summaryrefslogtreecommitdiff
path: root/src/openvpn/cryptoapi.c
blob: 4becef4d1d01c42837d153970a3b36ddf83cddc2 (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
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
/*
 * Copyright (c) 2004 Peter 'Luna' Runestig <peter@runestig.com>
 * Copyright (c) 2018 Selva Nair <selva.nair@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifi-
 * cation, are permitted provided that the following conditions are met:
 *
 *   o  Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *
 *   o  Redistributions in binary form must reproduce the above copyright no-
 *      tice, this list of conditions and the following disclaimer in the do-
 *      cumentation and/or other materials provided with the distribution.
 *
 *   o  The names of the contributors may not be used to endorse or promote
 *      products derived from this software without specific prior written
 *      permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LI-
 * ABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUEN-
 * TIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEV-
 * ER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABI-
 * LITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif

#include "syshead.h"

#ifdef ENABLE_CRYPTOAPI

#include <openssl/ssl.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include <windows.h>
#include <wincrypt.h>
#include <ncrypt.h>
#include <stdio.h>
#include <ctype.h>
#include <assert.h>

#include "buffer.h"
#include "openssl_compat.h"
#include "win32.h"

/* MinGW w32api 3.17 is still incomplete when it comes to CryptoAPI while
 * MinGW32-w64 defines all macros used. This is a hack around that problem.
 */
#ifndef CERT_SYSTEM_STORE_LOCATION_SHIFT
#define CERT_SYSTEM_STORE_LOCATION_SHIFT 16
#endif
#ifndef CERT_SYSTEM_STORE_CURRENT_USER_ID
#define CERT_SYSTEM_STORE_CURRENT_USER_ID 1
#endif
#ifndef CERT_SYSTEM_STORE_CURRENT_USER
#define CERT_SYSTEM_STORE_CURRENT_USER (CERT_SYSTEM_STORE_CURRENT_USER_ID << CERT_SYSTEM_STORE_LOCATION_SHIFT)
#endif
#ifndef CERT_STORE_READONLY_FLAG
#define CERT_STORE_READONLY_FLAG 0x00008000
#endif
#ifndef CERT_STORE_OPEN_EXISTING_FLAG
#define CERT_STORE_OPEN_EXISTING_FLAG 0x00004000
#endif

/* Size of an SSL signature: MD5+SHA1 */
#define SSL_SIG_LENGTH  36

/* try to funnel any Windows/CryptoAPI error messages to OpenSSL ERR_... */
#define ERR_LIB_CRYPTOAPI (ERR_LIB_USER + 69)   /* 69 is just a number... */
#define CRYPTOAPIerr(f)   err_put_ms_error(GetLastError(), (f), __FILE__, __LINE__)
#define CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE                  100
#define CRYPTOAPI_F_CERT_FIND_CERTIFICATE_IN_STORE          101
#define CRYPTOAPI_F_CRYPT_ACQUIRE_CERTIFICATE_PRIVATE_KEY   102
#define CRYPTOAPI_F_CRYPT_CREATE_HASH                       103
#define CRYPTOAPI_F_CRYPT_GET_HASH_PARAM                    104
#define CRYPTOAPI_F_CRYPT_SET_HASH_PARAM                    105
#define CRYPTOAPI_F_CRYPT_SIGN_HASH                         106
#define CRYPTOAPI_F_LOAD_LIBRARY                            107
#define CRYPTOAPI_F_GET_PROC_ADDRESS                        108
#define CRYPTOAPI_F_NCRYPT_SIGN_HASH                        109

static ERR_STRING_DATA CRYPTOAPI_str_functs[] = {
    { ERR_PACK(ERR_LIB_CRYPTOAPI, 0, 0),                                    "microsoft cryptoapi"},
    { ERR_PACK(0, CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE, 0),                   "CertOpenSystemStore" },
    { ERR_PACK(0, CRYPTOAPI_F_CERT_FIND_CERTIFICATE_IN_STORE, 0),           "CertFindCertificateInStore" },
    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_ACQUIRE_CERTIFICATE_PRIVATE_KEY, 0),    "CryptAcquireCertificatePrivateKey" },
    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_CREATE_HASH, 0),                        "CryptCreateHash" },
    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_GET_HASH_PARAM, 0),                     "CryptGetHashParam" },
    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_SET_HASH_PARAM, 0),                     "CryptSetHashParam" },
    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_SIGN_HASH, 0),                          "CryptSignHash" },
    { ERR_PACK(0, CRYPTOAPI_F_LOAD_LIBRARY, 0),                             "LoadLibrary" },
    { ERR_PACK(0, CRYPTOAPI_F_GET_PROC_ADDRESS, 0),                         "GetProcAddress" },
    { ERR_PACK(0, CRYPTOAPI_F_NCRYPT_SIGN_HASH, 0),                         "NCryptSignHash" },
    { 0, NULL }
};

