^ t13;
    y1  = t07 ^ t08;
    y3  = t12 ^ t14;
*/
#define SBOX5(x0, x1, x2, x3, y0, y1, y2, y3)	\
  do {							\
    y0  = x1 | x3;					\
    y0 ^= x2;						\
    x2  = x1 ^ x3;					\
    y2  = x0 ^ x2;					\
    x0 &= x2;						\
    y0 ^= x0;						\
    y3  = x1 | y2;					\
    x1 |= y0;						\
    y0  = ~y0;						\
    x0 |= y0;						\
    y3 ^= x2;						\
    y3 ^= x0;						\
    y1  = x3 | y0;					\
    x3 ^= y1;						\
    y1 ^= y2;						\
    y2 |= x3;						\
    y2 ^= x1;						\
  } while (0)

/* S6:  7  2 12  5  8  4  6 11 14  9  1 15 13  3 10  0 */
/* Original single-assignment form:
    t01 = x0  & x3;
    t02 = x1  ^ x2;
    t03 = x0  ^ x3;
    t04 = t01 ^ t02;
    t05 = x1  | x2;
    y1  =     ~ t04;
    t07 = t03 & t05;
    t08 = x1  & y1;
    t09 = x0  | x2;
    t10 = t07 ^ t08;
    t11 = x1  | x3;
    t12 = x2  ^ t11;
    t13 = t09 ^ t10;
    y2  =     ~ t13;
    t15 = y1  & t03;
    y3  = t12 ^ t07;
    t17 = x0  ^ x1;
    t18 = y2  ^ t15;
    y0  = t17 ^ t18;
*/
#define SBOX6(x0, x1, x2, x3, y0, y1, y2, y3)	\
  do {							\
    y0  = x0 ^ x3;					\
    y1  = x0 & x3;					\
    y2  = x0 | x2;					\
    x3 |= x1;						\
    x3 ^= x2;						\
    x0 ^= x1;						\
    y3  = x1 | x2;					\
    x2 ^= x1;						\
    y3 &= y0;						\
    y1 ^= x2;						\
    y1  = ~y1;						\
    y0 &= y1;						\
    x1 &= y1;						\
    x1 ^= y3;						\
    y3 ^= x3;						\
    y2 ^= x1;						\
    y2  = ~y2;						\
    y0 ^= y2;						\
    y0 ^= x0;						\
  } while (0)

/* S7:  1 13 15  0 14  8  2 11  7  4 12 10  9  3  5  6 */
/* Original single-assignment form:
    t01 = x0  & x2;
    t02 =     ~ x3;
    t03 = x0  & t02;
    t04 = x1  | t01;
    t05 = x0  & x1;
    t06 = x2  ^ t04;
    y3  = t03 ^ t06;
    t08 = x2  | y3;
    t09 = x3  | t05;
    t10 = x0  ^ t08;
    t11 = t04 & y3;
    y1  = t09 ^ t10;
    t13 = x1  ^ y1;
    t14 = t01 ^ y1;
    t15 = x2  ^ t05;
    t16 = t11 | t13;
    t17 = t02 | t14;
    y0  = t15 ^ t17;
    y2  = x0  ^ t16;
*/
/* It appears impossible to do this with only 8 registers. We
   recompute t02, and t04 (if we have spare registers, hopefully the
   compiler can recognize them as common subexpressions). */
#define SBOX7(x0, x1, x2, x3, y0, y1, y2, y3)	\
  do {							\
    y0  = x0 & x2;					\
    y3  = x1 | y0; /* t04 */				\
    y3 ^= x2;						\
    y1  = ~x3;     /* t02 */				\
    y1 &= x0;						\
    y3 ^= y1;						\
    y1  = x2 | y3;					\
    y1 ^= x0;						\
    y2  = x0 & x1;					\
    x2 ^= y2;						\
    y2 |= x3;						\
    y1 ^= y2;						\
    y2  = x1 | y0; /* t04 */				\
    y2 &= y3;						\
    x1 ^= y1;						\
    y2 |= x1;						\
    y2 ^= x0;						\
    y0 ^= y1;						\
    x3  = ~x3;     /* t02 */				\
    y0 |= x3;						\
    y0 ^= x2;						\
  } while (0)

