summaryrefslogtreecommitdiffstats
path: root/security/nss/lib/freebl/gcm.c
blob: e93970b8886a895291ada787951ff5118d867870 (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
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
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Thanks to Thomas Pornin for the ideas how to implement the constat time
 * binary multiplication. */

#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif
#include "blapii.h"
#include "blapit.h"
#include "gcm.h"
#include "ctr.h"
#include "secerr.h"
#include "prtypes.h"
#include "pkcs11t.h"

#include <limits.h>

/* Forward declarations */
SECStatus gcm_HashInit_hw(gcmHashContext *ghash);
SECStatus gcm_HashWrite_hw(gcmHashContext *ghash, unsigned char *outbuf);
SECStatus gcm_HashMult_hw(gcmHashContext *ghash, const unsigned char *buf,
                          unsigned int count);
SECStatus gcm_HashZeroX_hw(gcmHashContext *ghash);
SECStatus gcm_HashMult_sftw(gcmHashContext *ghash, const unsigned char *buf,
                            unsigned int count);
SECStatus gcm_HashMult_sftw32(gcmHashContext *ghash, const unsigned char *buf,
                              unsigned int count);

/* Stub definitions for the above *_hw functions, which shouldn't be
 * used unless NSS_X86_OR_X64 is defined */
#ifndef NSS_X86_OR_X64
SECStatus
gcm_HashWrite_hw(gcmHashContext *ghash, unsigned char *outbuf)
{
    PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
    return SECFailure;
}

SECStatus
gcm_HashMult_hw(gcmHashContext *ghash, const unsigned char *buf,
                unsigned int count)
{
    PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
    return SECFailure;
}

SECStatus
gcm_HashInit_hw(gcmHashContext *ghash)
{
    PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
    return SECFailure;
}

SECStatus
gcm_HashZeroX_hw(gcmHashContext *ghash)
{
    PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
    return SECFailure;
}
#endif /* NSS_X86_OR_X64 */

uint64_t
get64(const unsigned char *bytes)
{
    return ((uint64_t)bytes[0]) << 56 |
           ((uint64_t)bytes[1]) << 48 |
           ((uint64_t)bytes[2]) << 40 |
           ((uint64_t)bytes[3]) << 32 |
           ((uint64_t)bytes[4]) << 24 |
           ((uint64_t)bytes[5]) << 16 |
           ((uint64_t)bytes[6]) << 8 |
           ((uint64_t)bytes[7]);
}

/* Initialize a gcmHashContext */
SECStatus
gcmHash_InitContext(gcmHashContext *ghash, const unsigned char *H, PRBool sw)
{
    SECStatus rv = SECSuccess;

    ghash->cLen = 0;
    ghash->bufLen = 0;
    PORT_Memset(ghash->counterBuf, 0, sizeof(ghash->counterBuf));

    ghash->h_low = get64(H + 8);
    ghash->h_high = get64(H);
    if (clmul_support() && !sw) {
        rv = gcm_HashInit_hw(ghash);
    } else {
/* We fall back to the software implementation if we can't use / don't
         * want to use pclmul. */
#ifdef HAVE_INT128_SUPPORT
        ghash->ghash_mul = gcm_HashMult_sftw;
#else
        ghash->ghash_mul = gcm_HashMult_sftw32;
#endif
        ghash->x_high = ghash->x_low = 0;
        ghash->hw = PR_FALSE;
    }
    return rv;
}

