-
Notifications
You must be signed in to change notification settings - Fork 8
/
pair_fruit.c
1062 lines (846 loc) · 27.5 KB
/
pair_fruit.c
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
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
*
* The Secure Remote Password 6a implementation is adapted from:
* - Tom Cocagne
* <https://github.com/cocagne/csrp>
*
* The MIT License (MIT)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is furnished to do
* so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <plist/plist.h>
#include <sodium.h>
#include <assert.h>
#include "pair-internal.h"
/* ----------------------------- DEFINES ETC ------------------------------- */
#define USERNAME "12:34:56:78:90:AB"
#define EPK_LENGTH 32
#define AUTHTAG_LENGTH 16
#define AES_SETUP_KEY "Pair-Setup-AES-Key"
#define AES_SETUP_IV "Pair-Setup-AES-IV"
#define AES_VERIFY_KEY "Pair-Verify-AES-Key"
#define AES_VERIFY_IV "Pair-Verify-AES-IV"
/* ---------------------------------- SRP ---------------------------------- */
typedef enum
{
SRP_NG_2048,
SRP_NG_CUSTOM
} SRP_NGType;
typedef struct
{
bnum N;
bnum g;
int N_len;
} NGConstant;
struct SRPUser
{
enum hash_alg alg;
NGConstant *ng;
bnum a;
bnum A;
bnum S;
const unsigned char *bytes_A;
int authenticated;
char *username;
unsigned char *password;
int password_len;
unsigned char M [SHA512_DIGEST_LENGTH];
unsigned char H_AMK [SHA512_DIGEST_LENGTH];
unsigned char session_key [2 * SHA512_DIGEST_LENGTH]; // See hash_session_key()
int session_key_len;
};
struct NGHex
{
const char *n_hex;
const char *g_hex;
};
// We only need 2048 right now, but keep the array in case we want to add others later
// All constants here were pulled from Appendix A of RFC 5054
static struct NGHex global_Ng_constants[] =
{
{ /* 2048 */
"AC6BDB41324A9A9BF166DE5E1389582FAF72B6651987EE07FC3192943DB56050A37329CBB4"
"A099ED8193E0757767A13DD52312AB4B03310DCD7F48A9DA04FD50E8083969EDB767B0CF60"
"95179A163AB3661A05FBD5FAAAE82918A9962F0B93B855F97993EC975EEAA80D740ADBF4FF"
"747359D041D5C33EA71D281E446B14773BCA97B43A23FB801676BD207A436C6481F1D2B907"
"8717461A5B9D32E688F87748544523B524B0D57D5EA77A2775D2ECFA032CFBDBF52FB37861"
"60279004E57AE6AF874E7303CE53299CCC041C7BC308D82A5698F3A8D0C38271AE35F8E9DB"
"FBB694B5C803D89F7AE435DE236D525F54759B65E372FCD68EF20FA7111F9E4AFF73",
"2"
},
{0,0} /* null sentinel */
};
static NGConstant *
new_ng(SRP_NGType ng_type, const char *n_hex, const char *g_hex)
{
NGConstant *ng = calloc(1, sizeof(NGConstant));
if ( ng_type != SRP_NG_CUSTOM )
{
n_hex = global_Ng_constants[ ng_type ].n_hex;
g_hex = global_Ng_constants[ ng_type ].g_hex;
}
bnum_hex2bn(ng->N, n_hex);
bnum_hex2bn(ng->g, g_hex);
ng->N_len = bnum_num_bytes(ng->N);
return ng;
}
static void
free_ng(NGConstant * ng)
{
if (!ng)
return;
bnum_free(ng->N);
bnum_free(ng->g);
free(ng);
}
static bnum
calculate_x(enum hash_alg alg, const bnum salt, const char *username, const unsigned char *password, int password_len)
{
unsigned char ucp_hash[SHA512_DIGEST_LENGTH];
HashCTX ctx;
hash_init( alg, &ctx );
hash_update( alg, &ctx, username, strlen(username) );
hash_update( alg, &ctx, ":", 1 );
hash_update( alg, &ctx, password, password_len );
hash_final( alg, &ctx, ucp_hash );
return H_ns( alg, salt, ucp_hash, hash_length(alg) );
}
static int
hash_session_key(enum hash_alg alg, const bnum n, unsigned char *dest)
{
int nbytes = bnum_num_bytes(n);
unsigned char *bin = malloc(nbytes);
unsigned char fourbytes[4] = { 0 }; // Only God knows the reason for this, and perhaps some poor soul at Apple
bnum_bn2bin(n, bin, nbytes);
hash_ab(alg, dest, bin, nbytes, fourbytes, sizeof(fourbytes));
fourbytes[3] = 1; // Again, only ...
