aboutsummaryrefslogtreecommitdiff
path: root/src/noscrypt.c
blob: f3c28cbc728893352753f485af19ee0601ec94c1 (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
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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
/*
* Copyright (c) 2024 Vaughn Nugent
*
* Package: noscrypt
* File: noscrypt.c
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* of the License, or  (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with noscrypt. If not, see http://www.gnu.org/licenses/.
*/

#include "noscrypt.h"

#include "nc-util.h"
#include "hkdf.h"
#include "nc-crypto.h"

#include <secp256k1/secp256k1_ecdh.h>
#include <secp256k1/secp256k1_schnorrsig.h>

/*
* Local macro for secure zero buffer fill
*/
#define ZERO_FILL(x, size) ncCryptoSecureZero(x, size) 

/*
* Validation macros
*/

#ifndef NC_INPUT_VALIDATION_OFF
	#define CHECK_INVALID_ARG(x, argPos) if(x == NULL) return NCResultWithArgPosition(E_INVALID_ARG, argPos);
	#define CHECK_NULL_ARG(x, argPos) if(x == NULL) return NCResultWithArgPosition(E_NULL_PTR, argPos);
	#define CHECK_ARG_RANGE(x, min, max, argPos) if(x < min || x > max) return NCResultWithArgPosition(E_ARGUMENT_OUT_OF_RANGE, argPos);
#else
	/* empty macros */
	#define CHECK_INVALID_ARG(x)
	#define CHECK_NULL_ARG(x, argPos) 
	#define CHECK_ARG_RANGE(x, min, max, argPos) 
#endif /* !NC_DISABLE_INPUT_VALIDATION */

#define CHECK_CONTEXT_STATE(ctx, argPos) CHECK_INVALID_ARG(ctx->secpCtx, argPos)

/*
* Actual, private defintion of the NCContext structure 
* to allow for future development and ABI backords 
* compatability.
*/
struct nc_ctx_struct {

	void* secpCtx;

};

/*
* The Nip44 constant salt
* https://github.com/nostr-protocol/nips/blob/master/44.md#encryption
*/
static const uint8_t Nip44ConstantSalt[8] = { 0x6e, 0x69, 0x70, 0x34, 0x34, 0x2d, 0x76, 0x32 };

static struct nc_ctx_struct _ncSharedCtx;

struct shared_secret {
	uint8_t value[NC_SHARED_SEC_SIZE];
};

struct conversation_key {
	uint8_t value[NC_CONV_KEY_SIZE];
};

struct message_key {
	uint8_t value[NC_MESSAGE_KEY_SIZE];
};

/*
* The following struct layout is exactly the same as 
* the message key, they may be typecasted to each other.
* as long as the size is the same.
*/
struct nc_expand_keys {
	uint8_t chacha_key[CHACHA_KEY_SIZE];
	uint8_t chacha_nonce[CHACHA_NONCE_SIZE];
	uint8_t hmac_key[NC_HMAC_KEY_SIZE];
};


/* Pointer typecast must work between expanded keys 
* and message key, size must be identical to work 
*/
STATIC_ASSERT(sizeof(struct nc_expand_keys) == sizeof(struct message_key), "Expected struct nc_expand_keys to be the same size as struct message_key")

/*
* Check that the fallback hkdf extract internal buffer is large enough
* for full converstation key buffers 
*/
STATIC_ASSERT(HKDF_IN_BUF_SIZE >= NC_CONV_KEY_SIZE + 8, "HKDF Buffer size is too small for safe HKDF operations")

/*
* Internal helper functions to do common structure conversions
*/

static _nc_fn_inline int _convertToXonly(
	const NCContext* ctx, 
	const NCPublicKey* compressedPubKey, 
	secp256k1_xonly_pubkey* xonly
)
{
	DEBUG_ASSERT2(ctx != NULL, "Expected valid context")
	DEBUG_ASSERT2(compressedPubKey != NULL, "Expected a valid public 32byte key structure")
	DEBUG_ASSERT2(xonly != NULL, "Expected valid X-only secp256k1 public key structure ")

	/* Parse the public key into the x-only structure */
	return secp256k1_xonly_pubkey_parse(ctx->secpCtx, xonly, compressedPubKey->key);
}

static int _convertToPubKey(const NCContext* ctx, const NCPublicKey* compressedPubKey, secp256k1_pubkey* pubKey)
{
	int result;
	uint8_t compressed[sizeof(NCPublicKey) + 1];

	DEBUG_ASSERT2(ctx != NULL, "Expected valid context")
	DEBUG_ASSERT2(compressedPubKey != NULL, "Expected a valid public 32byte key structure")
	DEBUG_ASSERT2(pubKey != NULL, "Expected valid secp256k1 public key structure")

	/* Set the first byte to 0x02 to indicate a compressed public key */
	compressed[0] = BIP340_PUBKEY_HEADER_BYTE;

