Coverage Report

Created: 2024-11-21 07:03

/src/nss-nspr/nss/lib/freebl/mpi/mpmontg.c
Line
Count
Source (jump to first uncovered line)
1
/* This Source Code Form is subject to the terms of the Mozilla Public
2
 * License, v. 2.0. If a copy of the MPL was not distributed with this
3
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
4
5
/* This file implements moduluar exponentiation using Montgomery's
6
 * method for modular reduction.  This file implements the method
7
 * described as "Improvement 2" in the paper "A Cryptogrpahic Library for
8
 * the Motorola DSP56000" by Stephen R. Dusse' and Burton S. Kaliski Jr.
9
 * published in "Advances in Cryptology: Proceedings of EUROCRYPT '90"
10
 * "Lecture Notes in Computer Science" volume 473, 1991, pg 230-244,
11
 * published by Springer Verlag.
12
 */
13
14
#define MP_USING_CACHE_SAFE_MOD_EXP 1
15
#include <string.h>
16
#include "mpi-priv.h"
17
#include "mplogic.h"
18
#include "mpprime.h"
19
#ifdef MP_USING_MONT_MULF
20
#include "montmulf.h"
21
#endif
22
#include <stddef.h> /* ptrdiff_t */
23
#include <assert.h>
24
25
#define STATIC
26
27
0
#define MAX_ODD_INTS 32 /* 2 ** (WINDOW_BITS - 1) */
28
29
/*! computes T = REDC(T), 2^b == R
30
    \param T < RN
31
*/
32
mp_err
33
s_mp_redc(mp_int *T, mp_mont_modulus *mmm)
34
753k
{
35
753k
    mp_err res;
36
753k
    mp_size i;
37
38
753k
    i = (MP_USED(&mmm->N) << 1) + 1;
39
753k
    MP_CHECKOK(s_mp_pad(T, i));
40
56.7M
    for (i = 0; i < MP_USED(&mmm->N); ++i) {
41
56.0M
        mp_digit m_i = MP_DIGIT(T, i) * mmm->n0prime;
42
        /* T += N * m_i * (MP_RADIX ** i); */
43
56.0M
        s_mp_mul_d_add_offset(&mmm->N, m_i, T, i);
44
56.0M
    }
45
753k
    s_mp_clamp(T);
46
47
    /* T /= R */
48
753k
    s_mp_rshd(T, MP_USED(&mmm->N));
49
50
753k
    if (s_mp_cmp(T, &mmm->N) >= 0) {
51
        /* T = T - N */
52
41.1k
        MP_CHECKOK(s_mp_sub(T, &mmm->N));
53
41.1k
#ifdef DEBUG
54
41.1k
        if (mp_cmp(T, &mmm->N) >= 0) {
55
0
            res = MP_UNDEF;
56
0
            goto CLEANUP;
57
0
        }
58
41.1k
#endif
59
41.1k
    }
60
753k
    res = MP_OKAY;
61
753k
CLEANUP:
62
753k
    return res;
63
753k
}
64
65
#if !defined(MP_MONT_USE_MP_MUL)
66
67
/*! c <- REDC( a * b ) mod N
68
    \param a < N  i.e. "reduced"
69
    \param b < N  i.e. "reduced"
70
    \param mmm modulus N and n0' of N
71
*/
72
mp_err
73
s_mp_mul_mont(const mp_int *a, const mp_int *b, mp_int *c,
74
              mp_mont_modulus *mmm)
75
138k
{
76
138k
    mp_digit *pb;
77
138k
    mp_digit m_i;
78
138k
    mp_err res;
79
138k
    mp_size ib; /* "index b": index of current digit of B */
80
138k
    mp_size useda, usedb;
81
82
138k
    ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
83
84
138k
    if (MP_USED(a) < MP_USED(b)) {
85
4.07k
        const mp_int *xch = b; /* switch a and b, to do fewer outer loops */
86
4.07k
        b = a;
87
4.07k
        a = xch;
88
4.07k
    }
89
90
138k
    MP_USED(c) = 1;
91
138k
    MP_DIGIT(c, 0) = 0;
92
138k
    ib = (MP_USED(&mmm->N) << 1) + 1;
93
138k
    if ((res = s_mp_pad(c, ib)) != MP_OKAY)
94
0
        goto CLEANUP;
95
96
138k
    useda = MP_USED(a);
97
138k
    pb = MP_DIGITS(b);
98
138k
    s_mpv_mul_d(MP_DIGITS(a), useda, *pb++, MP_DIGITS(c));
99
138k
    s_mp_setz(MP_DIGITS(c) + useda + 1, ib - (useda + 1));
100
138k
    m_i = MP_DIGIT(c, 0) * mmm->n0prime;
101
138k
    s_mp_mul_d_add_offset(&mmm->N, m_i, c, 0);
102
103
    /* Outer loop:  Digits of b */
104
138k
    usedb = MP_USED(b);
105
9.92M
    for (ib = 1; ib < usedb; ib++) {
106
9.78M
        mp_digit b_i = *pb++;
107
108
        /* Inner product:  Digits of a */
109
9.78M
        if (b_i)
110
9.78M
            s_mpv_mul_d_add_prop(MP_DIGITS(a), useda, b_i, MP_DIGITS(c) + ib);
111
9.78M
        m_i = MP_DIGIT(c, ib) * mmm->n0prime;
112
9.78M
        s_mp_mul_d_add_offset(&mmm->N, m_i, c, ib);
113
9.78M
    }
114
138k
    if (usedb < MP_USED(&mmm->N)) {
115
45.0k
        for (usedb = MP_USED(&mmm->N); ib < usedb; ++ib) {
116
25.2k
            m_i = MP_DIGIT(c, ib) * mmm->n0prime;
117
25.2k
            s_mp_mul_d_add_offset(&mmm->N, m_i, c, ib);
118
25.2k
        }
119
19.7k
    }
120
138k
    s_mp_clamp(c);
121
138k
    s_mp_rshd(c, MP_USED(&mmm->N)); /* c /= R */
122
138k
    if (s_mp_cmp(c, &mmm->N) >= 0) {
123
5.41k
        MP_CHECKOK(s_mp_sub(c, &mmm->N));
124
5.41k
    }
125
138k
    res = MP_OKAY;
126
127
138k
CLEANUP:
128
138k
    return res;
129
138k
}
130
#endif
131
132
mp_err
133
mp_to_mont(const mp_int *x, const mp_int *N, mp_int *xMont)
134
1.11k
{
135
1.11k
    mp_err res;
136
137
    /* xMont = x * R mod N   where  N is modulus */
138
1.11k
    if (x != xMont) {
139
580
        MP_CHECKOK(mp_copy(x, xMont));
140
580
    }
141
1.11k
    MP_CHECKOK(s_mp_lshd(xMont, MP_USED(N))); /* xMont = x << b */
142
1.11k
    MP_CHECKOK(mp_div(xMont, N, 0, xMont));   /*         mod N */
143
1.11k
CLEANUP:
144
1.11k
    return res;
145
1.11k
}
146
147
mp_digit
148
mp_calculate_mont_n0i(const mp_int *N)
149
582
{
150
582
    return 0 - s_mp_invmod_radix(MP_DIGIT(N, 0));
151
582
}
152
153
#ifdef MP_USING_MONT_MULF
154
155
/* the floating point multiply is already cache safe,
156
 * don't turn on cache safe unless we specifically