/* In-place linear transformation.  */
#define LINEAR_TRANSFORMATION(x0,x1,x2,x3)		 \
  do {                                                   \
    x0 = ROTL32 (13, x0);                    \
    x2 = ROTL32 (3, x2);                     \
    x1 = x1 ^ x0 ^ x2;        \
    x3 = x3 ^ x2 ^ (x0 << 3); \
    x1 = ROTL32 (1, x1);                     \
    x3 = ROTL32 (7, x3);                     \
    x0 = x0 ^ x1 ^ x3;        \
    x2 = x2 ^ x3 ^ (x1 << 7); \
    x0 = ROTL32 (5, x0);                     \
    x2 = ROTL32 (22, x2);                    \
  } while (0)

/* Round inputs are x0,x1,x2,x3 (destroyed), and round outputs are
   y0,y1,y2,y3. */
#define ROUND(which, subkey, x0,x1,x2,x3, y0,y1,y2,y3) \
  do {						       \
    KEYXOR(x0,x1,x2,x3, subkey);		       \
    SBOX##which(x0,x1,x2,x3, y0,y1,y2,y3);	       \
    LINEAR_TRANSFORMATION(y0,y1,y2,y3);		       \
  } while (0)

#if HAVE_NATIVE_64_BIT

#define LINEAR_TRANSFORMATION64(x0,x1,x2,x3)		 \
  do {                                                   \
    x0 = DROTL32 (13, x0);                    \
    x2 = DROTL32 (3, x2);                     \
    x1 = x1 ^ x0 ^ x2;        \
    x3 = x3 ^ x2 ^ DRSHIFT32(3, x0);	    \
    x1 = DROTL32 (1, x1);                     \
    x3 = DROTL32 (7, x3);                     \
    x0 = x0 ^ x1 ^ x3;        \
    x2 = x2 ^ x3 ^ DRSHIFT32(7, x1);	    \
    x0 = DROTL32 (5, x0);                     \
    x2 = DROTL32 (22, x2);                    \
  } while (0)

#define ROUND64(which, subkey, x0,x1,x2,x3, y0,y1,y2,y3) \
  do {						       \
    KEYXOR64(x0,x1,x2,x3, subkey);		       \
    SBOX##which(x0,x1,x2,x3, y0,y1,y2,y3);	       \
    LINEAR_TRANSFORMATION64(y0,y1,y2,y3);		       \
  } while (0)

#endif /* HAVE_NATIVE_64_BIT */

void
serpent_encrypt (const struct serpent_ctx *ctx,
		 size_t length, uint8_t * dst, const uint8_t * src)
{
  assert( !(length % SERPENT_BLOCK_SIZE));
  
#if HAVE_NATIVE_64_BIT
  if (length & SERPENT_BLOCK_SIZE)
#else
  while (length >= SERPENT_BLOCK_SIZE)
#endif
    {
      uint32_t x0,x1,x2,x3, y0,y1,y2,y3;
      unsigned k;

      x0 = LE_READ_UINT32 (src);
      x1 = LE_READ_UINT32 (src + 4);
      x2 = LE_READ_UINT32 (src + 8);
      x3 = LE_READ_UINT32 (src + 12);

      for (k = 0; ; k += 8)
	{
	  ROUND (0, ctx->keys[k+0], x0,x1,x2,x3, y0,y1,y2,y3);
	  ROUND (1, ctx->keys[k+1], y0,y1,y2,y3, x0,x1,x2,x3);
	  ROUND (2, ctx->keys[k+2], x0,x1,x2,x3, y0,y1,y2,y3);
	  ROUND (3, ctx->keys[k+3], y0,y1,y2,y3, x0,x1,x2,x3);
	  ROUND (4, ctx->keys[k+4], x0,x1,x2,x3, y0,y1,y2,y3);
	  ROUND (5, ctx->keys[k+5], y0,y1,y2,y3, x0,x1,x2,x3);
	  ROUND (6, ctx->keys[k+6], x0,x1,x2,x3, y0,y1,y2,y3);
	  if (k == 24)
	    break;
	  ROUND (7, ctx->keys[k+7], y0,y1,y2,y3, x0,x1,x2,x3);
	}