	/* Copy the compressed public key data into a new buffer (offset by 1 to store the header byte) */
	MEMMOV((compressed + 1), compressedPubKey, sizeof(NCPublicKey));

	result = secp256k1_ec_pubkey_parse(ctx->secpCtx, pubKey, compressed, sizeof(compressed));
	
	ZERO_FILL(compressed, sizeof(compressed));

	return result;
}

static _nc_fn_inline int _convertFromXonly(
	const NCContext* ctx, 
	const secp256k1_xonly_pubkey* xonly, 
	NCPublicKey* compressedPubKey
)
{
	DEBUG_ASSERT2(ctx != NULL, "Expected valid context")
	DEBUG_ASSERT2(xonly != NULL, "Expected valid X-only secp256k1 public key structure.")
	DEBUG_ASSERT2(compressedPubKey != NULL, "Expected a valid public 32byte pubkey structure")

	return secp256k1_xonly_pubkey_serialize(ctx->secpCtx, compressedPubKey->key, xonly);
}

/*
* IMPL NOTES:
* This callback function will be invoked by the ecdh function to hash the shared point.
*
* For nostr, this operation is defined in the new NIP-44 spec here:
* https://github.com/nostr-protocol/nips/blob/master/44.md#encryption
*
* The x coordinate of the shared point is copied directly into the output buffer. No hashing is
* performed here. The y coordinate is not used, and for this implementation, there is no data
* pointer.
*/
static int _edhHashFuncInternal(
	unsigned char* output,
	const uint8_t* x32,
	const uint8_t* y32,
	void* data
)
{
	((void)y32);	/* unused for nostr */
	((void)data);

	DEBUG_ASSERT2(output != NULL, "Expected valid output buffer")
	DEBUG_ASSERT2(x32 != NULL, "Expected a valid public 32byte x-coodinate buffer")

	/* Copy the x coordinate of the shared point into the output buffer */
	MEMMOV(output, x32, 32);

	return 32;	/* Return the number of bytes written to the output buffer */
}

static NCResult _computeSharedSecret(
	const NCContext* ctx,
	const NCSecretKey* sk,
	const NCPublicKey* otherPk,
	struct shared_secret* sharedPoint
)
{
	int result;
	secp256k1_pubkey pubKey;

	DEBUG_ASSERT(ctx != NULL)
	DEBUG_ASSERT(sk != NULL)
	DEBUG_ASSERT(otherPk != NULL)
	DEBUG_ASSERT(sharedPoint != NULL)

	/* Recover pubkey from compressed public key data */
	if (_convertToPubKey(ctx, otherPk, &pubKey) != 1)
	{
		return E_INVALID_ARG;
	}

	/*
	* Compute the shared point using the ecdh function.
	*
	* The above callback is invoked to "compute" the hash (it
	* copies the x coord) and it does not use the data pointer
	* so it is set to NULL.
	*/
	result = secp256k1_ecdh(
		ctx->secpCtx,
		(uint8_t*)sharedPoint,
		&pubKey,
		sk->key,
		&_edhHashFuncInternal,
		NULL
	);
	
	ZERO_FILL(&pubKey, sizeof(pubKey));

	/* Result should be 1 on success */
	return result == 1 ? NC_SUCCESS : E_OPERATION_FAILED;
}

static _nc_fn_inline NCResult _computeConversationKey(
	const NCContext* ctx, 
	const struct shared_secret* sharedSecret,
	struct conversation_key* ck 
)
{
	cspan_t saltSpan, ikmSpan;
	
	DEBUG_ASSERT2(ctx != NULL, "Expected valid context")
	DEBUG_ASSERT2(sharedSecret != NULL, "Expected a valid shared-point")
	DEBUG_ASSERT2(ck != NULL, "Expected a valid conversation key")

	ncSpanInitC(&saltSpan, Nip44ConstantSalt, sizeof(Nip44ConstantSalt));
	ncSpanInitC(&ikmSpan, sharedSecret->value, NC_SHARED_SEC_SIZE);
	
	return ncCryptoSha256HkdfExtract(&saltSpan, &ikmSpan, ck->value) == CSTATUS_OK ? NC_SUCCESS : E_OPERATION_FAILED;
}


/*
* Explode the hkdf into the chacha key, chacha nonce, and hmac key.
*/
static _nc_fn_inline const struct nc_expand_keys* _expandKeysFromHkdf(const struct message_key* hkdf)
{
	return (const struct nc_expand_keys*)hkdf;
}

static cstatus_t _chachaEncipher(const struct nc_expand_keys* keys, NCEncryptionArgs* args)
{
	DEBUG_ASSERT2(keys != NULL, "Expected valid keys")
	DEBUG_ASSERT2(args != NULL, "Expected valid encryption args")

	return ncCryptoChacha20(
		keys->chacha_key,
		keys->chacha_nonce,
		args->inputData,		/* Input data */
		args->outputData,		/* Output data */
		args->dataSize			/* Data size (input and output are assumed to be the same size) */
	);
}

static _nc_fn_inline cstatus_t _getMessageKey(
	const struct conversation_key* converstationKey, 
	cspan_t nonce,
	struct message_key* messageKey
)
{
	cspan_t prkSpan;
	span_t okmSpan;