157
 * force it */
158
#ifndef MP_FORCE_CACHE_SAFE
159
#undef MP_USING_CACHE_SAFE_MOD_EXP
160
#endif
161
162
unsigned int mp_using_mont_mulf = 1;
163
164
/* computes montgomery square of the integer in mResult */
165
#define SQR                                              \
166
    conv_i32_to_d32_and_d16(dm1, d16Tmp, mResult, nLen); \
167
    mont_mulf_noconv(mResult, dm1, d16Tmp,               \
168
                     dTmp, dn, MP_DIGITS(modulus), nLen, dn0)
169
170
/* computes montgomery product of x and the integer in mResult */
171
#define MUL(x)                                   \
172
    conv_i32_to_d32(dm1, mResult, nLen);         \
173
    mont_mulf_noconv(mResult, dm1, oddPowers[x], \
174
                     dTmp, dn, MP_DIGITS(modulus), nLen, dn0)
175
176
/* Do modular exponentiation using floating point multiply code. */
177
mp_err
178
mp_exptmod_f(const mp_int *montBase,
179
             const mp_int *exponent,
180
             const mp_int *modulus,
181
             mp_int *result,
182
             mp_mont_modulus *mmm,
183
             int nLen,
184
             mp_size bits_in_exponent,
185
             mp_size window_bits,
186
             mp_size odd_ints)
187
{
188
    mp_digit *mResult;
189
    double *dBuf = 0, *dm1, *dn, *dSqr, *d16Tmp, *dTmp;
190
    double dn0;
191
    mp_size i;
192
    mp_err res;
193
    int expOff;
194
    int dSize = 0, oddPowSize, dTmpSize;
195
    mp_int accum1;
196
    double *oddPowers[MAX_ODD_INTS];
197
198
    /* function for computing n0prime only works if n0 is odd */
199
200
    MP_DIGITS(&accum1) = 0;
201
202
    for (i = 0; i < MAX_ODD_INTS; ++i)
203
        oddPowers[i] = 0;
204
205
    MP_CHECKOK(mp_init_size(&accum1, 3 * nLen + 2));
206
207
    mp_set(&accum1, 1);
208
    MP_CHECKOK(mp_to_mont(&accum1, &(mmm->N), &accum1));
209
    MP_CHECKOK(s_mp_pad(&accum1, nLen));
210
211
    oddPowSize = 2 * nLen + 1;
212
    dTmpSize = 2 * oddPowSize;
213
    dSize = sizeof(double) * (nLen * 4 + 1 +
214
                              ((odd_ints + 1) * oddPowSize) + dTmpSize);
215
    dBuf = malloc(dSize);
216
    if (!dBuf) {
217
        res = MP_MEM;
218
        goto CLEANUP;
219
    }
220
    dm1 = dBuf;           /* array of d32 */
221
    dn = dBuf + nLen;     /* array of d32 */
222
    dSqr = dn + nLen;     /* array of d32 */
223
    d16Tmp = dSqr + nLen; /* array of d16 */
224
    dTmp = d16Tmp + oddPowSize;
225
226
    for (i = 0; i < odd_ints; ++i) {
227
        oddPowers[i] = dTmp;
228
        dTmp += oddPowSize;
229
    }
230
    mResult = (mp_digit *)(dTmp + dTmpSize); /* size is nLen + 1 */
231
232
    /* Make dn and dn0 */
233
    conv_i32_to_d32(dn, MP_DIGITS(modulus), nLen);
234
    dn0 = (double)(mmm->n0prime & 0xffff);
235
236
    /* Make dSqr */
237
    conv_i32_to_d32_and_d16(dm1, oddPowers[0], MP_DIGITS(montBase), nLen);
238
    mont_mulf_noconv(mResult, dm1, oddPowers[0],
239
                     dTmp, dn, MP_DIGITS(modulus), nLen, dn0);
240
    conv_i32_to_d32(dSqr, mResult, nLen);
241
242
    for (i = 1; i < odd_ints; ++i) {
243
        mont_mulf_noconv(mResult, dSqr, oddPowers[i - 1],
244
                         dTmp, dn, MP_DIGITS(modulus), nLen, dn0);
245
        conv_i32_to_d16(oddPowers[i], mResult, nLen);
246
    }
247
248
    s_mp_copy(MP_DIGITS(&accum1), mResult, nLen); /* from, to, len */
249
250
    for (expOff = bits_in_exponent - window_bits; expOff >= 0; expOff -= window_bits) {
251
        mp_size smallExp;
252
        MP_CHECKOK(mpl_get_bits(exponent, expOff, window_bits));
253
        smallExp = (mp_size)res;
254
255
        if (window_bits == 1) {
256
            if (!smallExp) {
257
                SQR;
258
            } else if (smallExp & 1) {
259
                SQR;
260
                MUL(0);
261
            } else {
262
                abort();
263
            }
264
        } else if (window_bits == 4) {
265
            if (!smallExp) {
266
                SQR;
267
                SQR;
268
                SQR;
269
                SQR;
270
            } else if (smallExp & 1) {
271
                SQR;
272
                SQR;
273
                SQR;
274
                SQR;
275
                MUL(smallExp / 2);
276
            } else if (smallExp & 2) {
277
                SQR;
278
                SQR;
279
                SQR;
280
                MUL(smallExp / 4);
281
                SQR;
282
            } else if (smallExp & 4) {
283
                SQR;
284
                SQR;
285
                MUL(smallExp / 8);
286
                SQR;
287
                SQR;
288
            } else if (smallExp & 8) {
289
                SQR;
290
                MUL(smallExp / 16);
291
                SQR;
292
                SQR;
293
                SQR;
294
            } else {
295
                abort();
296
            }
297
        } else if (window_bits == 5) {
298
            if (!smallExp) {
299
                SQR;
300
                SQR;
301
                SQR;
302
                SQR;
303
                SQR;
304
            } else if (smallExp & 1) {
305
                SQR;
306
                SQR;
307
                SQR;
308
                SQR;
309
                SQR;