hash_ab(alg, dest + hash_length(alg), bin, nbytes, fourbytes, sizeof(fourbytes));
free(bin);
return (2 * hash_length(alg));
}
static void
calculate_M(enum hash_alg alg, NGConstant *ng, unsigned char *dest, const char *I, const bnum s,
const bnum A, const bnum B, const unsigned char *K, int K_len)
{
unsigned char H_N[ SHA512_DIGEST_LENGTH ];
unsigned char H_g[ SHA512_DIGEST_LENGTH ];
unsigned char H_I[ SHA512_DIGEST_LENGTH ];
unsigned char H_xor[ SHA512_DIGEST_LENGTH ];
HashCTX ctx;
int i = 0;
int hash_len = hash_length(alg);
hash_num( alg, ng->N, H_N );
hash_num( alg, ng->g, H_g );
hash(alg, (const unsigned char *)I, strlen(I), H_I);
for (i=0; i < hash_len; i++ )
H_xor[i] = H_N[i] ^ H_g[i];
hash_init( alg, &ctx );
hash_update( alg, &ctx, H_xor, hash_len );
hash_update( alg, &ctx, H_I, hash_len );
update_hash_n( alg, &ctx, s );
update_hash_n( alg, &ctx, A );
update_hash_n( alg, &ctx, B );
hash_update( alg, &ctx, K, K_len );
hash_final( alg, &ctx, dest );
}
static void
calculate_H_AMK(enum hash_alg alg, unsigned char *dest, const bnum A, const unsigned char * M, const unsigned char * K, int K_len)
{
HashCTX ctx;
hash_init( alg, &ctx );
update_hash_n( alg, &ctx, A );
hash_update( alg, &ctx, M, hash_length(alg) );
hash_update( alg, &ctx, K, K_len );
hash_final( alg, &ctx, dest );
}
static struct SRPUser *
srp_user_new(enum hash_alg alg, SRP_NGType ng_type, const char *username,
const unsigned char *bytes_password, int len_password,
const char *n_hex, const char *g_hex)
{
struct SRPUser *usr = calloc(1, sizeof(struct SRPUser));
int ulen = strlen(username) + 1;
if (!usr)
goto err_exit;
usr->alg = alg;
usr->ng = new_ng( ng_type, n_hex, g_hex );
bnum_new(usr->a);
bnum_new(usr->A);
bnum_new(usr->S);
if (!usr->ng || !usr->a || !usr->A || !usr->S)
goto err_exit;
usr->username = malloc(ulen);
usr->password = malloc(len_password);
usr->password_len = len_password;
if (!usr->username || !usr->password)
goto err_exit;
memcpy(usr->username, username, ulen);
memcpy(usr->password, bytes_password, len_password);
usr->authenticated = 0;
usr->bytes_A = 0;
return usr;
err_exit:
if (!usr)
return NULL;
bnum_free(usr->a);
bnum_free(usr->A);
bnum_free(usr->S);
free(usr->username);
if (usr->password)
{
memset(usr->password, 0, usr->password_len);
free(usr->password);
}
free(usr);
return NULL;
}
static void
srp_user_free(struct SRPUser *usr)
{
if(!usr)
return;
bnum_free(usr->a);
bnum_free(usr->A);
bnum_free(usr->S);
free_ng(usr->ng);
memset(usr->password, 0, usr->password_len);
free(usr->username);
free(usr->password);
free((char *)usr->bytes_A);
memset(usr, 0, sizeof(*usr));
free(usr);
}
static int
srp_user_is_authenticated(struct SRPUser *usr)
{
return usr->authenticated;
}
static const unsigned char *
srp_user_get_session_key(struct SRPUser *usr, int *key_length)
{
if (key_length)
*key_length = usr->session_key_len;
return usr->session_key;
}
/* Output: username, bytes_A, len_A */
static void
srp_user_start_authentication(struct SRPUser *usr, const char **username,
const unsigned char **bytes_A, int *len_A)
{
bnum_random(usr->a, 256);
bnum_modexp(usr->A, usr->ng->g, usr->a, usr->ng->N);