	DEBUG_ASSERT2(converstationKey != NULL, "Expected valid conversation key")
	DEBUG_ASSERT2(messageKey != NULL, "Expected valid message key buffer")

	ncSpanInitC(&prkSpan, converstationKey->value, sizeof(struct conversation_key));	/* Conversation key is the input key */
	ncSpanInit(&okmSpan, messageKey->value, sizeof(struct message_key));				/* Output produces a message key (write it directly to struct memory) */
	
	/* Nonce is the info */
	return ncCryptoSha256HkdfExpand(&prkSpan, &nonce, &okmSpan);
}

static _nc_fn_inline NCResult _encryptNip44Ex(
	const NCContext* ctx, 
	const struct conversation_key* ck, 
	uint8_t* hmacKey,
	NCEncryptionArgs* args
)
{
	NCResult result;
	cspan_t nonceSpan;
	struct message_key messageKey;
	const struct nc_expand_keys* expandedKeys;

	DEBUG_ASSERT2(ctx != NULL,		"Expected valid context")
	DEBUG_ASSERT2(ck != NULL,		"Expected valid conversation key")
	DEBUG_ASSERT2(args != NULL,		"Expected valid encryption args")
	DEBUG_ASSERT2(hmacKey != NULL,	"Expected valid hmac key buffer")

	result = NC_SUCCESS;

	ncSpanInitC(&nonceSpan, args->nonceData, NC_ENCRYPTION_NONCE_SIZE);
	
	/* Message key will be derrived on every encryption call */
	if (_getMessageKey(ck, nonceSpan, &messageKey) != CSTATUS_OK)
	{
		result = E_OPERATION_FAILED;
		goto Cleanup;
	}

	/* Split apart the message key into it's expanded form so components can be extracted */
	expandedKeys = _expandKeysFromHkdf(&messageKey);

	/* Copy the hmac key into the args */
	MEMMOV(hmacKey, expandedKeys->hmac_key, NC_HMAC_KEY_SIZE);

	/* CHACHA20 (the result will be 0 on success) */
	if (_chachaEncipher(expandedKeys, args) != CSTATUS_OK)
	{
		result = E_OPERATION_FAILED;
	}

Cleanup:
	ZERO_FILL(&messageKey, sizeof(messageKey));

	return result;
}

static _nc_fn_inline NCResult _decryptNip44Ex(const NCContext* ctx, const struct conversation_key* ck, NCEncryptionArgs* args)
{
	NCResult result;
	cspan_t nonceSpan;
	struct message_key messageKey;
	const struct nc_expand_keys* cipherKeys;

	DEBUG_ASSERT2(ctx != NULL, "Expected valid context")
	DEBUG_ASSERT2(ck != NULL, "Expected valid conversation key")
	DEBUG_ASSERT2(args != NULL, "Expected valid encryption args")

	result = NC_SUCCESS;

	ncSpanInitC(&nonceSpan, args->nonceData, NC_ENCRYPTION_NONCE_SIZE);
	
	if (_getMessageKey(ck, nonceSpan, &messageKey) != CSTATUS_OK)
	{
		result = E_OPERATION_FAILED;
		goto Cleanup;
	}

	/* Expand the keys from the hkdf so we can use them in the cipher */
	cipherKeys = _expandKeysFromHkdf(&messageKey);

	/* CHACHA20 (the result will be 0 on success) */
	if (_chachaEncipher(cipherKeys, args) != CSTATUS_OK)
	{
		result = E_OPERATION_FAILED;
	}

Cleanup:
	ZERO_FILL(&messageKey, sizeof(messageKey));

	return result;
}

static _nc_fn_inline cstatus_t _computeHmac(const uint8_t key[NC_HMAC_KEY_SIZE], cspan_t payload, sha256_t hmacOut)
{
	cspan_t keySpan;

	DEBUG_ASSERT2(key != NULL,		"Expected valid hmac key")
	DEBUG_ASSERT2(hmacOut != NULL,	"Expected valid hmac output buffer")

	ncSpanInitC(&keySpan, key, NC_HMAC_KEY_SIZE);

	return ncCryptoHmacSha256(&keySpan, &payload, hmacOut);
}

static NCResult _verifyMacEx(
	const NCContext* ctx,
	const uint8_t conversationKey[NC_CONV_KEY_SIZE],
	NCMacVerifyArgs* args
)
{
	NCResult result;
	cspan_t payloadSpan, nonceSpan;
	sha256_t hmacOut;
	const struct nc_expand_keys* keys;
	struct message_key messageKey;
 