#ifdef HAVE_INT128_SUPPORT
/* Binary multiplication x * y = r_high << 64 | r_low. */
void
bmul(uint64_t x, uint64_t y, uint64_t *r_high, uint64_t *r_low)
{
    uint128_t x1, x2, x3, x4, x5;
    uint128_t y1, y2, y3, y4, y5;
    uint128_t r, z;

    uint128_t m1 = (uint128_t)0x2108421084210842 << 64 | 0x1084210842108421;
    uint128_t m2 = (uint128_t)0x4210842108421084 << 64 | 0x2108421084210842;
    uint128_t m3 = (uint128_t)0x8421084210842108 << 64 | 0x4210842108421084;
    uint128_t m4 = (uint128_t)0x0842108421084210 << 64 | 0x8421084210842108;
    uint128_t m5 = (uint128_t)0x1084210842108421 << 64 | 0x0842108421084210;

    x1 = x & m1;
    y1 = y & m1;
    x2 = x & m2;
    y2 = y & m2;
    x3 = x & m3;
    y3 = y & m3;
    x4 = x & m4;
    y4 = y & m4;
    x5 = x & m5;
    y5 = y & m5;

    z = (x1 * y1) ^ (x2 * y5) ^ (x3 * y4) ^ (x4 * y3) ^ (x5 * y2);
    r = z & m1;
    z = (x1 * y2) ^ (x2 * y1) ^ (x3 * y5) ^ (x4 * y4) ^ (x5 * y3);
    r |= z & m2;
    z = (x1 * y3) ^ (x2 * y2) ^ (x3 * y1) ^ (x4 * y5) ^ (x5 * y4);
    r |= z & m3;
    z = (x1 * y4) ^ (x2 * y3) ^ (x3 * y2) ^ (x4 * y1) ^ (x5 * y5);
    r |= z & m4;
    z = (x1 * y5) ^ (x2 * y4) ^ (x3 * y3) ^ (x4 * y2) ^ (x5 * y1);
    r |= z & m5;

    *r_high = (uint64_t)(r >> 64);
    *r_low = (uint64_t)r;
}

SECStatus
gcm_HashMult_sftw(gcmHashContext *ghash, const unsigned char *buf,
                  unsigned int count)
{
    uint64_t ci_low, ci_high;
    size_t i;
    uint64_t z2_low, z2_high, z0_low, z0_high, z1a_low, z1a_high;
    uint128_t z_high = 0, z_low = 0;

    ci_low = ghash->x_low;
    ci_high = ghash->x_high;
    for (i = 0; i < count; i++, buf += 16) {
        ci_low ^= get64(buf + 8);
        ci_high ^= get64(buf);

        /* Do binary mult ghash->X = C * ghash->H (Karatsuba). */
        bmul(ci_high, ghash->h_high, &z2_high, &z2_low);
        bmul(ci_low, ghash->h_low, &z0_high, &z0_low);
        bmul(ci_high ^ ci_low, ghash->h_high ^ ghash->h_low, &z1a_high, &z1a_low);
        z1a_high ^= z2_high ^ z0_high;
        z1a_low ^= z2_low ^ z0_low;
        z_high = ((uint128_t)z2_high << 64) | (z2_low ^ z1a_high);
        z_low = (((uint128_t)z0_high << 64) | z0_low) ^ (((uint128_t)z1a_low) << 64);

        /* Shift one (multiply by x) as gcm spec is stupid. */
        z_high = (z_high << 1) | (z_low >> 127);
        z_low <<= 1;

        /* Reduce */
        z_low ^= (z_low << 127) ^ (z_low << 126) ^ (z_low << 121);
        z_high ^= z_low ^ (z_low >> 1) ^ (z_low >> 2) ^ (z_low >> 7);
        ci_low = (uint64_t)z_high;
        ci_high = (uint64_t)(z_high >> 64);
    }
    ghash->x_low = ci_low;
    ghash->x_high = ci_high;
    return SECSuccess;
}
#else
/* Binary multiplication x * y = r_high << 32 | r_low. */
void
bmul32(uint32_t x, uint32_t y, uint32_t *r_high, uint32_t *r_low)
{
    uint32_t x0, x1, x2, x3;
    uint32_t y0, y1, y2, y3;
    uint32_t m1 = (uint32_t)0x11111111;
    uint32_t m2 = (uint32_t)0x22222222;
    uint32_t m4 = (uint32_t)0x44444444;
    uint32_t m8 = (uint32_t)0x88888888;
    uint64_t z0, z1, z2, z3;
    uint64_t z;