/* index for storing external data in EC_KEY: < 0 means uninitialized */
static int ec_data_idx = -1;

/* Global EVP_PKEY_METHOD used to override the sign operation */
static EVP_PKEY_METHOD *pmethod;
static int (*default_pkey_sign_init) (EVP_PKEY_CTX *ctx);
static int (*default_pkey_sign) (EVP_PKEY_CTX *ctx, unsigned char *sig,
                                 size_t *siglen, const unsigned char *tbs, size_t tbslen);

typedef struct _CAPI_DATA {
    const CERT_CONTEXT *cert_context;
    HCRYPTPROV_OR_NCRYPT_KEY_HANDLE crypt_prov;
    DWORD key_spec;
    BOOL free_crypt_prov;
    int ref_count;
} CAPI_DATA;

/* Translate OpenSSL padding type to CNG padding type
 * Returns 0 for unknown/unsupported padding.
 */
static DWORD
cng_padding_type(int padding)
{
    DWORD pad = 0;

    switch (padding)
    {
        case RSA_NO_PADDING:
            break;

        case RSA_PKCS1_PADDING:
            pad = BCRYPT_PAD_PKCS1;
            break;

        case RSA_PKCS1_PSS_PADDING:
            pad = BCRYPT_PAD_PSS;
            break;

        default:
            msg(M_WARN|M_INFO, "cryptoapicert: unknown OpenSSL padding type %d.",
                padding);
    }

    return pad;
}

/*
 * Translate OpenSSL hash OID to CNG algorithm name. Returns
 * "UNKNOWN" for unsupported algorithms and NULL for MD5+SHA1
 * mixed hash used in TLS 1.1 and earlier.
 */
static const wchar_t *
cng_hash_algo(int md_type)
{
    const wchar_t *alg = L"UNKNOWN";
    switch (md_type)
    {
        case NID_md5:
            alg = BCRYPT_MD5_ALGORITHM;
            break;

        case NID_sha1:
            alg = BCRYPT_SHA1_ALGORITHM;
            break;

        case NID_sha256:
            alg = BCRYPT_SHA256_ALGORITHM;
            break;

        case NID_sha384:
            alg = BCRYPT_SHA384_ALGORITHM;
            break;

        case NID_sha512:
            alg = BCRYPT_SHA512_ALGORITHM;
            break;

        case NID_md5_sha1:
        case 0:
            alg = NULL;
            break;

        default:
            msg(M_WARN|M_INFO, "cryptoapicert: Unknown hash type NID=0x%x", md_type);
            break;
    }
    return alg;
}

static void
CAPI_DATA_free(CAPI_DATA *cd)
{
    if (!cd || cd->ref_count-- > 0)
    {
        return;
    }
    if (cd->free_crypt_prov && cd->crypt_prov)
    {
        if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
        {
            NCryptFreeObject(cd->crypt_prov);
        }
        else
        {
            CryptReleaseContext(cd->crypt_prov, 0);
        }
    }
    if (cd->cert_context)
    {
        CertFreeCertificateContext(cd->cert_context);
    }
    free(cd);
}

static char *
ms_error_text(DWORD ms_err)
{
    LPVOID lpMsgBuf = NULL;
    char *rv = NULL;