	DEBUG_ASSERT2(ctx != NULL, "Expected valid context")
	DEBUG_ASSERT2(conversationKey != NULL, "Expected valid conversation key")
	DEBUG_ASSERT2(args != NULL, "Expected valid mac verification args")

	ncSpanInitC(&nonceSpan, args->nonce32, NC_ENCRYPTION_NONCE_SIZE);
	ncSpanInitC(&payloadSpan, args->payload, args->payloadSize);

	/*
	* Message key is again required for the hmac verification
	*/

	if (_getMessageKey((struct conversation_key*)conversationKey, nonceSpan, &messageKey) != CSTATUS_OK)
	{
		result = E_OPERATION_FAILED;
		goto Cleanup;
	}

	/* Expand keys to get the hmac-key */
	keys = _expandKeysFromHkdf(&messageKey);

	/*
	* Compute the hmac of the data using the computed hmac key
	*/
	if (_computeHmac(keys->hmac_key, payloadSpan, hmacOut) != CSTATUS_OK)
	{
		result = E_OPERATION_FAILED;
		goto Cleanup;
	}

	/* constant time compare the macs */
	result = ncCryptoFixedTimeComp(hmacOut, args->mac32, NC_ENCRYPTION_MAC_SIZE) == 0 ? NC_SUCCESS : E_OPERATION_FAILED;

Cleanup:
	ZERO_FILL(&messageKey, sizeof(messageKey));
	ZERO_FILL(hmacOut, sizeof(hmacOut));

	return result;
}

/*
* EXTERNAL API FUNCTIONS
*/


NC_EXPORT NCResult NC_CC NCResultWithArgPosition(NCResult err, uint8_t argPosition)
{
	return -(((NCResult)argPosition << NC_ARG_POSITION_OFFSET) | -err);
}

NC_EXPORT int NC_CC NCParseErrorCode(NCResult result, uint8_t* argPositionOut)
{
	NCResult asPositive;
	int code;

	/* convert result to a positive value*/
	asPositive = -result;

	/* Get the error code from the lower 8 bits and the argument position from the upper 8 bits*/
	code = -(asPositive & NC_ERROR_CODE_MASK);

	/* Allow argument position assignment to be null */
	if (argPositionOut) 
	{
		*argPositionOut = (asPositive >> NC_ARG_POSITION_OFFSET) & 0xFF;
	}

	return code;
}

/*	=============================
*	
*		Context functions
* 
*	============================= 
*/

NC_EXPORT uint32_t NC_CC NCGetContextStructSize(void) 
{
	return sizeof(NCContext);
}

NC_EXPORT NCContext* NC_CC NCGetSharedContext(void)
{
	/*Return the global address of the shared context structure */
	return &_ncSharedCtx;
}

NC_EXPORT NCResult NC_CC NCInitContext(
	NCContext* ctx, 
	const uint8_t entropy[NC_CONTEXT_ENTROPY_SIZE]
)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_NULL_ARG(entropy, 1)

	ZERO_FILL(ctx, sizeof(NCContext));

	ctx->secpCtx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);

	/* 
	* Randomize once on init, users can call reinit to 
	* randomize again as needed.
	*/
	return secp256k1_context_randomize(ctx->secpCtx, entropy) ? NC_SUCCESS : E_INVALID_ARG;
}

NC_EXPORT NCResult NC_CC NCReInitContext(
	NCContext* ctx, 
	const uint8_t entropy[NC_CONTEXT_ENTROPY_SIZE]
)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_NULL_ARG(entropy, 1)
	CHECK_CONTEXT_STATE(ctx, 0)

	/* Only randomize again */
	return secp256k1_context_randomize(ctx->secpCtx, entropy) ? NC_SUCCESS : E_INVALID_ARG;
}

NC_EXPORT NCResult NC_CC NCDestroyContext(NCContext* ctx)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)

	/* Destroy secp256k1 context */
	secp256k1_context_destroy(ctx->secpCtx);

	/* Wipe the context */
	ZERO_FILL(ctx, sizeof(NCContext));

	return NC_SUCCESS;
}

/*	=============================
*
*		ECDSA functions
*
*	=============================
*/

NC_EXPORT NCResult NC_CC NCGetPublicKey(
	const NCContext* ctx, 
	const NCSecretKey* sk, 
	NCPublicKey* pk
)
{
	int result;
	secp256k1_keypair keyPair;
	secp256k1_xonly_pubkey xonly;

	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(pk, 2)

	if (secp256k1_keypair_create(ctx->secpCtx, &keyPair, sk->key) != 1)
	{
		return E_INVALID_ARG;
	}

	/* Generate the x-only public key, docs say this should always return 1 */
	result = secp256k1_keypair_xonly_pub(ctx->secpCtx, &xonly, NULL, &keyPair);
	DEBUG_ASSERT2(result == 1, "Expected x-only kepair to ALWAYS return 1")

	/* Convert to compressed pubkey */
	result = _convertFromXonly(ctx, &xonly, pk);
	DEBUG_ASSERT2(result == 1, "Expected x-only pubkey serialize to return 1")