    x0 = x & m1;
    x1 = x & m2;
    x2 = x & m4;
    x3 = x & m8;
    y0 = y & m1;
    y1 = y & m2;
    y2 = y & m4;
    y3 = y & m8;
    z0 = ((uint64_t)x0 * y0) ^ ((uint64_t)x1 * y3) ^
         ((uint64_t)x2 * y2) ^ ((uint64_t)x3 * y1);
    z1 = ((uint64_t)x0 * y1) ^ ((uint64_t)x1 * y0) ^
         ((uint64_t)x2 * y3) ^ ((uint64_t)x3 * y2);
    z2 = ((uint64_t)x0 * y2) ^ ((uint64_t)x1 * y1) ^
         ((uint64_t)x2 * y0) ^ ((uint64_t)x3 * y3);
    z3 = ((uint64_t)x0 * y3) ^ ((uint64_t)x1 * y2) ^
         ((uint64_t)x2 * y1) ^ ((uint64_t)x3 * y0);
    z0 &= ((uint64_t)m1 << 32) | m1;
    z1 &= ((uint64_t)m2 << 32) | m2;
    z2 &= ((uint64_t)m4 << 32) | m4;
    z3 &= ((uint64_t)m8 << 32) | m8;
    z = z0 | z1 | z2 | z3;
    *r_high = (uint32_t)(z >> 32);
    *r_low = (uint32_t)z;
}

SECStatus
gcm_HashMult_sftw32(gcmHashContext *ghash, const unsigned char *buf,
                    unsigned int count)
{
    size_t i;
    uint64_t ci_low, ci_high;
    uint64_t z_high_h, z_high_l, z_low_h, z_low_l;
    uint32_t ci_high_h, ci_high_l, ci_low_h, ci_low_l;
    uint32_t b_a_h, b_a_l, a_a_h, a_a_l, b_b_h, b_b_l;
    uint32_t a_b_h, a_b_l, b_c_h, b_c_l, a_c_h, a_c_l, c_c_h, c_c_l;
    uint32_t ci_highXlow_h, ci_highXlow_l, c_a_h, c_a_l, c_b_h, c_b_l;

    uint32_t h_high_h = (uint32_t)(ghash->h_high >> 32);
    uint32_t h_high_l = (uint32_t)ghash->h_high;
    uint32_t h_low_h = (uint32_t)(ghash->h_low >> 32);
    uint32_t h_low_l = (uint32_t)ghash->h_low;
    uint32_t h_highXlow_h = h_high_h ^ h_low_h;
    uint32_t h_highXlow_l = h_high_l ^ h_low_l;
    uint32_t h_highX_xored = h_highXlow_h ^ h_highXlow_l;

    for (i = 0; i < count; i++, buf += 16) {
        ci_low = ghash->x_low ^ get64(buf + 8);
        ci_high = ghash->x_high ^ get64(buf);
        ci_low_h = (uint32_t)(ci_low >> 32);
        ci_low_l = (uint32_t)ci_low;
        ci_high_h = (uint32_t)(ci_high >> 32);
        ci_high_l = (uint32_t)ci_high;
        ci_highXlow_h = ci_high_h ^ ci_low_h;
        ci_highXlow_l = ci_high_l ^ ci_low_l;