310
                MUL(smallExp / 2);
311
            } else if (smallExp & 2) {
312
                SQR;
313
                SQR;
314
                SQR;
315
                SQR;
316
                MUL(smallExp / 4);
317
                SQR;
318
            } else if (smallExp & 4) {
319
                SQR;
320
                SQR;
321
                SQR;
322
                MUL(smallExp / 8);
323
                SQR;
324
                SQR;
325
            } else if (smallExp & 8) {
326
                SQR;
327
                SQR;
328
                MUL(smallExp / 16);
329
                SQR;
330
                SQR;
331
                SQR;
332
            } else if (smallExp & 0x10) {
333
                SQR;
334
                MUL(smallExp / 32);
335
                SQR;
336
                SQR;
337
                SQR;
338
                SQR;
339
            } else {
340
                abort();
341
            }
342
        } else if (window_bits == 6) {
343
            if (!smallExp) {
344
                SQR;
345
                SQR;
346
                SQR;
347
                SQR;
348
                SQR;
349
                SQR;
350
            } else if (smallExp & 1) {
351
                SQR;
352
                SQR;
353
                SQR;
354
                SQR;
355
                SQR;
356
                SQR;
357
                MUL(smallExp / 2);
358
            } else if (smallExp & 2) {
359
                SQR;
360
                SQR;
361
                SQR;
362
                SQR;
363
                SQR;
364
                MUL(smallExp / 4);
365
                SQR;
366
            } else if (smallExp & 4) {
367
                SQR;
368
                SQR;
369
                SQR;
370
                SQR;
371
                MUL(smallExp / 8);
372
                SQR;
373
                SQR;
374
            } else if (smallExp & 8) {
375
                SQR;
376
                SQR;
377
                SQR;
378
                MUL(smallExp / 16);
379
                SQR;
380
                SQR;
381
                SQR;
382
            } else if (smallExp & 0x10) {
383
                SQR;
384
                SQR;
385
                MUL(smallExp / 32);
386
                SQR;
387
                SQR;
388
                SQR;
389
                SQR;
390
            } else if (smallExp & 0x20) {
391
                SQR;
392
                MUL(smallExp / 64);
393
                SQR;
394
                SQR;
395
                SQR;
396
                SQR;
397
                SQR;
398
            } else {
399
                abort();
400
            }
401
        } else {
402
            abort();
403
        }
404
    }
405
406
    s_mp_copy(mResult, MP_DIGITS(&accum1), nLen); /* from, to, len */
407
408
    res = s_mp_redc(&accum1, mmm);
409
    mp_exch(&accum1, result);
410
411
CLEANUP:
412
    mp_clear(&accum1);
413
    if (dBuf) {
414
        if (dSize)
415
            memset(dBuf, 0, dSize);
416
        free(dBuf);
417
    }
418
419
    return res;
420
}
421
#undef SQR
422
#undef MUL
423
#endif
424
425
#define SQR(a, b)             \
426
0
    MP_CHECKOK(mp_sqr(a, b)); \
427
0
    MP_CHECKOK(s_mp_redc(b, mmm))
428
429
#if defined(MP_MONT_USE_MP_MUL)
430
#define MUL(x, a, b)                           \
431
    MP_CHECKOK(mp_mul(a, oddPowers + (x), b)); \
432
    MP_CHECKOK(s_mp_redc(b, mmm))
433
#else
434
#define MUL(x, a, b) \
435
0
    MP_CHECKOK(s_mp_mul_mont(a, oddPowers + (x), b, mmm))
436
#endif
437
438
#define SWAPPA  \
439
0
    ptmp = pa1; \
440
0
    pa1 = pa2;  \
441
0
    pa2 = ptmp
442
443
/* Do modular exponentiation using integer multiply code. */
444
mp_err
445
mp_exptmod_i(const mp_int *montBase,
446
             const mp_int *exponent,
447
             const mp_int *modulus,
448
             mp_int *result,
449
             mp_mont_modulus *mmm,
450
             int nLen,
451
             mp_size bits_in_exponent,
452
             mp_size window_bits,
453
             mp_size odd_ints)
454
0
{
455
0
    mp_int *pa1, *pa2, *ptmp;
456
0
    mp_size i;
457
0
    mp_err res;
458
0
    int expOff;
459
0
    mp_int accum1, accum2, power2, oddPowers[MAX_ODD_INTS];
460
461
    /* power2 = base ** 2; oddPowers[i] = base ** (2*i + 1); */
462
    /* oddPowers[i] = base ** (2*i + 1); */
463
464
0
    MP_DIGITS(&accum1) = 0;
465
0
    MP_DIGITS(&accum2) = 0;
466
0
    MP_DIGITS(&power2) = 0;
467
0
    for (i = 0; i < MAX_ODD_INTS; ++i) {
468
0
        MP_DIGITS(oddPowers + i) = 0;
469
0
    }
470
471
0
    MP_CHECKOK(mp_init_size(&accum1, 3 * nLen + 2));
472
0
    MP_CHECKOK(mp_init_size(&accum2, 3 * nLen + 2));
473
474
0
    MP_CHECKOK(mp_init_copy(&oddPowers[0], montBase));
475
476
0
    MP_CHECKOK(mp_init_size(&power2, nLen + 2 * MP_USED(montBase) + 2));
477
0
    MP_CHECKOK(mp_sqr(montBase, &power2)); /* power2 = montBase ** 2 */
478
0
    MP_CHECKOK(s_mp_redc(&power2, mmm));
479
480
0
    for (i = 1; i < odd_ints; ++i) {
481
0
        MP_CHECKOK(mp_init_size(oddPowers + i, nLen + 2 * MP_USED(&power2) + 2));
482
0
        MP_CHECKOK(mp_mul(oddPowers + (i - 1), &power2, oddPowers + i));
483
0
        MP_CHECKOK(s_mp_redc(oddPowers + i, mmm));