	/* Clean out keypair */
	ZERO_FILL(&keyPair, sizeof(keyPair));
	ZERO_FILL(&xonly, sizeof(xonly));

	return NC_SUCCESS;
}

NC_EXPORT NCResult NC_CC NCValidateSecretKey(const NCContext* ctx, const NCSecretKey* sk)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_CONTEXT_STATE(ctx, 0)

	/* Validate the secret key */
	return secp256k1_ec_seckey_verify(ctx->secpCtx, sk->key) == 1 
		? NC_SUCCESS 
		: E_OPERATION_FAILED;
}

/* Ecdsa Functions */

NC_EXPORT NCResult NC_CC NCSignDigest(
	const NCContext* ctx, 
	const NCSecretKey* sk, 
	const uint8_t random32[32], 
	const uint8_t digest32[32], 
	uint8_t sig64[64]
)
{
	int result;
	secp256k1_keypair keyPair;
	secp256k1_xonly_pubkey xonly;	

	/* Validate arguments */
	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(random32, 2)
	CHECK_NULL_ARG(digest32, 3)
	CHECK_NULL_ARG(sig64, 4)

	/* Fill keypair structure from the callers secret key */
	if (secp256k1_keypair_create(ctx->secpCtx, &keyPair, sk->key) != 1)
	{
		return E_INVALID_ARG;
	}

	/* Sign the digest */
	result = secp256k1_schnorrsig_sign32(ctx->secpCtx, sig64, digest32, &keyPair, random32);
	DEBUG_ASSERT2(result == 1, "Expected schnorr signature to return 1");

	/* x-only public key from keypair so the signature can be verified */
	result = secp256k1_keypair_xonly_pub(ctx->secpCtx, &xonly, NULL, &keyPair);
	DEBUG_ASSERT2(result == 1, "Expected x-only public key to ALWAYS return 1");

	/* Verify the signature is valid */
	result = secp256k1_schnorrsig_verify(ctx->secpCtx, sig64, digest32, 32, &xonly);
	
	ZERO_FILL(&keyPair, sizeof(keyPair));
	ZERO_FILL(&xonly, sizeof(xonly));

	return result == 1 ? NC_SUCCESS : E_INVALID_ARG;
}

NC_EXPORT NCResult NC_CC NCSignData(
	const NCContext* ctx,
	const NCSecretKey* sk,
	const uint8_t random32[32],
	const uint8_t* data,
	uint32_t dataSize,
	uint8_t sig64[64]
)
{
	cspan_t dataSpan;
	sha256_t digest;	

	/* Double check is required because arg position differs */
	CHECK_NULL_ARG(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(random32, 2)
	CHECK_NULL_ARG(data, 3)
	CHECK_ARG_RANGE(dataSize, 1, UINT32_MAX, 4)
	CHECK_NULL_ARG(sig64, 5)

	ncSpanInitC(&dataSpan, data, dataSize);

	/* Compute sha256 of the data before signing */
	if(ncCryptoDigestSha256(&dataSpan, digest) != CSTATUS_OK)
	{
		return E_INVALID_ARG;
	}

	/* Sign the freshly computed digest */
	return NCSignDigest(ctx, sk, random32, digest, sig64);
}

NC_EXPORT NCResult NC_CC NCVerifyDigest(
	const NCContext* ctx,
	const NCPublicKey* pk,
	const uint8_t digest32[32],
	const uint8_t sig64[64]
)
{
	int result;
	secp256k1_xonly_pubkey xonly;

	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(pk, 1)
	CHECK_NULL_ARG(digest32, 2)
	CHECK_NULL_ARG(sig64, 3)	

	/* recover the x-only key from a compressed public key */
	if(_convertToXonly(ctx, pk, &xonly) != 1)
	{
		return E_INVALID_ARG;
	}

	result = secp256k1_schnorrsig_verify(ctx->secpCtx, sig64, digest32, 32, &xonly);
	
	ZERO_FILL(&xonly, sizeof(xonly));

	return result == 1 ? NC_SUCCESS : E_INVALID_ARG;
}

NC_EXPORT NCResult NC_CC NCVerifyData(
	const NCContext* ctx,
	const NCPublicKey* pk,
	const uint8_t* data,
	const uint32_t dataSize,
	const uint8_t sig64[64]
)
{
	sha256_t digest;
	cspan_t dataSpan;

	CHECK_NULL_ARG(ctx, 0)
	CHECK_NULL_ARG(pk, 1)
	CHECK_NULL_ARG(data, 2)
	CHECK_ARG_RANGE(dataSize, 1, UINT32_MAX, 3)
	CHECK_NULL_ARG(sig64, 4)

	ncSpanInitC(&dataSpan, data, dataSize);

	/* Compute sha256 of the data before verifying */
	if (ncCryptoDigestSha256(&dataSpan, digest) != CSTATUS_OK)
	{
		return E_INVALID_ARG;
	}

	return NCVerifyDigest(ctx, pk, digest, sig64);
}

/*	=============================
*
*		ECDH functions
*
*	=============================
*/