        /* Do binary mult ghash->X = C * ghash->H (recursive Karatsuba). */
        bmul32(ci_high_h, h_high_h, &a_a_h, &a_a_l);
        bmul32(ci_high_l, h_high_l, &a_b_h, &a_b_l);
        bmul32(ci_high_h ^ ci_high_l, h_high_h ^ h_high_l, &a_c_h, &a_c_l);
        a_c_h ^= a_a_h ^ a_b_h;
        a_c_l ^= a_a_l ^ a_b_l;
        a_a_l ^= a_c_h;
        a_b_h ^= a_c_l;
        /* ci_high * h_high = a_a_h:a_a_l:a_b_h:a_b_l */

        bmul32(ci_low_h, h_low_h, &b_a_h, &b_a_l);
        bmul32(ci_low_l, h_low_l, &b_b_h, &b_b_l);
        bmul32(ci_low_h ^ ci_low_l, h_low_h ^ h_low_l, &b_c_h, &b_c_l);
        b_c_h ^= b_a_h ^ b_b_h;
        b_c_l ^= b_a_l ^ b_b_l;
        b_a_l ^= b_c_h;
        b_b_h ^= b_c_l;
        /* ci_low * h_low = b_a_h:b_a_l:b_b_h:b_b_l */

        bmul32(ci_highXlow_h, h_highXlow_h, &c_a_h, &c_a_l);
        bmul32(ci_highXlow_l, h_highXlow_l, &c_b_h, &c_b_l);
        bmul32(ci_highXlow_h ^ ci_highXlow_l, h_highX_xored, &c_c_h, &c_c_l);
        c_c_h ^= c_a_h ^ c_b_h;
        c_c_l ^= c_a_l ^ c_b_l;
        c_a_l ^= c_c_h;
        c_b_h ^= c_c_l;
        /* (ci_high ^ ci_low) * (h_high ^ h_low) = c_a_h:c_a_l:c_b_h:c_b_l */

        c_a_h ^= b_a_h ^ a_a_h;
        c_a_l ^= b_a_l ^ a_a_l;
        c_b_h ^= b_b_h ^ a_b_h;
        c_b_l ^= b_b_l ^ a_b_l;
        z_high_h = ((uint64_t)a_a_h << 32) | a_a_l;
        z_high_l = (((uint64_t)a_b_h << 32) | a_b_l) ^
                   (((uint64_t)c_a_h << 32) | c_a_l);
        z_low_h = (((uint64_t)b_a_h << 32) | b_a_l) ^
                  (((uint64_t)c_b_h << 32) | c_b_l);
        z_low_l = ((uint64_t)b_b_h << 32) | b_b_l;

        /* Shift one (multiply by x) as gcm spec is stupid. */
        z_high_h = z_high_h << 1 | z_high_l >> 63;
        z_high_l = z_high_l << 1 | z_low_h >> 63;
        z_low_h = z_low_h << 1 | z_low_l >> 63;
        z_low_l <<= 1;

        /* Reduce */
        z_low_h ^= (z_low_l << 63) ^ (z_low_l << 62) ^ (z_low_l << 57);
        z_high_h ^= z_low_h ^ (z_low_h >> 1) ^ (z_low_h >> 2) ^ (z_low_h >> 7);
        z_high_l ^= z_low_l ^ (z_low_l >> 1) ^ (z_low_l >> 2) ^ (z_low_l >> 7) ^
                    (z_low_h << 63) ^ (z_low_h << 62) ^ (z_low_h << 57);
        ghash->x_high = z_high_h;
        ghash->x_low = z_high_l;
    }
    return SECSuccess;
}
#endif /* HAVE_INT128_SUPPORT */

static SECStatus
gcm_zeroX(gcmHashContext *ghash)
{
    SECStatus rv = SECSuccess;

    if (ghash->hw) {
        rv = gcm_HashZeroX_hw(ghash);
    }

    ghash->x_high = ghash->x_low = 0;
    return rv;
}

/*
 * implement GCM GHASH using the freebl GHASH function. The gcm_HashMult
 * function always takes AES_BLOCK_SIZE lengths of data. gcmHash_Update will
 * format the data properly.
 */
SECStatus
gcmHash_Update(gcmHashContext *ghash, const unsigned char *buf,
               unsigned int len)
{
    unsigned int blocks;
    SECStatus rv;

    ghash->cLen += (len * PR_BITS_PER_BYTE);