*len_A = bnum_num_bytes(usr->A);
*bytes_A = malloc(*len_A);
if (!*bytes_A)
{
*len_A = 0;
*bytes_A = 0;
*username = 0;
return;
}
bnum_bn2bin(usr->A, (unsigned char *) *bytes_A, *len_A);
usr->bytes_A = *bytes_A;
*username = usr->username;
}
/* Output: bytes_M. Buffer length is SHA512_DIGEST_LENGTH */
static void
srp_user_process_challenge(struct SRPUser *usr, const unsigned char *bytes_s, int len_s,
const unsigned char *bytes_B, int len_B,
const unsigned char **bytes_M, int *len_M )
{
bnum s, B, k, v;
bnum tmp1, tmp2, tmp3;
bnum u, x;
*len_M = 0;
*bytes_M = NULL;
bnum_bin2bn(s, bytes_s, len_s);
bnum_bin2bn(B, bytes_B, len_B);
k = H_nn_pad(usr->alg, usr->ng->N, usr->ng->g, usr->ng->N_len);
bnum_new(v);
bnum_new(tmp1);
bnum_new(tmp2);
bnum_new(tmp3);
if (!s || !B || !k || !v || !tmp1 || !tmp2 || !tmp3)
goto cleanup1;
u = H_nn_pad(usr->alg, usr->A, B, usr->ng->N_len);
x = calculate_x(usr->alg, s, usr->username, usr->password, usr->password_len);
if (!u || !x)
goto cleanup2;
// SRP-6a safety check
if (!bnum_is_zero(B) && !bnum_is_zero(u))
{
bnum_modexp(v, usr->ng->g, x, usr->ng->N);
// S = (B - k*(g^x)) ^ (a + ux)
bnum_mul(tmp1, u, x);
bnum_add(tmp2, usr->a, tmp1); // tmp2 = (a + ux)
bnum_modexp(tmp1, usr->ng->g, x, usr->ng->N);
bnum_mul(tmp3, k, tmp1); // tmp3 = k*(g^x)
bnum_sub(tmp1, B, tmp3); // tmp1 = (B - K*(g^x))
bnum_modexp(usr->S, tmp1, tmp2, usr->ng->N);
usr->session_key_len = hash_session_key(usr->alg, usr->S, usr->session_key);
calculate_M(usr->alg, usr->ng, usr->M, usr->username, s, usr->A, B, usr->session_key, usr->session_key_len);
calculate_H_AMK(usr->alg, usr->H_AMK, usr->A, usr->M, usr->session_key, usr->session_key_len);
*bytes_M = usr->M;
*len_M = hash_length(usr->alg);
}
cleanup2:
bnum_free(x);
bnum_free(u);
cleanup1:
bnum_free(tmp3);
bnum_free(tmp2);
bnum_free(tmp1);
bnum_free(v);
bnum_free(k);
bnum_free(B);
bnum_free(s);
}
static void
srp_user_verify_session(struct SRPUser *usr, const unsigned char *bytes_HAMK)
{
if (memcmp(usr->H_AMK, bytes_HAMK, hash_length(usr->alg)) == 0)
usr->authenticated = 1;
}
/* -------------------------------- HELPERS -------------------------------- */
static int
encrypt_gcm(unsigned char *ciphertext, int ciphertext_len, unsigned char *tag, unsigned char *plaintext, int plaintext_len, unsigned char *key, unsigned char *iv, const char **errmsg)
{
#ifdef CONFIG_OPENSSL
EVP_CIPHER_CTX *ctx;
int len;
*errmsg = NULL;
if ( !(ctx = EVP_CIPHER_CTX_new()) ||
(EVP_EncryptInit_ex(ctx, EVP_aes_128_gcm(), NULL, NULL, NULL) != 1) ||
(EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, 16, NULL) != 1) ||
(EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv) != 1) )
{
*errmsg = "Error initialising AES 128 GCM encryption";
goto error;
}
if (EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len) != 1)
{
*errmsg = "Error GCM encrypting";
goto error;
}
if (len > ciphertext_len)
{
*errmsg = "Bug! Buffer overflow";
goto error;
}
if (EVP_EncryptFinal_ex(ctx, ciphertext + len, &len) != 1)
{
*errmsg = "Error finalising GCM encryption";
goto error;
}