NC_EXPORT NCResult NC_CC NCGetSharedSecret(
	const NCContext* ctx, 
	const NCSecretKey* sk, 
	const NCPublicKey* otherPk, 
	uint8_t sharedPoint[NC_SHARED_SEC_SIZE]
)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(otherPk, 2)
	CHECK_NULL_ARG(sharedPoint, 3)	

	return _computeSharedSecret(ctx, sk, otherPk, (struct shared_secret*)sharedPoint);
}

NC_EXPORT NCResult NC_CC NCGetConversationKeyEx(
	const NCContext* ctx,
	const uint8_t sharedPoint[NC_SHARED_SEC_SIZE],
	uint8_t conversationKey[NC_CONV_KEY_SIZE]
)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sharedPoint, 1)
	CHECK_NULL_ARG(conversationKey, 2)	

	/* Cast the shared point to the shared secret type */
	return _computeConversationKey(
		ctx,
		(struct shared_secret*)sharedPoint, 
		(struct conversation_key*)conversationKey
	);
}

NC_EXPORT NCResult NC_CC NCGetConversationKey(
	const NCContext* ctx,
	const NCSecretKey* sk,
	const NCPublicKey* pk,
	uint8_t conversationKey[NC_CONV_KEY_SIZE]
)
{
	NCResult result;
	struct shared_secret sharedSecret;

	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(pk, 2)
	CHECK_NULL_ARG(conversationKey, 3)

	/* Compute the shared point */
	if ((result = _computeSharedSecret(ctx, sk, pk, &sharedSecret)) != NC_SUCCESS)
	{
		goto Cleanup;
	}

	result = _computeConversationKey(ctx, &sharedSecret, (struct conversation_key*)conversationKey);

Cleanup:
	/* Clean up sensitive data */
	ZERO_FILL(&sharedSecret, sizeof(sharedSecret));

	return result;
}

NC_EXPORT NCResult NC_CC NCEncryptEx(
	const NCContext* ctx, 
	const uint8_t conversationKey[NC_CONV_KEY_SIZE], 
	NCEncryptionArgs* args
)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(conversationKey, 1)
	CHECK_NULL_ARG(args, 2)

	/* Validte ciphertext/plaintext */
	CHECK_INVALID_ARG(args->inputData, 2)
	CHECK_INVALID_ARG(args->outputData, 2)
	CHECK_INVALID_ARG(args->nonceData, 2)
	CHECK_INVALID_ARG(args->keyData, 2)
	CHECK_ARG_RANGE(args->dataSize, NIP44_MIN_ENC_MESSAGE_SIZE, NIP44_MAX_ENC_MESSAGE_SIZE, 2)	

	switch (args->version) 
	{
		/* TODO: Implement nip04 */
		case NC_ENC_VERSION_NIP04:
			return E_VERSION_NOT_SUPPORTED;

		case NC_ENC_VERSION_NIP44:
			return _encryptNip44Ex(ctx, (struct conversation_key*)conversationKey, args->keyData, args);

		default:
			return E_VERSION_NOT_SUPPORTED;
	}

}

NC_EXPORT NCResult NC_CC NCEncrypt(
	const NCContext* ctx, 
	const NCSecretKey* sk, 
	const NCPublicKey* pk,
	NCEncryptionArgs* args
)
{	
	NCResult result;
	struct shared_secret sharedSecret;
	struct conversation_key conversationKey;	

	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(pk, 2)
	CHECK_NULL_ARG(args, 3)

	/* Validate input/output data */
	CHECK_INVALID_ARG(args->inputData, 3)
	CHECK_INVALID_ARG(args->outputData, 3)
	CHECK_INVALID_ARG(args->nonceData, 3)

	result = E_OPERATION_FAILED;

	switch(args->version)
	{		
		case NC_ENC_VERSION_NIP44:
		{
			/* Mac key output is only needed for nip44 */
			CHECK_INVALID_ARG(args->keyData, 3)
			CHECK_ARG_RANGE(args->dataSize, NIP44_MIN_ENC_MESSAGE_SIZE, NIP44_MAX_ENC_MESSAGE_SIZE, 3)

			/* Compute the shared point */
			if ((result = _computeSharedSecret(ctx, sk, pk, &sharedSecret)) != NC_SUCCESS)
			{
				goto Cleanup;
			}

			/* Compute the conversation key from secret and pubkic keys */
			if ((result = _computeConversationKey(ctx, &sharedSecret, &conversationKey)) != NC_SUCCESS)
			{
				goto Cleanup;
			}

			result = _encryptNip44Ex(ctx, &conversationKey, args->keyData, args);
		}

		break;

		/* At the moment nip04 compatability is not supported */
		case NC_ENC_VERSION_NIP04:
		default:
			result = E_VERSION_NOT_SUPPORTED;
			break;
	}
	