      /* Special final round, using two subkeys. */
      KEYXOR (y0,y1,y2,y3, ctx->keys[31]);
      SBOX7 (y0,y1,y2,y3, x0,x1,x2,x3);
      KEYXOR (x0,x1,x2,x3, ctx->keys[32]);
    
      LE_WRITE_UINT32 (dst, x0);
      LE_WRITE_UINT32 (dst + 4, x1);
      LE_WRITE_UINT32 (dst + 8, x2);
      LE_WRITE_UINT32 (dst + 12, x3);

      src += SERPENT_BLOCK_SIZE;
      dst += SERPENT_BLOCK_SIZE;
      length -= SERPENT_BLOCK_SIZE;
    }
#if HAVE_NATIVE_64_BIT
  FOR_BLOCKS(length, dst, src, 2*SERPENT_BLOCK_SIZE)
    {
      uint64_t x0,x1,x2,x3, y0,y1,y2,y3;
      unsigned k;

      x0 = LE_READ_UINT32 (src);
      x1 = LE_READ_UINT32 (src + 4);
      x2 = LE_READ_UINT32 (src + 8);
      x3 = LE_READ_UINT32 (src + 12);

      x0 <<= 32; x0 |= LE_READ_UINT32 (src + 16);
      x1 <<= 32; x1 |= LE_READ_UINT32 (src + 20);
      x2 <<= 32; x2 |= LE_READ_UINT32 (src + 24);
      x3 <<= 32; x3 |= LE_READ_UINT32 (src + 28);

      for (k = 0; ; k += 8)
	{
	  ROUND64 (0, ctx->keys[k+0], x0,x1,x2,x3, y0,y1,y2,y3);
	  ROUND64 (1, ctx->keys[k+1], y0,y1,y2,y3, x0,x1,x2,x3);
	  ROUND64 (2, ctx->keys[k+2], x0,x1,x2,x3, y0,y1,y2,y3);
	  ROUND64 (3, ctx->keys[k+3], y0,y1,y2,y3, x0,x1,x2,x3);
	  ROUND64 (4, ctx->keys[k+4], x0,x1,x2,x3, y0,y1,y2,y3);
	  ROUND64 (5, ctx->keys[k+5], y0,y1,y2,y3, x0,x1,x2,x3);
	  ROUND64 (6, ctx->keys[k+6], x0,x1,x2,x3, y0,y1,y2,y3);
	  if (k == 24)
	    break;
	  ROUND64 (7, ctx->keys[k+7], y0,y1,y2,y3, x0,x1,x2,x3);
	}

      /* Special final round, using two subkeys. */
      KEYXOR64 (y0,y1,y2,y3, ctx->keys[31]);
      SBOX7 (y0,y1,y2,y3, x0,x1,x2,x3);
      KEYXOR64 (x0,x1,x2,x3, ctx->keys[32]);
    
      LE_WRITE_UINT32 (dst + 16, x0);
      LE_WRITE_UINT32 (dst + 20, x1);
      LE_WRITE_UINT32 (dst + 24, x2);
      LE_WRITE_UINT32 (dst + 28, x3);
      x0 >>= 32; LE_WRITE_UINT32 (dst, x0);
      x1 >>= 32; LE_WRITE_UINT32 (dst + 4, x1);
      x2 >>= 32; LE_WRITE_UINT32 (dst + 8, x2);
      x3 >>= 32; LE_WRITE_UINT32 (dst + 12, x3);
    }
#endif /* HAVE_NATIVE_64_BIT */
}