484
0
    }
485
486
    /* set accumulator to montgomery residue of 1 */
487
0
    mp_set(&accum1, 1);
488
0
    MP_CHECKOK(mp_to_mont(&accum1, &(mmm->N), &accum1));
489
0
    pa1 = &accum1;
490
0
    pa2 = &accum2;
491
492
0
    for (expOff = bits_in_exponent - window_bits; expOff >= 0; expOff -= window_bits) {
493
0
        mp_size smallExp;
494
0
        MP_CHECKOK(mpl_get_bits(exponent, expOff, window_bits));
495
0
        smallExp = (mp_size)res;
496
497
0
        if (window_bits == 1) {
498
0
            if (!smallExp) {
499
0
                SQR(pa1, pa2);
500
0
                SWAPPA;
501
0
            } else if (smallExp & 1) {
502
0
                SQR(pa1, pa2);
503
0
                MUL(0, pa2, pa1);
504
0
            } else {
505
0
                abort();
506
0
            }
507
0
        } else if (window_bits == 4) {
508
0
            if (!smallExp) {
509
0
                SQR(pa1, pa2);
510
0
                SQR(pa2, pa1);
511
0
                SQR(pa1, pa2);
512
0
                SQR(pa2, pa1);
513
0
            } else if (smallExp & 1) {
514
0
                SQR(pa1, pa2);
515
0
                SQR(pa2, pa1);
516
0
                SQR(pa1, pa2);
517
0
                SQR(pa2, pa1);
518
0
                MUL(smallExp / 2, pa1, pa2);
519
0
                SWAPPA;
520
0
            } else if (smallExp & 2) {
521
0
                SQR(pa1, pa2);
522
0
                SQR(pa2, pa1);
523
0
                SQR(pa1, pa2);
524
0
                MUL(smallExp / 4, pa2, pa1);
525
0
                SQR(pa1, pa2);
526
0
                SWAPPA;
527
0
            } else if (smallExp & 4) {
528
0
                SQR(pa1, pa2);
529
0
                SQR(pa2, pa1);
530
0
                MUL(smallExp / 8, pa1, pa2);
531
0
                SQR(pa2, pa1);
532
0
                SQR(pa1, pa2);
533
0
                SWAPPA;
534
0
            } else if (smallExp & 8) {
535
0
                SQR(pa1, pa2);
536
0
                MUL(smallExp / 16, pa2, pa1);
537
0
                SQR(pa1, pa2);
538
0
                SQR(pa2, pa1);
539
0
                SQR(pa1, pa2);
540
0
                SWAPPA;
541
0
            } else {
542
0
                abort();
543
0
            }
544
0
        } else if (window_bits == 5) {
545
0
            if (!smallExp) {
546
0
                SQR(pa1, pa2);
547
0
                SQR(pa2, pa1);
548
0
                SQR(pa1, pa2);
549
0
                SQR(pa2, pa1);
550
0
                SQR(pa1, pa2);
551
0
                SWAPPA;
552
0
            } else if (smallExp & 1) {
553
0
                SQR(pa1, pa2);
554
0
                SQR(pa2, pa1);
555
0
                SQR(pa1, pa2);
556
0
                SQR(pa2, pa1);
557
0
                SQR(pa1, pa2);
558
0
                MUL(smallExp / 2, pa2, pa1);
559
0
            } else if (smallExp & 2) {
560
0
                SQR(pa1, pa2);
561
0
                SQR(pa2, pa1);
562
0
                SQR(pa1, pa2);
563
0
                SQR(pa2, pa1);
564
0
                MUL(smallExp / 4, pa1, pa2);
565
0
                SQR(pa2, pa1);
566
0
            } else if (smallExp & 4) {
567
0
                SQR(pa1, pa2);
568
0
                SQR(pa2, pa1);
569
0
                SQR(pa1, pa2);
570
0
                MUL(smallExp / 8, pa2, pa1);
571
0
                SQR(pa1, pa2);
572
0
                SQR(pa2, pa1);
573
0
            } else if (smallExp & 8) {
574
0
                SQR(pa1, pa2);
575
0
                SQR(pa2, pa1);
576
0
                MUL(smallExp / 16, pa1, pa2);
577
0
                SQR(pa2, pa1);
578
0
                SQR(pa1, pa2);
579
0
                SQR(pa2, pa1);
580
0
            } else if (smallExp & 0x10) {
581
0
                SQR(pa1, pa2);
582
0
                MUL(smallExp / 32, pa2, pa1);
583
0
                SQR(pa1, pa2);
584
0
                SQR(pa2, pa1);
585
0
                SQR(pa1, pa2);
586
0
                SQR(pa2, pa1);
587
0
            } else {
588
0
                abort();
589
0
            }
590
0
        } else if (window_bits == 6) {
591
0
            if (!smallExp) {
592
0
                SQR(pa1, pa2);
593
0
                SQR(pa2, pa1);
594
0
                SQR(pa1, pa2);
595
0
                SQR(pa2, pa1);
596
0
                SQR(pa1, pa2);
597
0
                SQR(pa2, pa1);
598
0
            } else if (smallExp & 1) {
599
0
                SQR(pa1, pa2);
600
0
                SQR(pa2, pa1);
601
0
                SQR(pa1, pa2);
602
0
                SQR(pa2, pa1);
603
0
                SQR(pa1, pa2);
604
0
                SQR(pa2, pa1);
605
0
                MUL(smallExp / 2, pa1, pa2);
606
0
                SWAPPA;
607
0
            } else if (smallExp & 2) {
608
0
                SQR(pa1, pa2);
609
0
                SQR(pa2, pa1);
610
0
                SQR(pa1, pa2);
611
0
                SQR(pa2, pa1);
612
0
                SQR(pa1, pa2);
613
0
                MUL(smallExp / 4, pa2, pa1);
614
0
                SQR(pa1, pa2);
615
0
                SWAPPA;
616
0
            } else if (smallExp & 4) {
617
0
                SQR(pa1, pa2);
618
0
                SQR(pa2, pa1);
619
0
                SQR(pa1, pa2);
620
0
                SQR(pa2, pa1);
621
0