    /* first deal with the current buffer of data. Try to fill it out so
     * we can hash it */
    if (ghash->bufLen) {
        unsigned int needed = PR_MIN(len, AES_BLOCK_SIZE - ghash->bufLen);
        if (needed != 0) {
            PORT_Memcpy(ghash->buffer + ghash->bufLen, buf, needed);
        }
        buf += needed;
        len -= needed;
        ghash->bufLen += needed;
        if (len == 0) {
            /* didn't add enough to hash the data, nothing more do do */
            return SECSuccess;
        }
        PORT_Assert(ghash->bufLen == AES_BLOCK_SIZE);
        /* hash the buffer and clear it */
        rv = ghash->ghash_mul(ghash, ghash->buffer, 1);
        PORT_Memset(ghash->buffer, 0, AES_BLOCK_SIZE);
        ghash->bufLen = 0;
        if (rv != SECSuccess) {
            return SECFailure;
        }
    }
    /* now hash any full blocks remaining in the data stream */
    blocks = len / AES_BLOCK_SIZE;
    if (blocks) {
        rv = ghash->ghash_mul(ghash, buf, blocks);
        if (rv != SECSuccess) {
            return SECFailure;
        }
        buf += blocks * AES_BLOCK_SIZE;
        len -= blocks * AES_BLOCK_SIZE;
    }

    /* save any remainder in the buffer to be hashed with the next call */
    if (len != 0) {
        PORT_Memcpy(ghash->buffer, buf, len);
        ghash->bufLen = len;
    }
    return SECSuccess;
}

/*
 * write out any partial blocks zero padded through the GHASH engine,
 * save the lengths for the final completion of the hash
 */
static SECStatus
gcmHash_Sync(gcmHashContext *ghash)
{
    int i;
    SECStatus rv;

    /* copy the previous counter to the upper block */
    PORT_Memcpy(ghash->counterBuf, &ghash->counterBuf[GCM_HASH_LEN_LEN],
                GCM_HASH_LEN_LEN);
    /* copy the current counter in the lower block */
    for (i = 0; i < GCM_HASH_LEN_LEN; i++) {
        ghash->counterBuf[GCM_HASH_LEN_LEN + i] =
            (ghash->cLen >> ((GCM_HASH_LEN_LEN - 1 - i) * PR_BITS_PER_BYTE)) & 0xff;
    }
    ghash->cLen = 0;

    /* now zero fill the buffer and hash the last block */
    if (ghash->bufLen) {
        PORT_Memset(ghash->buffer + ghash->bufLen, 0, AES_BLOCK_SIZE - ghash->bufLen);
        rv = ghash->ghash_mul(ghash, ghash->buffer, 1);
        PORT_Memset(ghash->buffer, 0, AES_BLOCK_SIZE);
        ghash->bufLen = 0;
        if (rv != SECSuccess) {
            return SECFailure;
        }
    }
    return SECSuccess;
}

#define WRITE64(x, bytes)   \
    (bytes)[0] = (x) >> 56; \
    (bytes)[1] = (x) >> 48; \
    (bytes)[2] = (x) >> 40; \
    (bytes)[3] = (x) >> 32; \
    (bytes)[4] = (x) >> 24; \
    (bytes)[5] = (x) >> 16; \
    (bytes)[6] = (x) >> 8;  \
    (bytes)[7] = (x);

/*
 * This does the final sync, hashes the lengths, then returns
 * "T", the hashed output.
 */
SECStatus
gcmHash_Final(gcmHashContext *ghash, unsigned char *outbuf,
              unsigned int *outlen, unsigned int maxout)
{
    unsigned char T[MAX_BLOCK_SIZE];
    SECStatus rv;

    rv = gcmHash_Sync(ghash);
    if (rv != SECSuccess) {
        goto cleanup;
    }

    rv = ghash->ghash_mul(ghash, ghash->counterBuf,
                          (GCM_HASH_LEN_LEN * 2) / AES_BLOCK_SIZE);
    if (rv != SECSuccess) {
        goto cleanup;
    }