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, AUTHTAG_LENGTH, tag) != 1)
{
*errmsg = "Error getting authtag";
goto error;
}
EVP_CIPHER_CTX_free(ctx);
return 0;
error:
EVP_CIPHER_CTX_free(ctx);
return -1;
#elif CONFIG_GCRYPT
gcry_cipher_hd_t hd;
gcry_error_t err;
err = gcry_cipher_open(&hd, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_GCM, 0);
if (err)
{
*errmsg = "Error initialising AES 128 GCM encryption";
return -1;
}
err = gcry_cipher_setkey(hd, key, gcry_cipher_get_algo_keylen(GCRY_CIPHER_AES128));
if (err)
{
*errmsg = "Could not set key for AES 128 GCM";
goto error;
}
err = gcry_cipher_setiv(hd, iv, gcry_cipher_get_algo_blklen(GCRY_CIPHER_AES128));
if (err)
{
*errmsg = "Could not set iv for AES 128 GCM";
goto error;
}
err = gcry_cipher_encrypt(hd, ciphertext, ciphertext_len, plaintext, plaintext_len);
if (err)
{
*errmsg = "Error GCM encrypting";
goto error;
}
err = gcry_cipher_gettag(hd, tag, AUTHTAG_LENGTH);
if (err)
{
*errmsg = "Error getting authtag";
goto error;
}
gcry_cipher_close(hd);
return 0;
error:
gcry_cipher_close(hd);
return -1;
#endif
}
static int
encrypt_ctr(unsigned char *ciphertext, int ciphertext_len,
unsigned char *plaintext1, int plaintext1_len, unsigned char *plaintext2, int plaintext2_len,
unsigned char *key, unsigned char *iv, const char **errmsg)
{
#ifdef CONFIG_OPENSSL
EVP_CIPHER_CTX *ctx;
int len;
*errmsg = NULL;
if ( !(ctx = EVP_CIPHER_CTX_new()) || (EVP_EncryptInit_ex(ctx, EVP_aes_128_ctr(), NULL, key, iv) != 1) )
{
*errmsg = "Error initialising AES 128 CTR encryption";
goto error;
}
if ( (EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext1, plaintext1_len) != 1) ||
(EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext2, plaintext2_len) != 1) )
{
*errmsg = "Error CTR encrypting";
goto error;
}
if (EVP_EncryptFinal_ex(ctx, ciphertext + len, &len) != 1)
{
*errmsg = "Error finalising encryption";
goto error;
}
EVP_CIPHER_CTX_free(ctx);
return 0;
error:
EVP_CIPHER_CTX_free(ctx);
return -1;
#elif CONFIG_GCRYPT
gcry_cipher_hd_t hd;
gcry_error_t err;
err = gcry_cipher_open(&hd, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CTR, 0);
if (err)
{
*errmsg = "Error initialising AES 128 CTR encryption";
return -1;
}
err = gcry_cipher_setkey(hd, key, gcry_cipher_get_algo_keylen(GCRY_CIPHER_AES128));
if (err)
{
*errmsg = "Could not set key for AES 128 CTR";
goto error;
}
err = gcry_cipher_setctr(hd, iv, gcry_cipher_get_algo_blklen(GCRY_CIPHER_AES128));
if (err)
{
*errmsg = "Could not set iv for AES 128 CTR";
goto error;
}
err = gcry_cipher_encrypt(hd, ciphertext, ciphertext_len, plaintext1, plaintext1_len);
if (err)
{
*errmsg = "Error CTR encrypting plaintext 1";
goto error;
}
err = gcry_cipher_encrypt(hd, ciphertext, ciphertext_len, plaintext2, plaintext2_len);
if (err)
{
*errmsg = "Error CTR encrypting plaintext 2";
goto error;
}
gcry_cipher_close(hd);
return 0;
error:
gcry_cipher_close(hd);
return -1;
#endif
}
/* -------------------------- IMPLEMENTATION -------------------------------- */
static int
client_setup_new(struct pair_setup_context *handle, const char *pin, pair_cb add_cb, void *cb_arg, const char *device_id)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