                MUL(smallExp / 8, pa1, pa2);
622
0
                SQR(pa2, pa1);
623
0
                SQR(pa1, pa2);
624
0
                SWAPPA;
625
0
            } else if (smallExp & 8) {
626
0
                SQR(pa1, pa2);
627
0
                SQR(pa2, pa1);
628
0
                SQR(pa1, pa2);
629
0
                MUL(smallExp / 16, pa2, pa1);
630
0
                SQR(pa1, pa2);
631
0
                SQR(pa2, pa1);
632
0
                SQR(pa1, pa2);
633
0
                SWAPPA;
634
0
            } else if (smallExp & 0x10) {
635
0
                SQR(pa1, pa2);
636
0
                SQR(pa2, pa1);
637
0
                MUL(smallExp / 32, pa1, pa2);
638
0
                SQR(pa2, pa1);
639
0
                SQR(pa1, pa2);
640
0
                SQR(pa2, pa1);
641
0
                SQR(pa1, pa2);
642
0
                SWAPPA;
643
0
            } else if (smallExp & 0x20) {
644
0
                SQR(pa1, pa2);
645
0
                MUL(smallExp / 64, pa2, pa1);
646
0
                SQR(pa1, pa2);
647
0
                SQR(pa2, pa1);
648
0
                SQR(pa1, pa2);
649
0
                SQR(pa2, pa1);
650
0
                SQR(pa1, pa2);
651
0
                SWAPPA;
652
0
            } else {
653
0
                abort();
654
0
            }
655
0
        } else {
656
0
            abort();
657
0
        }
658
0
    }
659
660
0
    res = s_mp_redc(pa1, mmm);
661
0
    mp_exch(pa1, result);
662
663
0
CLEANUP:
664
0
    mp_clear(&accum1);
665
0
    mp_clear(&accum2);
666
0
    mp_clear(&power2);
667
0
    for (i = 0; i < odd_ints; ++i) {
668
0
        mp_clear(oddPowers + i);
669
0
    }
670
0
    return res;
671
0
}
672
#undef SQR
673
#undef MUL
674
675
#ifdef MP_USING_CACHE_SAFE_MOD_EXP
676
unsigned int mp_using_cache_safe_exp = 1;
677
#endif
678
679
mp_err
680
mp_set_safe_modexp(int value)
681
0
{
682
0
#ifdef MP_USING_CACHE_SAFE_MOD_EXP
683
0
    mp_using_cache_safe_exp = value;
684
0
    return MP_OKAY;
685
#else
686
    if (value == 0) {
687
        return MP_OKAY;
688
    }
689
    return MP_BADARG;
690
#endif
691
0
}
692
693
#ifdef MP_USING_CACHE_SAFE_MOD_EXP
694
58.5k
#define WEAVE_WORD_SIZE 4
695
696
/*
697
 * mpi_to_weave takes an array of bignums, a matrix in which each bignum
698
 * occupies all the columns of a row, and transposes it into a matrix in
699
 * which each bignum occupies a column of every row.  The first row of the
700
 * input matrix becomes the first column of the output matrix.  The n'th
701
 * row of input becomes the n'th column of output.  The input data is said
702
 * to be "interleaved" or "woven" into the output matrix.
703
 *
704
 * The array of bignums is left in this woven form.  Each time a single
705
 * bignum value is needed, it is recreated by fetching the n'th column,
706
 * forming a single row which is the new bignum.
707
 *
708
 * The purpose of this interleaving is make it impossible to determine which
709
 * of the bignums is being used in any one operation by examining the pattern
710
 * of cache misses.
711
 *
712
 * The weaving function does not transpose the entire input matrix in one call.
713
 * It transposes 4 rows of mp_ints into their respective columns of output.
714
 *
715
 * This implementation treats each mp_int bignum as an array of mp_digits,
716
 * It stores those bytes as a column of mp_digits in the output matrix.  It
717
 * doesn't care if the machine uses big-endian or little-endian byte ordering
718
 * within mp_digits.
719
 *
720
 * "bignums" is an array of mp_ints.
721
 * It points to four rows, four mp_ints, a subset of a larger array of mp_ints.
722
 *
723
 * "weaved" is the weaved output matrix.
724
 * The first byte of bignums[0] is stored in weaved[0].
725
 *
726
 * "nBignums" is the total number of bignums in the array of which "bignums"
727
 * is a part.
728
 *
729
 * "nDigits" is the size in mp_digits of each mp_int in the "bignums" array.
730
 * mp_ints that use less than nDigits digits are logically padded with zeros
731
 * while being stored in the weaved array.
732
 */
733
mp_err
734
mpi_to_weave(const mp_int *bignums,
735
             mp_digit *weaved,
736
             mp_size nDigits,  /* in each mp_int of input */
737
             mp_size nBignums) /* in the entire source array */
738
4.66k
{
739
4.66k
    mp_size i;
740
4.66k
    mp_digit *endDest = weaved + (nDigits * nBignums);
741
742
23.3k
    for (i = 0; i < WEAVE_WORD_SIZE; i++) {
743
18.6k
        mp_size used = MP_USED(&bignums[i]);
744
18.6k
        mp_digit *pSrc = MP_DIGITS(&bignums[i]);
745
18.6k
        mp_digit *endSrc = pSrc + used;
746
18.6k
        mp_digit *pDest = weaved + i;
747
748
18.6k
        ARGCHK(MP_SIGN(&bignums[i]) == MP_ZPOS, MP_BADARG);
749
18.6k
        ARGCHK(used <= nDigits, MP_BADARG);
750
751
944k
        for (; pSrc < endSrc; pSrc++) {
752
926k
            *pDest = *pSrc;
753
926k
            pDest += nBignums;
754
926k
        }
755
22.2k
        while (pDest < endDest) {
756
3.62k
            *pDest = 0;
757
3.62k
            pDest += nBignums;
758
3.62k
        }
759
18.6k
    }
760
761
4.66k
    return MP_OKAY;
762
4.66k
}
763
764
/*
765
 * These functions return 0xffffffff if the output is true, and 0 otherwise.