    FormatMessage(
        FORMAT_MESSAGE_ALLOCATE_BUFFER
        |FORMAT_MESSAGE_FROM_SYSTEM
        |FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL, ms_err,
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), /* Default language */
        (LPTSTR) &lpMsgBuf, 0, NULL);
    if (lpMsgBuf)
    {
        char *p;
        rv = string_alloc(lpMsgBuf, NULL);
        LocalFree(lpMsgBuf);
        /* trim to the left */
        if (rv)
        {
            for (p = rv + strlen(rv) - 1; p >= rv; p--)
            {
                if (isspace(*p))
                {
                    *p = '\0';
                }
                else
                {
                    break;
                }
            }
        }
    }
    return rv;
}

static void
err_put_ms_error(DWORD ms_err, int func, const char *file, int line)
{
    static int init = 0;
#define ERR_MAP_SZ 16
    static struct {
        int err;
        DWORD ms_err;       /* I don't think we get more than 16 *different* errors */
    } err_map[ERR_MAP_SZ];  /* in here, before we give up the whole thing...        */
    int i;

    if (ms_err == 0)
    {
        /* 0 is not an error */
        return;
    }
    if (!init)
    {
        ERR_load_strings(ERR_LIB_CRYPTOAPI, CRYPTOAPI_str_functs);
        memset(&err_map, 0, sizeof(err_map));
        init++;
    }
    /* since MS error codes are 32 bit, and the ones in the ERR_... system is
     * only 12, we must have a mapping table between them.  */
    for (i = 0; i < ERR_MAP_SZ; i++)
    {
        if (err_map[i].ms_err == ms_err)
        {
            ERR_PUT_error(ERR_LIB_CRYPTOAPI, func, err_map[i].err, file, line);
            break;
        }
        else if (err_map[i].ms_err == 0)
        {
            /* end of table, add new entry */
            ERR_STRING_DATA *esd = calloc(2, sizeof(*esd));
            if (esd == NULL)
            {
                break;
            }
            err_map[i].ms_err = ms_err;
            err_map[i].err = esd->error = i + 100;
            esd->string = ms_error_text(ms_err);
            check_malloc_return(esd->string);
            ERR_load_strings(ERR_LIB_CRYPTOAPI, esd);
            ERR_PUT_error(ERR_LIB_CRYPTOAPI, func, err_map[i].err, file, line);
            break;
        }
    }
}

/* encrypt */
static int
rsa_pub_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
{
    /* I haven't been able to trigger this one, but I want to know if it happens... */
    assert(0);

    return 0;
}

/* verify arbitrary data */
static int
rsa_pub_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
{
    /* I haven't been able to trigger this one, but I want to know if it happens... */
    assert(0);

    return 0;
}

/**
 * Sign the hash in 'from' using NCryptSignHash(). This requires an NCRYPT
 * key handle in cd->crypt_prov. On return the signature is in 'to'. Returns
 * the length of the signature or 0 on error.
 * This is used only for RSA and padding should be BCRYPT_PAD_PKCS1 or
 * BCRYPT_PAD_PSS.
 * If the hash_algo is not NULL, PKCS #1 DigestInfo header gets added
 * to |from|, else it is signed as is. Use NULL for MD5 + SHA1 hash used
 * in TLS 1.1 and earlier.
 * In case of PSS padding, |saltlen| should specify the size of salt to use.
 * If |to| is NULL returns the required buffer size.
 */
static int
priv_enc_CNG(const CAPI_DATA *cd, const wchar_t *hash_algo, const unsigned char *from,
             int flen, unsigned char *to, int tlen, DWORD padding, DWORD saltlen)
{
    NCRYPT_KEY_HANDLE hkey = cd->crypt_prov;
    DWORD len = 0;
    ASSERT(cd->key_spec == CERT_NCRYPT_KEY_SPEC);

    DWORD status;

    msg(D_LOW, "Signing hash using CNG: data size = %d padding = %lu", flen, padding);

    if (padding == BCRYPT_PAD_PKCS1)
    {
        BCRYPT_PKCS1_PADDING_INFO padinfo = {hash_algo};
        status = NCryptSignHash(hkey, &padinfo, (BYTE *)from, flen,
                                to, tlen, &len, padding);
    }
    else if (padding == BCRYPT_PAD_PSS)
    {
        BCRYPT_PSS_PADDING_INFO padinfo = {hash_algo, saltlen};
        status = NCryptSignHash(hkey, &padinfo, (BYTE *)from, flen,
                                to, tlen, &len, padding);
    }
    else
    {
        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
        return 0;
    }

    if (status != ERROR_SUCCESS)
    {
        SetLastError(status);
        CRYPTOAPIerr(CRYPTOAPI_F_NCRYPT_SIGN_HASH);
        len = 0;
    }

    /* Unlike CAPI, CNG signature is in big endian order. No reversing needed. */
    return len;
}