    if (ghash->hw) {
        rv = gcm_HashWrite_hw(ghash, T);
        if (rv != SECSuccess) {
            goto cleanup;
        }
    } else {
        WRITE64(ghash->x_low, T + 8);
        WRITE64(ghash->x_high, T);
    }

    if (maxout > AES_BLOCK_SIZE) {
        maxout = AES_BLOCK_SIZE;
    }
    PORT_Memcpy(outbuf, T, maxout);
    *outlen = maxout;
    rv = SECSuccess;

cleanup:
    PORT_Memset(T, 0, sizeof(T));
    return rv;
}

SECStatus
gcmHash_Reset(gcmHashContext *ghash, const unsigned char *AAD,
              unsigned int AADLen)
{
    SECStatus rv;

    // Limit AADLen in accordance with SP800-38D
    if (sizeof(AADLen) >= 8 && AADLen > (1ULL << 61) - 1) {
        PORT_SetError(SEC_ERROR_INPUT_LEN);
        return SECFailure;
    }

    ghash->cLen = 0;
    PORT_Memset(ghash->counterBuf, 0, GCM_HASH_LEN_LEN * 2);
    ghash->bufLen = 0;
    rv = gcm_zeroX(ghash);
    if (rv != SECSuccess) {
        return rv;
    }

    /* now kick things off by hashing the Additional Authenticated Data */
    if (AADLen != 0) {
        rv = gcmHash_Update(ghash, AAD, AADLen);
        if (rv != SECSuccess) {
            return SECFailure;
        }
        rv = gcmHash_Sync(ghash);
        if (rv != SECSuccess) {
            return SECFailure;
        }
    }
    return SECSuccess;
}

/**************************************************************************
 *           Now implement the GCM using gcmHash and CTR                  *
 **************************************************************************/

/* state to handle the full GCM operation (hash and counter) */
struct GCMContextStr {
    gcmHashContext *ghash_context;
    CTRContext ctr_context;
    unsigned long tagBits;
    unsigned char tagKey[MAX_BLOCK_SIZE];
};

GCMContext *
GCM_CreateContext(void *context, freeblCipherFunc cipher,
                  const unsigned char *params)
{
    GCMContext *gcm = NULL;
    gcmHashContext *ghash = NULL;
    unsigned char H[MAX_BLOCK_SIZE];
    unsigned int tmp;
    PRBool freeCtr = PR_FALSE;
    const CK_GCM_PARAMS *gcmParams = (const CK_GCM_PARAMS *)params;
    CK_AES_CTR_PARAMS ctrParams;
    SECStatus rv;
#ifdef DISABLE_HW_GCM
    const PRBool sw = PR_TRUE;
#else
    const PRBool sw = PR_FALSE;
#endif

    if (gcmParams->ulIvLen == 0) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return NULL;
    }
    gcm = PORT_ZNew(GCMContext);
    if (gcm == NULL) {
        return NULL;
    }
    ghash = PORT_ZNewAligned(gcmHashContext, 16, mem);

    /* first plug in the ghash context */
    gcm->ghash_context = ghash;
    PORT_Memset(H, 0, AES_BLOCK_SIZE);
    rv = (*cipher)(context, H, &tmp, AES_BLOCK_SIZE, H, AES_BLOCK_SIZE, AES_BLOCK_SIZE);
    if (rv != SECSuccess) {
        goto loser;
    }
    rv = gcmHash_InitContext(ghash, H, sw);
    if (rv != SECSuccess) {
        goto loser;
    }