Cleanup:
	/* Clean up sensitive data */
	ZERO_FILL(&sharedSecret, sizeof(sharedSecret));
	ZERO_FILL(&conversationKey, sizeof(conversationKey));

	return result;
}

NC_EXPORT NCResult NC_CC NCDecryptEx(
	const NCContext* ctx,
	const uint8_t conversationKey[NC_CONV_KEY_SIZE],
	NCEncryptionArgs* args
)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(conversationKey, 1)
	CHECK_NULL_ARG(args, 2)

	/* Validte ciphertext/plaintext */
	CHECK_INVALID_ARG(args->inputData, 2)
	CHECK_INVALID_ARG(args->outputData, 2)
	CHECK_INVALID_ARG(args->nonceData, 2)
	CHECK_ARG_RANGE(args->dataSize, NIP44_MIN_ENC_MESSAGE_SIZE, NIP44_MAX_ENC_MESSAGE_SIZE, 2)

	switch (args->version)
	{
	case NC_ENC_VERSION_NIP44:
		return _decryptNip44Ex(ctx, (struct conversation_key*)conversationKey, args);

	case NC_ENC_VERSION_NIP04:
	default:
		return E_VERSION_NOT_SUPPORTED;
	}
}

NC_EXPORT NCResult NC_CC NCDecrypt(
	const NCContext* ctx,
	const NCSecretKey* sk,
	const NCPublicKey* pk,
	NCEncryptionArgs* args
)
{
	NCResult result;
	struct shared_secret sharedSecret;
	struct conversation_key conversationKey;

	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(pk, 2)
	CHECK_NULL_ARG(args, 3)

	/* Validte ciphertext/plaintext */
	CHECK_INVALID_ARG(args->inputData, 3)
	CHECK_INVALID_ARG(args->outputData, 3)
	CHECK_INVALID_ARG(args->nonceData, 3)
	CHECK_ARG_RANGE(args->dataSize, NIP44_MIN_ENC_MESSAGE_SIZE, NIP44_MAX_ENC_MESSAGE_SIZE, 3)

	result = E_OPERATION_FAILED;

	switch (args->version)
	{
	case NC_ENC_VERSION_NIP44:
	{
		if ((result = _computeSharedSecret(ctx, sk, pk, &sharedSecret)) != NC_SUCCESS)
		{
			goto Cleanup;
		}

		if ((result = _computeConversationKey(ctx, &sharedSecret, &conversationKey)) != NC_SUCCESS)
		{
			goto Cleanup;
		}

		result = _decryptNip44Ex(ctx, &conversationKey, args);
	}
	break;

	case NC_ENC_VERSION_NIP04:
	default:
		result = E_VERSION_NOT_SUPPORTED;
		break;
	}

Cleanup:
	/* Clean up sensitive data */
	ZERO_FILL(&sharedSecret, sizeof(sharedSecret));
	ZERO_FILL(&conversationKey, sizeof(conversationKey));

	return result;
}

NC_EXPORT NCResult NCComputeMac(
	const NCContext* ctx,
	const uint8_t hmacKey[NC_HMAC_KEY_SIZE],
	const uint8_t* payload,
	uint32_t payloadSize,
	uint8_t hmacOut[NC_ENCRYPTION_MAC_SIZE]
)
{
	cspan_t payloadSpan;

	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(hmacKey, 1)
	CHECK_NULL_ARG(payload, 2)
	CHECK_ARG_RANGE(payloadSize, 1, UINT32_MAX, 3)
	CHECK_NULL_ARG(hmacOut, 4)
	
	ncSpanInitC(&payloadSpan, payload, payloadSize);

	/*
	* Compute the hmac of the data using the supplied hmac key
	*/
	return _computeHmac(hmacKey, payloadSpan, hmacOut) == CSTATUS_OK ? NC_SUCCESS : E_OPERATION_FAILED;
}


NC_EXPORT NCResult NC_CC NCVerifyMacEx(
	const NCContext* ctx,
	const uint8_t conversationKey[NC_CONV_KEY_SIZE],
	NCMacVerifyArgs* args
)
{
	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(conversationKey, 1)
	CHECK_NULL_ARG(args, 2)

	CHECK_INVALID_ARG(args->mac32, 2)
	CHECK_INVALID_ARG(args->payload, 2)
	CHECK_INVALID_ARG(args->nonce32, 2)
	CHECK_ARG_RANGE(args->payloadSize, NIP44_MIN_ENC_MESSAGE_SIZE, NIP44_MAX_ENC_MESSAGE_SIZE, 2)	

	return _verifyMacEx(ctx, conversationKey, args);
}

NC_EXPORT NCResult NC_CC NCVerifyMac(
	const NCContext* ctx,
	const NCSecretKey* sk,
	const NCPublicKey* pk,
	NCMacVerifyArgs* args
)
{
	NCResult result;
	struct shared_secret sharedSecret;
	struct conversation_key conversationKey;