766
 */
767
584M
#define CONST_TIME_MSB(x) (0L - ((x) >> (8 * sizeof(x) - 1)))
768
584M
#define CONST_TIME_EQ_Z(x) CONST_TIME_MSB(~(x) & ((x)-1))
769
584M
#define CONST_TIME_EQ(a, b) CONST_TIME_EQ_Z((a) ^ (b))
770
771
/* Reverse the operation above for one mp_int.
772
 * Reconstruct one mp_int from its column in the weaved array.
773
 * Every read accesses every element of the weaved array, in order to
774
 * avoid timing attacks based on patterns of memory accesses.
775
 */
776
mp_err
777
weave_to_mpi(mp_int *a,              /* out, result */
778
             const mp_digit *weaved, /* in, byte matrix */
779
             mp_size index,          /* which column to read */
780
             mp_size nDigits,        /* number of mp_digits in each bignum */
781
             mp_size nBignums)       /* width of the matrix */
782
136k
{
783
    /* these are indices, but need to be the same size as mp_digit
784
     * because of the CONST_TIME operations */
785
136k
    mp_digit i, j;
786
136k
    mp_digit d;
787
136k
    mp_digit *pDest = MP_DIGITS(a);
788
789
136k
    MP_SIGN(a) = MP_ZPOS;
790
136k
    MP_USED(a) = nDigits;
791
792
136k
    assert(weaved != NULL);
793
794
    /* Fetch the proper column in constant time, indexing over the whole array */
795
9.98M
    for (i = 0; i < nDigits; ++i) {
796
9.84M
        d = 0;
797
594M
        for (j = 0; j < nBignums; ++j) {
798
584M
            d |= weaved[i * nBignums + j] & CONST_TIME_EQ(j, index);
799
584M
        }
800
9.84M
        pDest[i] = d;
801
9.84M
    }
802
803
136k
    s_mp_clamp(a);
804
136k
    return MP_OKAY;
805
136k
}
806
807
#define SQR(a, b)             \
808
752k
    MP_CHECKOK(mp_sqr(a, b)); \
809
752k
    MP_CHECKOK(s_mp_redc(b, mmm))
810
811
#if defined(MP_MONT_USE_MP_MUL)
812
#define MUL_NOWEAVE(x, a, b)     \
813
    MP_CHECKOK(mp_mul(a, x, b)); \
814
    MP_CHECKOK(s_mp_redc(b, mmm))
815
#else
816
#define MUL_NOWEAVE(x, a, b) \
817
138k
    MP_CHECKOK(s_mp_mul_mont(a, x, b, mmm))
818
#endif
819
820
#define MUL(x, a, b)                                               \
821
129k
    MP_CHECKOK(weave_to_mpi(&tmp, powers, (x), nLen, num_powers)); \
822
129k
    MUL_NOWEAVE(&tmp, a, b)
823
824
#define SWAPPA  \
825
116k
    ptmp = pa1; \
826
116k
    pa1 = pa2;  \
827
116k
    pa2 = ptmp
828
531
#define MP_ALIGN(x, y) ((((ptrdiff_t)(x)) + ((y)-1)) & (((ptrdiff_t)0) - (y)))
829
830
/* Do modular exponentiation using integer multiply code. */
831
mp_err
832
mp_exptmod_safe_i(const mp_int *montBase,
833
                  const mp_int *exponent,
834
                  const mp_int *modulus,
835
                  mp_int *result,
836
                  mp_mont_modulus *mmm,
837
                  int nLen,
838
                  mp_size bits_in_exponent,
839
                  mp_size window_bits,
840
                  mp_size num_powers)
841
580
{
842
580
    mp_int *pa1, *pa2, *ptmp;
843
580
    mp_size i;
844
580
    mp_size first_window;
845
580
    mp_err res;
846
580
    int expOff;
847
580
    mp_int accum1, accum2, accum[WEAVE_WORD_SIZE];
848
580
    mp_int tmp;
849
580
    mp_digit *powersArray = NULL;
850
580
    mp_digit *powers = NULL;
851
852
580
    MP_DIGITS(&accum1) = 0;
853
580
    MP_DIGITS(&accum2) = 0;
854
580
    MP_DIGITS(&accum[0]) = 0;
855
580
    MP_DIGITS(&accum[1]) = 0;
856
580
    MP_DIGITS(&accum[2]) = 0;
857
580
    MP_DIGITS(&accum[3]) = 0;
858
580
    MP_DIGITS(&tmp) = 0;
859
860
    /* grab the first window value. This allows us to preload accumulator1
861
     * and save a conversion, some squares and a multiple*/
862
580
    MP_CHECKOK(mpl_get_bits(exponent,
863
580
                            bits_in_exponent - window_bits, window_bits));
864
580
    first_window = (mp_size)res;
865
866
580
    MP_CHECKOK(mp_init_size(&accum1, 3 * nLen + 2));
867
580
    MP_CHECKOK(mp_init_size(&accum2, 3 * nLen + 2));
868
869
    /* build the first WEAVE_WORD powers inline */
870
    /* if WEAVE_WORD_SIZE is not 4, this code will have to change */
871
580
    if (num_powers > 2) {
872
531
        MP_CHECKOK(mp_init_size(&accum[0], 3 * nLen + 2));
873
531
        MP_CHECKOK(mp_init_size(&accum[1], 3 * nLen + 2));
874
531
        MP_CHECKOK(mp_init_size(&accum[2], 3 * nLen + 2));
875
531
        MP_CHECKOK(mp_init_size(&accum[3], 3 * nLen + 2));
876
531
        mp_set(&accum[0], 1);
877
531
        MP_CHECKOK(mp_to_mont(&accum[0], &(mmm->N), &accum[0]));
878
531
        MP_CHECKOK(mp_copy(montBase, &accum[1]));
879
1.06k
        SQR(montBase, &accum[2]);
880
531
        MUL_NOWEAVE(montBase, &accum[2], &accum[3]);
881
531
        powersArray = (mp_digit *)malloc(num_powers * (nLen * sizeof(mp_digit) + 1));
882
531
        if (!powersArray) {
883
0
            res = MP_MEM;
884
0
            goto CLEANUP;
885
0
        }
886
        /* powers[i] = base ** (i); */
887
531
        powers = (mp_digit *)MP_ALIGN(powersArray, num_powers);
888
531
        MP_CHECKOK(mpi_to_weave(accum, powers, nLen, num_powers));
889
531
        if (first_window < 4) {
890
204
            MP_CHECKOK(mp_copy(&accum[first_window], &accum1));
891
204
            first_window = num_powers;
892
204
        }
893
531
    } else {
894
49
        if (first_window == 0) {
895
1
            mp_set(&accum1, 1);
896
1
            MP_CHECKOK(mp_to_mont(&accum1, &(mmm->N), &accum1));
897
48
        } else {
898
            /* assert first_window == 1? */
899
48
            MP_CHECKOK(mp_copy(montBase, &accum1));
900
48
        }
901
49
    }
902
903
    /*
904
     * calculate all the powers in the powers array.