/* sign arbitrary data */
static int
rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
{
    CAPI_DATA *cd = (CAPI_DATA *) RSA_meth_get0_app_data(RSA_get_method(rsa));
    HCRYPTHASH hash;
    DWORD hash_size, len, i;
    unsigned char *buf;

    if (cd == NULL)
    {
        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_PASSED_NULL_PARAMETER);
        return 0;
    }

    if (padding != RSA_PKCS1_PADDING)
    {
        /* AFAICS, CryptSignHash() *always* uses PKCS1 padding. */
        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
        return 0;
    }

    if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
    {
        return priv_enc_CNG(cd, NULL, from, flen, to, RSA_size(rsa),
                            cng_padding_type(padding), 0);
    }

    /* Unfortunately, there is no "CryptSign()" function in CryptoAPI, that would
     * be way to straightforward for M$, I guess... So we have to do it this
     * tricky way instead, by creating a "Hash", and load the already-made hash
     * from 'from' into it.  */
    /* For now, we only support NID_md5_sha1 */
    if (flen != SSL_SIG_LENGTH)
    {
        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_INVALID_MESSAGE_LENGTH);
        return 0;
    }
    if (!CryptCreateHash(cd->crypt_prov, CALG_SSL3_SHAMD5, 0, 0, &hash))
    {
        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_CREATE_HASH);
        return 0;
    }
    len = sizeof(hash_size);
    if (!CryptGetHashParam(hash, HP_HASHSIZE, (BYTE *) &hash_size, &len, 0))
    {
        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_GET_HASH_PARAM);
        CryptDestroyHash(hash);
        return 0;
    }
    if ((int) hash_size != flen)
    {
        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_INVALID_MESSAGE_LENGTH);
        CryptDestroyHash(hash);
        return 0;
    }
    if (!CryptSetHashParam(hash, HP_HASHVAL, (BYTE * ) from, 0))
    {
        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_SET_HASH_PARAM);
        CryptDestroyHash(hash);
        return 0;
    }

    len = RSA_size(rsa);
    buf = malloc(len);
    if (buf == NULL)
    {
        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
        CryptDestroyHash(hash);
        return 0;
    }
    if (!CryptSignHash(hash, cd->key_spec, NULL, 0, buf, &len))
    {
        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_SIGN_HASH);
        CryptDestroyHash(hash);
        free(buf);
        return 0;
    }
    /* and now, we have to reverse the byte-order in the result from CryptSignHash()... */
    for (i = 0; i < len; i++)
    {
        to[i] = buf[len - i - 1];
    }
    free(buf);

    CryptDestroyHash(hash);
    return len;
}

/**
 * Sign the hash in |m| and return the signature in |sig|.
 * Returns 1 on success, 0 on error.
 * NCryptSignHash() is used to sign and it is instructed to add the
 * the PKCS #1 DigestInfo header to |m| unless the hash algorithm is
 * the MD5/SHA1 combination used in TLS 1.1 and earlier versions.
 * OpenSSL exercises this callback only when padding is PKCS1 v1.5.
 */
static int
rsa_sign_CNG(int type, const unsigned char *m, unsigned int m_len,
             unsigned char *sig, unsigned int *siglen, const RSA *rsa)
{
    CAPI_DATA *cd = (CAPI_DATA *) RSA_meth_get0_app_data(RSA_get_method(rsa));
    const wchar_t *alg = NULL;
    int padding = RSA_PKCS1_PADDING;

    *siglen = 0;
    if (cd == NULL)
    {
        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_PASSED_NULL_PARAMETER);
        return 0;
    }

    alg = cng_hash_algo(type);
    if (alg && wcscmp(alg, L"UNKNOWN") == 0)
    {
        RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
        return 0;
    }

    *siglen = priv_enc_CNG(cd, alg, m, (int)m_len, sig, RSA_size(rsa),
                           cng_padding_type(padding), 0);

    return (*siglen == 0) ? 0 : 1;
}

/* decrypt */
static int
rsa_priv_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
{
    /* I haven't been able to trigger this one, but I want to know if it happens... */
    assert(0);

    return 0;
}

/* called at RSA_new */
static int
init(RSA *rsa)
{

    return 0;
}

/* called at RSA_free */
static int
finish(RSA *rsa)
{
    const RSA_METHOD *rsa_meth = RSA_get_method(rsa);
    CAPI_DATA *cd = (CAPI_DATA *) RSA_meth_get0_app_data(rsa_meth);

    if (cd == NULL)
    {
        return 0;
    }
    CAPI_DATA_free(cd);
    RSA_meth_free((RSA_METHOD *) rsa_meth);
    return 1;
}