    /* fill in the Counter context */
    ctrParams.ulCounterBits = 32;
    PORT_Memset(ctrParams.cb, 0, sizeof(ctrParams.cb));
    if (gcmParams->ulIvLen == 12) {
        PORT_Memcpy(ctrParams.cb, gcmParams->pIv, gcmParams->ulIvLen);
        ctrParams.cb[AES_BLOCK_SIZE - 1] = 1;
    } else {
        rv = gcmHash_Update(ghash, gcmParams->pIv, gcmParams->ulIvLen);
        if (rv != SECSuccess) {
            goto loser;
        }
        rv = gcmHash_Final(ghash, ctrParams.cb, &tmp, AES_BLOCK_SIZE);
        if (rv != SECSuccess) {
            goto loser;
        }
    }
    rv = CTR_InitContext(&gcm->ctr_context, context, cipher,
                         (unsigned char *)&ctrParams);
    if (rv != SECSuccess) {
        goto loser;
    }
    freeCtr = PR_TRUE;

    /* fill in the gcm structure */
    gcm->tagBits = gcmParams->ulTagBits; /* save for final step */
    /* calculate the final tag key. NOTE: gcm->tagKey is zero to start with.
     * if this assumption changes, we would need to explicitly clear it here */
    rv = CTR_Update(&gcm->ctr_context, gcm->tagKey, &tmp, AES_BLOCK_SIZE,
                    gcm->tagKey, AES_BLOCK_SIZE, AES_BLOCK_SIZE);
    if (rv != SECSuccess) {
        goto loser;
    }

    /* finally mix in the AAD data */
    rv = gcmHash_Reset(ghash, gcmParams->pAAD, gcmParams->ulAADLen);
    if (rv != SECSuccess) {
        goto loser;
    }

    return gcm;

loser:
    if (freeCtr) {
        CTR_DestroyContext(&gcm->ctr_context, PR_FALSE);
    }
    if (ghash && ghash->mem) {
        PORT_Free(ghash->mem);
    }
    if (gcm) {
        PORT_Free(gcm);
    }
    return NULL;
}

void
GCM_DestroyContext(GCMContext *gcm, PRBool freeit)
{
    /* these two are statically allocated and will be freed when we free
     * gcm. call their destroy functions to free up any locally
     * allocated data (like mp_int's) */
    CTR_DestroyContext(&gcm->ctr_context, PR_FALSE);
    PORT_Free(gcm->ghash_context->mem);
    PORT_Memset(&gcm->tagBits, 0, sizeof(gcm->tagBits));
    PORT_Memset(gcm->tagKey, 0, sizeof(gcm->tagKey));
    if (freeit) {
        PORT_Free(gcm);
    }
}

static SECStatus
gcm_GetTag(GCMContext *gcm, unsigned char *outbuf,
           unsigned int *outlen, unsigned int maxout)
{
    unsigned int tagBytes;
    unsigned int extra;
    unsigned int i;
    SECStatus rv;

    tagBytes = (gcm->tagBits + (PR_BITS_PER_BYTE - 1)) / PR_BITS_PER_BYTE;
    extra = tagBytes * PR_BITS_PER_BYTE - gcm->tagBits;

    if (outbuf == NULL) {
        *outlen = tagBytes;
        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
        return SECFailure;
    }

    if (maxout < tagBytes) {
        *outlen = tagBytes;
        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
        return SECFailure;
    }
    maxout = tagBytes;
    rv = gcmHash_Final(gcm->ghash_context, outbuf, outlen, maxout);
    if (rv != SECSuccess) {
        return SECFailure;
    }

    for (i = 0; i < *outlen; i++) {
        outbuf[i] ^= gcm->tagKey[i];
    }
    /* mask off any extra bits we got */
    if (extra) {
        outbuf[tagBytes - 1] &= ~((1 << extra) - 1);
    }
    return SECSuccess;
}

/*
 * See The Galois/Counter Mode of Operation, McGrew and Viega.
 *  GCM is basically counter mode with a specific initialization and
 *  built in macing operation.
 */
SECStatus
GCM_EncryptUpdate(GCMContext *gcm, unsigned char *outbuf,
                  unsigned int *outlen, unsigned int maxout,
                  const unsigned char *inbuf, unsigned int inlen,
                  unsigned int blocksize)
{
    SECStatus rv;
    unsigned int tagBytes;
    unsigned int len;