if (!is_initialized())
return -1;
if (!pin)
return -1;
sctx->pin = strdup(pin);
if (!sctx->pin)
return -1;
return 0;
}
static void
client_setup_free(struct pair_setup_context *handle)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
srp_user_free(sctx->user);
free(sctx->pkB);
free(sctx->M2);
free(sctx->salt);
free(sctx->epk);
free(sctx->authtag);
free(sctx->pin);
}
static uint8_t *
client_setup_request1(size_t *len, struct pair_setup_context *handle)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
plist_t dict;
plist_t method;
plist_t user;
uint32_t uint32;
char *data = NULL; // Necessary to initialize because plist_to_bin() uses value
sctx->user = srp_user_new(HASH_SHA1, SRP_NG_2048, USERNAME, (unsigned char *)sctx->pin, strlen(sctx->pin), 0, 0);
dict = plist_new_dict();
method = plist_new_string("pin");
user = plist_new_string(USERNAME);
plist_dict_set_item(dict, "method", method);
plist_dict_set_item(dict, "user", user);
plist_to_bin(dict, &data, &uint32);
plist_free(dict);
*len = (size_t)uint32;
return (uint8_t *)data;
}
static uint8_t *
client_setup_request2(size_t *len, struct pair_setup_context *handle)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
plist_t dict;
plist_t pk;
plist_t proof;
const char *auth_username = NULL;
uint32_t uint32;
char *data = NULL;
// Calculate A
srp_user_start_authentication(sctx->user, &auth_username, &sctx->pkA, &sctx->pkA_len);
// Calculate M1 (client proof)
srp_user_process_challenge(sctx->user, (const unsigned char *)sctx->salt, sctx->salt_len, (const unsigned char *)sctx->pkB, sctx->pkB_len, &sctx->M1, &sctx->M1_len);
pk = plist_new_data((char *)sctx->pkA, sctx->pkA_len);
proof = plist_new_data((char *)sctx->M1, sctx->M1_len);
dict = plist_new_dict();
plist_dict_set_item(dict, "pk", pk);
plist_dict_set_item(dict, "proof", proof);
plist_to_bin(dict, &data, &uint32);
plist_free(dict);
*len = (size_t)uint32;
return (uint8_t *)data;
}
static uint8_t *
client_setup_request3(size_t *len, struct pair_setup_context *handle)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
plist_t dict;
plist_t epk;
plist_t authtag;
uint32_t uint32;
char *data = NULL;
const unsigned char *session_key;
int session_key_len;
unsigned char key[SHA512_DIGEST_LENGTH];
unsigned char iv[SHA512_DIGEST_LENGTH];
unsigned char encrypted[128]; // Alloc a bit extra - should only need 2*16
unsigned char tag[16];
const char *errmsg;
int ret;
session_key = srp_user_get_session_key(sctx->user, &session_key_len);
if (!session_key)
{
handle->errmsg = "Setup request 3: No valid session key";
return NULL;
}
ret = hash_ab(HASH_SHA512, key, (unsigned char *)AES_SETUP_KEY, strlen(AES_SETUP_KEY), session_key, session_key_len);
if (ret < 0)
{
handle->errmsg = "Setup request 3: Hashing of key string and shared secret failed";
return NULL;
}
ret = hash_ab(HASH_SHA512, iv, (unsigned char *)AES_SETUP_IV, strlen(AES_SETUP_IV), session_key, session_key_len);
if (ret < 0)
{
handle->errmsg = "Setup request 3: Hashing of iv string and shared secret failed";
return NULL;
}
iv[15]++; // Nonce?