#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)

static EC_KEY_METHOD *ec_method = NULL;

/** EC_KEY_METHOD callback: called when the key is freed */
static void
ec_finish(EC_KEY *ec)
{
    EC_KEY_METHOD_free(ec_method);
    ec_method = NULL;
    CAPI_DATA *cd = EC_KEY_get_ex_data(ec, ec_data_idx);
    CAPI_DATA_free(cd);
    EC_KEY_set_ex_data(ec, ec_data_idx, NULL);
}

/** EC_KEY_METHOD callback sign_setup(): we do nothing here */
static int
ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
{
    return 1;
}

/**
 * Helper to convert ECDSA signature returned by NCryptSignHash
 * to an ECDSA_SIG structure.
 * On entry 'buf[]' of length len contains r and s concatenated.
 * Returns a newly allocated ECDSA_SIG or NULL (on error).
 */
static ECDSA_SIG *
ecdsa_bin2sig(unsigned char *buf, int len)
{
    ECDSA_SIG *ecsig = NULL;
    DWORD rlen = len/2;
    BIGNUM *r = BN_bin2bn(buf, rlen, NULL);
    BIGNUM *s = BN_bin2bn(buf+rlen, rlen, NULL);
    if (!r || !s)
    {
        goto err;
    }
    ecsig = ECDSA_SIG_new(); /* in openssl 1.1 this does not allocate r, s */
    if (!ecsig)
    {
        goto err;
    }
    if (!ECDSA_SIG_set0(ecsig, r, s)) /* ecsig takes ownership of r and s */
    {
        ECDSA_SIG_free(ecsig);
        goto err;
    }
    return ecsig;
err:
    BN_free(r); /* it is ok to free NULL BN */
    BN_free(s);
    return NULL;
}

/** EC_KEY_METHOD callback sign_sig(): sign and return an ECDSA_SIG pointer. */
static ECDSA_SIG *
ecdsa_sign_sig(const unsigned char *dgst, int dgstlen,
               const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *ec)
{
    ECDSA_SIG *ecsig = NULL;
    CAPI_DATA *cd = (CAPI_DATA *)EC_KEY_get_ex_data(ec, ec_data_idx);

    ASSERT(cd->key_spec == CERT_NCRYPT_KEY_SPEC);

    NCRYPT_KEY_HANDLE hkey = cd->crypt_prov;
    BYTE buf[512]; /* large enough buffer for signature to avoid malloc */
    DWORD len = _countof(buf);

    msg(D_LOW, "Cryptoapi: signing hash using EC key: data size = %d", dgstlen);

    DWORD status = NCryptSignHash(hkey, NULL, (BYTE *)dgst, dgstlen, (BYTE *)buf, len, &len, 0);
    if (status != ERROR_SUCCESS)
    {
        SetLastError(status);
        CRYPTOAPIerr(CRYPTOAPI_F_NCRYPT_SIGN_HASH);
    }
    else
    {
        /* NCryptSignHash returns r, s concatenated in buf[] */
        ecsig = ecdsa_bin2sig(buf, len);
    }
    return ecsig;
}

/** EC_KEY_METHOD callback sign(): sign and return a DER encoded signature */
static int
ecdsa_sign(int type, const unsigned char *dgst, int dgstlen, unsigned char *sig,
           unsigned int *siglen, const BIGNUM *kinv, const BIGNUM *r, EC_KEY *ec)
{
    ECDSA_SIG *s;

    *siglen = 0;
    s = ecdsa_sign_sig(dgst, dgstlen, NULL, NULL, ec);
    if (s == NULL)
    {
        return 0;
    }