    PORT_Assert(blocksize == AES_BLOCK_SIZE);
    if (blocksize != AES_BLOCK_SIZE) {
        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
        return SECFailure;
    }

    tagBytes = (gcm->tagBits + (PR_BITS_PER_BYTE - 1)) / PR_BITS_PER_BYTE;
    if (UINT_MAX - inlen < tagBytes) {
        PORT_SetError(SEC_ERROR_INPUT_LEN);
        return SECFailure;
    }
    if (maxout < inlen + tagBytes) {
        *outlen = inlen + tagBytes;
        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
        return SECFailure;
    }

    rv = CTR_Update(&gcm->ctr_context, outbuf, outlen, maxout,
                    inbuf, inlen, AES_BLOCK_SIZE);
    if (rv != SECSuccess) {
        return SECFailure;
    }
    rv = gcmHash_Update(gcm->ghash_context, outbuf, *outlen);
    if (rv != SECSuccess) {
        PORT_Memset(outbuf, 0, *outlen); /* clear the output buffer */
        *outlen = 0;
        return SECFailure;
    }
    rv = gcm_GetTag(gcm, outbuf + *outlen, &len, maxout - *outlen);
    if (rv != SECSuccess) {
        PORT_Memset(outbuf, 0, *outlen); /* clear the output buffer */
        *outlen = 0;
        return SECFailure;
    };
    *outlen += len;
    return SECSuccess;
}

/*
 * See The Galois/Counter Mode of Operation, McGrew and Viega.
 *  GCM is basically counter mode with a specific initialization and
 *  built in macing operation. NOTE: the only difference between Encrypt
 *  and Decrypt is when we calculate the mac. That is because the mac must
 *  always be calculated on the cipher text, not the plain text, so for
 *  encrypt, we do the CTR update first and for decrypt we do the mac first.
 */
SECStatus
GCM_DecryptUpdate(GCMContext *gcm, unsigned char *outbuf,
                  unsigned int *outlen, unsigned int maxout,
                  const unsigned char *inbuf, unsigned int inlen,
                  unsigned int blocksize)
{
    SECStatus rv;
    unsigned int tagBytes;
    unsigned char tag[MAX_BLOCK_SIZE];
    const unsigned char *intag;
    unsigned int len;

    PORT_Assert(blocksize == AES_BLOCK_SIZE);
    if (blocksize != AES_BLOCK_SIZE) {
        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
        return SECFailure;
    }

    tagBytes = (gcm->tagBits + (PR_BITS_PER_BYTE - 1)) / PR_BITS_PER_BYTE;

    /* get the authentication block */
    if (inlen < tagBytes) {
        PORT_SetError(SEC_ERROR_INPUT_LEN);
        return SECFailure;
    }

    inlen -= tagBytes;
    intag = inbuf + inlen;

    /* verify the block */
    rv = gcmHash_Update(gcm->ghash_context, inbuf, inlen);
    if (rv != SECSuccess) {
        return SECFailure;
    }
    rv = gcm_GetTag(gcm, tag, &len, AES_BLOCK_SIZE);
    if (rv != SECSuccess) {
        return SECFailure;
    }
    /* Don't decrypt if we can't authenticate the encrypted data!
     * This assumes that if tagBits is not a multiple of 8, intag will
     * preserve the masked off missing bits.  */
    if (NSS_SecureMemcmp(tag, intag, tagBytes) != 0) {
        /* force a CKR_ENCRYPTED_DATA_INVALID error at in softoken */
        PORT_SetError(SEC_ERROR_BAD_DATA);
        PORT_Memset(tag, 0, sizeof(tag));
        return SECFailure;
    }
    PORT_Memset(tag, 0, sizeof(tag));
    /* finish the decryption */
    return CTR_Update(&gcm->ctr_context, outbuf, outlen, maxout,
                      inbuf, inlen, AES_BLOCK_SIZE);
}