/*
if (iv[15] == 0x00 || iv[15] == 0xff)
printf("- note that value of last byte is %d!\n", iv[15]);
*/
crypto_sign_keypair(sctx->public_key, sctx->private_key);
ret = encrypt_gcm(encrypted, sizeof(encrypted), tag, sctx->public_key, sizeof(sctx->public_key), key, iv, &errmsg);
if (ret < 0)
{
handle->errmsg = errmsg;
return NULL;
}
epk = plist_new_data((char *)encrypted, EPK_LENGTH);
authtag = plist_new_data((char *)tag, AUTHTAG_LENGTH);
dict = plist_new_dict();
plist_dict_set_item(dict, "epk", epk);
plist_dict_set_item(dict, "authTag", authtag);
plist_to_bin(dict, &data, &uint32);
plist_free(dict);
*len = (size_t)uint32;
return (uint8_t *)data;
}
static int
client_setup_response1(struct pair_setup_context *handle, const uint8_t *data, size_t data_len)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
plist_t dict;
plist_t pk;
plist_t salt;
plist_from_bin((const char *)data, data_len, &dict);
pk = plist_dict_get_item(dict, "pk");
salt = plist_dict_get_item(dict, "salt");
if (!pk || !salt)
{
handle->errmsg = "Setup response 1: Missing pk or salt";
plist_free(dict);
return -1;
}
plist_get_data_val(pk, (char **)&sctx->pkB, &sctx->pkB_len); // B
plist_get_data_val(salt, (char **)&sctx->salt, &sctx->salt_len);
plist_free(dict);
return 0;
}
static int
client_setup_response2(struct pair_setup_context *handle, const uint8_t *data, size_t data_len)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
plist_t dict;
plist_t proof;
plist_from_bin((const char *)data, data_len, &dict);
proof = plist_dict_get_item(dict, "proof");
if (!proof)
{
handle->errmsg = "Setup response 2: Missing proof";
plist_free(dict);
return -1;
}
plist_get_data_val(proof, (char **)&sctx->M2, &sctx->M2_len); // M2
plist_free(dict);
// Check M2
srp_user_verify_session(sctx->user, (const unsigned char *)sctx->M2);
if (!srp_user_is_authenticated(sctx->user))
{
handle->errmsg = "Setup response 2: Server authentication failed";
return -1;
}
return 0;
}
static int
client_setup_response3(struct pair_setup_context *handle, const uint8_t *data, size_t data_len)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
plist_t dict;
plist_t epk;
plist_t authtag;
plist_from_bin((const char *)data, data_len, &dict);
epk = plist_dict_get_item(dict, "epk");
if (!epk)
{
handle->errmsg = "Setup response 3: Missing epk";
plist_free(dict);
return -1;
}
plist_get_data_val(epk, (char **)&sctx->epk, &sctx->epk_len);
authtag = plist_dict_get_item(dict, "authTag");
if (!authtag)
{
handle->errmsg = "Setup response 3: Missing authTag";
plist_free(dict);
return -1;
}
plist_get_data_val(authtag, (char **)&sctx->authtag, &sctx->authtag_len);
plist_free(dict);
assert(sizeof(handle->result.client_private_key) == sizeof(sctx->private_key));
assert(sizeof(handle->result.client_public_key) == sizeof(sctx->public_key));
memcpy(handle->result.client_private_key, sctx->private_key, sizeof(sctx->private_key));
memcpy(handle->result.client_public_key, sctx->public_key, sizeof(sctx->public_key));
handle->status = PAIR_STATUS_COMPLETED;
return 0;
}
static int
client_setup_result(struct pair_setup_context *handle)
{
struct pair_client_setup_context *sctx = &handle->sctx.client;
char *ptr;
int i;
// Last 32 bytes of the private key is the public key, so we don't need to
// explicitly export that
ptr = handle->result_str;
for (i = 0; i < sizeof(sctx->private_key); i++)
ptr += sprintf(ptr, "%02x", sctx->private_key[i]); // 2 x 64 bytes
*ptr = '\0';
return 0;
}
static int
client_verify_new(struct pair_verify_context *handle, const char *client_setup_keys, pair_cb cb, void *cb_arg, const char *device_id)