    /* convert internal signature structure 's' to DER encoded byte array in sig */
    int len = i2d_ECDSA_SIG(s, NULL);
    if (len > ECDSA_size(ec))
    {
        ECDSA_SIG_free(s);
        msg(M_NONFATAL,"Error: DER encoded ECDSA signature is too long (%d bytes)", len);
        return 0;
    }
    *siglen = i2d_ECDSA_SIG(s, &sig);
    ECDSA_SIG_free(s);

    return 1;
}

static int
ssl_ctx_set_eckey(SSL_CTX *ssl_ctx, CAPI_DATA *cd, EVP_PKEY *pkey)
{
    EC_KEY *ec = NULL;
    EVP_PKEY *privkey = NULL;

    if (cd->key_spec != CERT_NCRYPT_KEY_SPEC)
    {
        msg(M_NONFATAL, "ERROR: cryptoapicert with only legacy private key handle available."
            " EC certificate not supported.");
        goto err;
    }
    /* create a method struct with default callbacks filled in */
    ec_method = EC_KEY_METHOD_new(EC_KEY_OpenSSL());
    if (!ec_method)
    {
        goto err;
    }

    /* We only need to set finish among init methods, and sign methods */
    EC_KEY_METHOD_set_init(ec_method, NULL, ec_finish, NULL, NULL, NULL, NULL);
    EC_KEY_METHOD_set_sign(ec_method, ecdsa_sign, ecdsa_sign_setup, ecdsa_sign_sig);

    ec = EC_KEY_dup(EVP_PKEY_get0_EC_KEY(pkey));
    if (!ec)
    {
        goto err;
    }
    if (!EC_KEY_set_method(ec, ec_method))
    {
        goto err;
    }

    /* get an index to store cd as external data */
    if (ec_data_idx < 0)
    {
        ec_data_idx = EC_KEY_get_ex_new_index(0, "cryptapicert ec key", NULL, NULL, NULL);
        if (ec_data_idx < 0)
        {
            goto err;
        }
    }
    EC_KEY_set_ex_data(ec, ec_data_idx, cd);

    /* cd assigned to ec as ex_data, increase its refcount */
    cd->ref_count++;

    privkey = EVP_PKEY_new();
    if (!EVP_PKEY_assign_EC_KEY(privkey, ec))
    {
        EC_KEY_free(ec);
        goto err;
    }
    /* from here on ec will get freed with privkey */

    if (!SSL_CTX_use_PrivateKey(ssl_ctx, privkey))
    {
        goto err;
    }
    EVP_PKEY_free(privkey); /* this will dn_ref or free ec as well */
    return 1;

err:
    if (privkey)
    {
        EVP_PKEY_free(privkey);
    }
    else if (ec)
    {
        EC_KEY_free(ec);
    }
    if (ec_method) /* do always set ec_method = NULL after freeing it */
    {
        EC_KEY_METHOD_free(ec_method);
        ec_method = NULL;
    }
    return 0;
}

#endif /* OPENSSL_VERSION_NUMBER >= 1.1.0 */

static const CERT_CONTEXT *
find_certificate_in_store(const char *cert_prop, HCERTSTORE cert_store)
{
    /* Find, and use, the desired certificate from the store. The
     * 'cert_prop' certificate search string can look like this:
     * SUBJ:<certificate substring to match>
     * THUMB:<certificate thumbprint hex value>, e.g.
     *     THUMB:f6 49 24 41 01 b4 fb 44 0c ce f4 36 ae d0 c4 c9 df 7a b6 28
     * The first matching certificate that has not expired is returned.
     */
    const CERT_CONTEXT *rv = NULL;
    DWORD find_type;
    const void *find_param;
    unsigned char hash[255];
    CRYPT_HASH_BLOB blob = {.cbData = 0, .pbData = hash};
    struct gc_arena gc = gc_new();

    if (!strncmp(cert_prop, "SUBJ:", 5))
    {
        /* skip the tag */
        find_param = wide_string(cert_prop + 5, &gc);
        find_type = CERT_FIND_SUBJECT_STR_W;
    }
    else if (!strncmp(cert_prop, "THUMB:", 6))
    {
        const char *p;
        int i, x = 0;
        find_type = CERT_FIND_HASH;
        find_param = &blob;