	CHECK_NULL_ARG(ctx, 0)
	CHECK_CONTEXT_STATE(ctx, 0)
	CHECK_NULL_ARG(sk, 1)
	CHECK_NULL_ARG(pk, 2)
	CHECK_NULL_ARG(args, 3)

	CHECK_INVALID_ARG(args->mac32, 3)
	CHECK_INVALID_ARG(args->payload, 3)
	CHECK_INVALID_ARG(args->nonce32, 3)
	CHECK_ARG_RANGE(args->payloadSize, NIP44_MIN_ENC_MESSAGE_SIZE, NIP44_MAX_ENC_MESSAGE_SIZE, 3)

	/* Computed the shared point so we can get the converstation key */
	if ((result = _computeSharedSecret(ctx, sk, pk, &sharedSecret)) != NC_SUCCESS)
	{
		goto Cleanup;
	}

	if ((result = _computeConversationKey(ctx, &sharedSecret, &conversationKey)) != NC_SUCCESS)
	{
		goto Cleanup;
	}

	result = _verifyMacEx(ctx, conversationKey.value, args);

Cleanup:
	/* Clean up sensitive data */
	ZERO_FILL(&sharedSecret, sizeof(sharedSecret));
	ZERO_FILL(&conversationKey, sizeof(conversationKey));

	return result;
}

#define ENSURE_ENC_MODE(args, mode) if(args->version != mode) return E_VERSION_NOT_SUPPORTED;

NC_EXPORT NCResult NCSetEncryptionPropertyEx(
	NCEncryptionArgs* args,
	uint32_t property,
	uint8_t* value,
	uint32_t valueLen
)
{

	CHECK_NULL_ARG(args, 0)
	CHECK_NULL_ARG(value, 2)

	switch (property)
	{
	case NC_ENC_SET_VERSION:

		/* Ensure version is proper length */
		CHECK_ARG_RANGE(valueLen, sizeof(uint32_t), sizeof(uint32_t), 2)

		args->version = *((uint32_t*)value);

		return NC_SUCCESS;

	case NC_ENC_SET_NIP04_IV:
		/*
		* The safest way to store the nip04 IV is in the nonce
		* field. An IV is essentially a nonce. A secure random
		* number used to encrypt the first block of a CBC chain.
		*/

		CHECK_ARG_RANGE(valueLen, AES_IV_SIZE, UINT32_MAX, 3)

		ENSURE_ENC_MODE(args, NC_ENC_VERSION_NIP04)

		args->nonceData = value;

		return NC_SUCCESS;


	case NC_ENC_SET_NIP04_KEY:
		/*
		* The AES key is stored in the hmac key field, since
		* it won't be used for the operating and should be the same size
		* as the hmac key.
		*/

		CHECK_ARG_RANGE(valueLen, AES_KEY_SIZE, UINT32_MAX, 3)

		ENSURE_ENC_MODE(args, NC_ENC_VERSION_NIP04)

		args->keyData = value;

		return NC_SUCCESS;

	case NC_ENC_SET_NIP44_NONCE:

		/* Nonce buffer must be at least the size, max doesnt matter */
		CHECK_ARG_RANGE(valueLen, NC_ENCRYPTION_NONCE_SIZE, UINT32_MAX, 3)

		/* Nonce is only used in nip44 mode */
		ENSURE_ENC_MODE(args, NC_ENC_VERSION_NIP44)

		args->nonceData = value;

		return NC_SUCCESS;

	case NC_ENC_SET_NIP44_MAC_KEY:

		/* The maximum size of the buffer doesn't matter as long as its larger than the key size */
		CHECK_ARG_RANGE(valueLen, NC_HMAC_KEY_SIZE, UINT32_MAX, 3)

		/* Mac key is only used in nip44 mode */
		ENSURE_ENC_MODE(args, NC_ENC_VERSION_NIP44)

		/*
		* During encryption the key data buffer is used
		* to write the hmac hey used for MAC computation
		* operations.
		*/
		args->keyData = value;

		return NC_SUCCESS;
	}

	return E_INVALID_ARG;
}

NC_EXPORT NCResult NCSetEncryptionProperty(
	NCEncryptionArgs* args,
	uint32_t property,
	uint32_t value
)
{
	return NCSetEncryptionPropertyEx(
		args, 
		property, 
		(uint8_t*)&value, 
		sizeof(uint32_t)
	);
}

NC_EXPORT NCResult NCSetEncryptionData(
	NCEncryptionArgs* args,
	const uint8_t* input,
	uint8_t* output,
	uint32_t dataSize
)
{
	CHECK_NULL_ARG(args, 0)
	CHECK_NULL_ARG(input, 1)
	CHECK_NULL_ARG(output, 2)
	CHECK_ARG_RANGE(dataSize, NIP44_MIN_ENC_MESSAGE_SIZE, NIP44_MAX_ENC_MESSAGE_SIZE, 3)

	args->inputData = input;
	args->outputData = output;
	args->dataSize = dataSize;

	return NC_SUCCESS;	
}