905
     * this adds 2**(k-1)-2 square operations over just calculating the
906
     * odd powers where k is the window size in the two other mp_modexpt
907
     * implementations in this file. We will get some of that
908
     * back by not needing the first 'k' squares and one multiply for the
909
     * first window.
910
     * Given the value of 4 for WEAVE_WORD_SIZE, this loop will only execute if
911
     * num_powers > 2, in which case powers will have been allocated.
912
     */
913
17.0k
    for (i = WEAVE_WORD_SIZE; i < num_powers; i++) {
914
16.5k
        int acc_index = i & (WEAVE_WORD_SIZE - 1); /* i % WEAVE_WORD_SIZE */
915
16.5k
        if (i & 1) {
916
8.25k
            MUL_NOWEAVE(montBase, &accum[acc_index - 1], &accum[acc_index]);
917
            /* we've filled the array do our 'per array' processing */
918
8.25k
            if (acc_index == (WEAVE_WORD_SIZE - 1)) {
919
4.12k
                MP_CHECKOK(mpi_to_weave(accum, powers + i - (WEAVE_WORD_SIZE - 1),
920
4.12k
                                        nLen, num_powers));
921
922
4.12k
                if (first_window <= i) {
923
327
                    MP_CHECKOK(mp_copy(&accum[first_window & (WEAVE_WORD_SIZE - 1)],
924
327
                                       &accum1));
925
327
                    first_window = num_powers;
926
327
                }
927
4.12k
            }
928
8.25k
        } else {
929
            /* up to 8 we can find 2^i-1 in the accum array, but at 8 we our source
930
             * and target are the same so we need to copy.. After that, the
931
             * value is overwritten, so we need to fetch it from the stored
932
             * weave array */
933
8.25k
            if (i > 2 * WEAVE_WORD_SIZE) {
934
6.66k
                MP_CHECKOK(weave_to_mpi(&accum2, powers, i / 2, nLen, num_powers));
935
13.3k
                SQR(&accum2, &accum[acc_index]);
936
13.3k
            } else {
937
1.59k
                int half_power_index = (i / 2) & (WEAVE_WORD_SIZE - 1);
938
1.59k
                if (half_power_index == acc_index) {
939
                    /* copy is cheaper than weave_to_mpi */
940
531
                    MP_CHECKOK(mp_copy(&accum[half_power_index], &accum2));
941
1.06k
                    SQR(&accum2, &accum[acc_index]);
942
1.06k
                } else {
943
1.06k
                    SQR(&accum[half_power_index], &accum[acc_index]);
944
1.06k
                }
945
1.59k
            }
946
8.25k
        }
947
16.5k
    }
948
/* if the accum1 isn't set, Then there is something wrong with our logic
949
 * above and is an internal programming error.
950
 */
951
580
#if MP_ARGCHK == 2
952
580
    assert(MP_USED(&accum1) != 0);
953
0
#endif
954
955
    /* set accumulator to montgomery residue of 1 */
956
0
    pa1 = &accum1;
957
580
    pa2 = &accum2;
958
959
    /* tmp is not used if window_bits == 1. */
960
580
    if (window_bits != 1) {
961
531
        MP_CHECKOK(mp_init_size(&tmp, 3 * nLen + 2));
962
531
    }
963
964
130k
    for (expOff = bits_in_exponent - window_bits * 2; expOff >= 0; expOff -= window_bits) {
965
129k
        mp_size smallExp;
966
129k
        MP_CHECKOK(mpl_get_bits(exponent, expOff, window_bits));
967
129k
        smallExp = (mp_size)res;
968
969
        /* handle unroll the loops */
970
129k
        switch (window_bits) {
971
559
            case 1:
972
559
                if (!smallExp) {
973
341
                    SQR(pa1, pa2);
974
341
                    SWAPPA;
975
341
                } else if (smallExp & 1) {
976
218
                    SQR(pa1, pa2);
977
218
                    MUL_NOWEAVE(montBase, pa2, pa1);
978
218
                } else {
979
0
                    abort();
980
0
                }
981
559
                break;
982
106k
            case 6:
983
106k
                SQR(pa1, pa2);
984
212k
                SQR(pa2, pa1);
985
            /* fall through */
986
116k
            case 4:
987
116k
                SQR(pa1, pa2);
988
232k
                SQR(pa2, pa1);
989
232k
                SQR(pa1, pa2);
990
232k
                SQR(pa2, pa1);
991
232k
                MUL(smallExp, pa1, pa2);
992
116k
                SWAPPA;
993
116k
                break;
994
13.1k
            case 5:
995
13.1k
                SQR(pa1, pa2);
996
26.2k
                SQR(pa2, pa1);
997
26.2k
                SQR(pa1, pa2);
998
26.2k
                SQR(pa2, pa1);
999
26.2k
                SQR(pa1, pa2);
1000
26.2k
                MUL(smallExp, pa2, pa1);
1001
13.1k
                break;
1002
13.1k
            default:
1003
0
                abort(); /* could do a loop? */
1004
129k
        }
1005
129k
    }
1006
1007
580
    res = s_mp_redc(pa1, mmm);
1008
580
    mp_exch(pa1, result);
1009
1010
580
CLEANUP:
1011
580
    mp_clear(&accum1);
1012
580
    mp_clear(&accum2);
1013
580
    mp_clear(&accum[0]);
1014
580
    mp_clear(&accum[1]);
1015
580
    mp_clear(&accum[2]);
1016
580
    mp_clear(&accum[3]);
1017
580
    mp_clear(&tmp);
1018
    /* zero required by FIPS here, can't use PORT_ZFree
1019
     * because mpi doesn't link with util */
1020
580
    if (powers) {
1021
531
        PORT_Memset(powers, 0, num_powers * sizeof(mp_digit));