{
struct pair_client_verify_context *vctx = &handle->vctx.client;
char hex[] = { 0, 0, 0 };
size_t hexkey_len;
const char *ptr;
int i;
if (!is_initialized())
return -1;
if (!client_setup_keys)
return -1;
hexkey_len = strlen(client_setup_keys);
if (hexkey_len != 2 * sizeof(vctx->client_private_key))
return -1;
if (device_id && strlen(device_id) != 16)
return -1;
if (device_id)
memcpy(vctx->device_id, device_id, strlen(device_id));
ptr = client_setup_keys;
for (i = 0; i < sizeof(vctx->client_private_key); i++, ptr+=2)
{
hex[0] = ptr[0];
hex[1] = ptr[1];
vctx->client_private_key[i] = strtol(hex, NULL, 16);
}
crypto_sign_ed25519_sk_to_pk(vctx->client_public_key, vctx->client_private_key);
return 0;
}
static uint8_t *
client_verify_request1(size_t *len, struct pair_verify_context *handle)
{
struct pair_client_verify_context *vctx = &handle->vctx.client;
const uint8_t basepoint[32] = {9};
uint8_t *data;
int ret;
ret = crypto_scalarmult(vctx->client_eph_public_key, vctx->client_eph_private_key, basepoint);
if (ret < 0)
{
handle->errmsg = "Verify request 1: Curve 25519 returned an error";
return NULL;
}
*len = 4 + sizeof(vctx->client_eph_public_key) + sizeof(vctx->client_public_key);
data = calloc(1, *len);
if (!data)
{
handle->errmsg = "Verify request 1: Out of memory";
return NULL;
}
data[0] = 1; // Magic
memcpy(data + 4, vctx->client_eph_public_key, sizeof(vctx->client_eph_public_key));
memcpy(data + 4 + sizeof(vctx->client_eph_public_key), vctx->client_public_key, sizeof(vctx->client_public_key));
return data;
}
static uint8_t *
client_verify_request2(size_t *len, struct pair_verify_context *handle)
{
struct pair_client_verify_context *vctx = &handle->vctx.client;
uint8_t shared_secret[crypto_scalarmult_BYTES];
uint8_t key[SHA512_DIGEST_LENGTH];
uint8_t iv[SHA512_DIGEST_LENGTH];
uint8_t encrypted[128]; // Alloc a bit extra, should only really need size of public key len
uint8_t signature[crypto_sign_BYTES];
uint8_t *data;
int ret;
const char *errmsg;
*len = sizeof(vctx->client_eph_public_key) + sizeof(vctx->server_eph_public_key);
data = calloc(1, *len);
if (!data)
{
handle->errmsg = "Verify request 2: Out of memory";
return NULL;
}
memcpy(data, vctx->client_eph_public_key, sizeof(vctx->client_eph_public_key));
memcpy(data + sizeof(vctx->client_eph_public_key), vctx->server_eph_public_key, sizeof(vctx->server_eph_public_key));
crypto_sign_detached(signature, NULL, data, *len, vctx->client_private_key);
free(data);
ret = crypto_scalarmult(shared_secret, vctx->client_eph_private_key, vctx->server_eph_public_key);
if (ret < 0)
{
handle->errmsg = "Verify request 2: Curve 25519 returned an error";
return NULL;
}
ret = hash_ab(HASH_SHA512, key, (unsigned char *)AES_VERIFY_KEY, strlen(AES_VERIFY_KEY), shared_secret, sizeof(shared_secret));
if (ret < 0)
{
handle->errmsg = "Verify request 2: Hashing of key string and shared secret failed";
return NULL;
}
ret = hash_ab(HASH_SHA512, iv, (unsigned char *)AES_VERIFY_IV, strlen(AES_VERIFY_IV), shared_secret, sizeof(shared_secret));
if (ret < 0)
{
handle->errmsg = "Verify request 2: Hashing of iv string and shared secret failed";
return NULL;
}
ret = encrypt_ctr(encrypted, sizeof(encrypted), vctx->server_fruit_public_key, sizeof(vctx->server_fruit_public_key), signature, sizeof(signature), key, iv, &errmsg);
if (ret < 0)
{
handle->errmsg = errmsg;
return NULL;
}
*len = 4 + sizeof(vctx->server_fruit_public_key);
data = calloc(1, *len);
if (!data)
{
handle->errmsg = "Verify request 2: Out of memory";
return NULL;
}