1022
531
    }
1023
580
    free(powersArray);
1024
580
    return res;
1025
580
}
1026
#undef SQR
1027
#undef MUL
1028
#endif
1029
1030
mp_err
1031
mp_exptmod(const mp_int *inBase, const mp_int *exponent,
1032
           const mp_int *modulus, mp_int *result)
1033
1.37k
{
1034
1.37k
    const mp_int *base;
1035
1.37k
    mp_size bits_in_exponent, i, window_bits, odd_ints;
1036
1.37k
    mp_err res;
1037
1.37k
    int nLen;
1038
1.37k
    mp_int montBase, goodBase;
1039
1.37k
    mp_mont_modulus mmm;
1040
1.37k
#ifdef MP_USING_CACHE_SAFE_MOD_EXP
1041
1.37k
    static unsigned int max_window_bits;
1042
1.37k
#endif
1043
1044
    /* function for computing n0prime only works if n0 is odd */
1045
1.37k
    if (!mp_isodd(modulus))
1046
792
        return s_mp_exptmod(inBase, exponent, modulus, result);
1047
1048
580
    if (mp_cmp_z(inBase) == MP_LT)
1049
0
        return MP_RANGE;
1050
580
    MP_DIGITS(&montBase) = 0;
1051
580
    MP_DIGITS(&goodBase) = 0;
1052
1053
580
    if (mp_cmp(inBase, modulus) < 0) {
1054
494
        base = inBase;
1055
494
    } else {
1056
86
        MP_CHECKOK(mp_init(&goodBase));
1057
86
        base = &goodBase;
1058
86
        MP_CHECKOK(mp_mod(inBase, modulus, &goodBase));
1059
86
    }
1060
1061
580
    nLen = MP_USED(modulus);
1062
580
    MP_CHECKOK(mp_init_size(&montBase, 2 * nLen + 2));
1063
1064
580
    mmm.N = *modulus; /* a copy of the mp_int struct */
1065
1066
    /* compute n0', given n0, n0' = -(n0 ** -1) mod MP_RADIX
1067
    **        where n0 = least significant mp_digit of N, the modulus.
1068
    */
1069
580
    mmm.n0prime = mp_calculate_mont_n0i(modulus);
1070
1071
580
    MP_CHECKOK(mp_to_mont(base, modulus, &montBase));
1072
1073
580
    bits_in_exponent = mpl_significant_bits(exponent);
1074
580
#ifdef MP_USING_CACHE_SAFE_MOD_EXP
1075
580
    if (mp_using_cache_safe_exp) {
1076
580
        if (bits_in_exponent > 780)
1077
172
            window_bits = 6;
1078
408
        else if (bits_in_exponent > 256)
1079
118
            window_bits = 5;
1080
290
        else if (bits_in_exponent > 20)
1081
241
            window_bits = 4;
1082
        /* RSA public key exponents are typically under 20 bits (common values
1083
         * are: 3, 17, 65537) and a 4-bit window is inefficient
1084
         */
1085
49
        else
1086
49
            window_bits = 1;
1087
580
    } else
1088
0
#endif
1089
0
        if (bits_in_exponent > 480)
1090
0
        window_bits = 6;
1091
0
    else if (bits_in_exponent > 160)
1092
0
        window_bits = 5;
1093
0
    else if (bits_in_exponent > 20)
1094
0
        window_bits = 4;
1095
    /* RSA public key exponents are typically under 20 bits (common values
1096
     * are: 3, 17, 65537) and a 4-bit window is inefficient
1097
     */
1098
0
    else
1099
0
        window_bits = 1;
1100
1101
580
#ifdef MP_USING_CACHE_SAFE_MOD_EXP
1102
    /*
1103
     * clamp the window size based on
1104
     * the cache line size.
1105
     */
1106
580
    if (!max_window_bits) {
1107
2
        unsigned long cache_size = s_mpi_getProcessorLineSize();
1108
        /* processor has no cache, use 'fast' code always */
1109
2
        if (cache_size == 0) {
1110
0
            mp_using_cache_safe_exp = 0;
1111
0
        }
1112
2
        if ((cache_size == 0) || (cache_size >= 64)) {
1113
2
            max_window_bits = 6;
1114
2
        } else if (cache_size >= 32) {
1115
0
            max_window_bits = 5;
1116
0
        } else if (cache_size >= 16) {
1117
0
            max_window_bits = 4;
1118
0
        } else
1119
0
            max_window_bits = 1; /* should this be an assert? */
1120
2
    }
1121
1122
    /* clamp the window size down before we caclulate bits_in_exponent */
1123
580
    if (mp_using_cache_safe_exp) {
1124
580
        if (window_bits > max_window_bits) {
1125
0
            window_bits = max_window_bits;
1126
0
        }
1127
580
    }
1128
580
#endif
1129
1130
580
    odd_ints = 1 << (window_bits - 1);
1131
580
    i = bits_in_exponent % window_bits;
1132
580
    if (i != 0) {
1133
461
        bits_in_exponent += window_bits - i;
1134
461
    }
1135
1136
#ifdef MP_USING_MONT_MULF
1137
    if (mp_using_mont_mulf) {
1138
        MP_CHECKOK(s_mp_pad(&montBase, nLen));
1139
        res = mp_exptmod_f(&montBase, exponent, modulus, result, &mmm, nLen,
1140
                           bits_in_exponent, window_bits, odd_ints);
1141
    } else
1142
#endif
1143
580
#ifdef MP_USING_CACHE_SAFE_MOD_EXP
1144
580
        if (mp_using_cache_safe_exp) {
1145
580
        res = mp_exptmod_safe_i(&montBase, exponent, modulus, result, &mmm, nLen,
1146
580
                                bits_in_exponent, window_bits, 1 << window_bits);
1147
580
    } else
1148
0
#endif
1149
0
        res = mp_exptmod_i(&montBase, exponent, modulus, result, &mmm, nLen,
1150
0
                           bits_in_exponent, window_bits, odd_ints);
1151
1152
580
CLEANUP:
1153
580
    mp_clear(&montBase);
1154
580
    mp_clear(&goodBase);
1155
    /* Don't mp_clear mmm.N because it is merely a copy of modulus.
1156
    ** Just zap it.
1157
    */
1158
580
    memset(&mmm, 0, sizeof mmm);
1159
580
    return res;
1160
580
}