        /* skip the tag */
        cert_prop += 6;
        for (p = cert_prop, i = 0; *p && i < sizeof(hash); i++)
        {
            if (*p >= '0' && *p <= '9')
            {
                x = (*p - '0') << 4;
            }
            else if (*p >= 'A' && *p <= 'F')
            {
                x = (*p - 'A' + 10) << 4;
            }
            else if (*p >= 'a' && *p <= 'f')
            {
                x = (*p - 'a' + 10) << 4;
            }
            if (!*++p)  /* unexpected end of string */
            {
                msg(M_WARN, "WARNING: cryptoapicert: error parsing <THUMB:%s>.", cert_prop);
                goto out;
            }
            if (*p >= '0' && *p <= '9')
            {
                x += *p - '0';
            }
            else if (*p >= 'A' && *p <= 'F')
            {
                x += *p - 'A' + 10;
            }
            else if (*p >= 'a' && *p <= 'f')
            {
                x += *p - 'a' + 10;
            }
            hash[i] = x;
            /* skip any space(s) between hex numbers */
            for (p++; *p && *p == ' '; p++)
            {
            }
        }
        blob.cbData = i;
    }
    else
    {
        msg(M_WARN, "WARNING: cryptoapicert: unsupported certificate specification <%s>", cert_prop);
        goto out;
    }

    while (true)
    {
        int validity = 1;
        /* this frees previous rv, if not NULL */
        rv = CertFindCertificateInStore(cert_store, X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
                                        0, find_type, find_param, rv);
        if (rv)
        {
            validity = CertVerifyTimeValidity(NULL, rv->pCertInfo);
        }
        if (!rv || validity == 0)
        {
            break;
        }
        msg(M_WARN, "WARNING: cryptoapicert: ignoring certificate in store %s.",
            validity < 0 ? "not yet valid" : "that has expired");
    }

out:
    gc_free(&gc);
    return rv;
}

#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)

static const CAPI_DATA *
retrieve_capi_data(EVP_PKEY *pkey)
{
    const CAPI_DATA *cd = NULL;

    if (pkey && EVP_PKEY_id(pkey) == EVP_PKEY_RSA)
    {
        RSA *rsa = EVP_PKEY_get0_RSA(pkey);
        if (rsa)
        {
            cd = (CAPI_DATA *)RSA_meth_get0_app_data(RSA_get_method(rsa));
        }
    }
    return cd;
}

static int
pkey_rsa_sign_init(EVP_PKEY_CTX *ctx)
{
    msg(D_LOW, "cryptoapicert: enter pkey_rsa_sign_init");

    EVP_PKEY *pkey = EVP_PKEY_CTX_get0_pkey(ctx);

    if (pkey && retrieve_capi_data(pkey))
    {
        return 1; /* Return success */
    }
    else if (default_pkey_sign_init)  /* Not our key. Call the default method */
    {
        return default_pkey_sign_init(ctx);
    }
    return 1;
}

/**
 * Implementation of EVP_PKEY_sign() using CNG: sign the digest in |tbs|
 * and save the the signature in |sig| and its size in |*siglen|.
 * If |sig| is NULL the required buffer size is returned in |*siglen|.
 * Returns value is 1 on success, 0 or a negative integer on error.
 */
static int
pkey_rsa_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
              const unsigned char *tbs, size_t tbslen)
{
    EVP_PKEY *pkey = NULL;
    const CAPI_DATA *cd = NULL;
    EVP_MD *md = NULL;
    const wchar_t *alg = NULL;

    int padding = 0;
    int hashlen = 0;
    int saltlen = 0;

    pkey = EVP_PKEY_CTX_get0_pkey(ctx);
    if (pkey)
    {
        cd = retrieve_capi_data(pkey);
    }

    /*
     * We intercept all sign requests, not just the one's for our key.
     * Check the key and call the saved OpenSSL method for unknown keys.
     */
    if (!pkey || !cd)
    {
        if (default_pkey_sign)
        {
            return default_pkey_sign(ctx, sig, siglen, tbs, tbslen);
        }
        else  /* This should not happen */
        {
            msg(M_FATAL, "cryptopaicert: Unknown key and no default sign operation to fallback on");
            return -1;
        }
    }

    if (!EVP_PKEY_CTX_get_rsa_padding(ctx, &padding))
    {
        padding = RSA_PKCS1_PADDING; /* Default padding for RSA */
    }

    if (EVP_PKEY_CTX_get_signature_md(ctx, &md))
    {
        hashlen = EVP_MD_size(md);
        alg = cng_hash_algo(EVP_MD_type(md));

        /*
         * alg == NULL indicates legacy MD5+SHA1 hash, else alg should be a valid
         * digest algorithm.
         */
        if (alg && wcscmp(alg, L"UNKNOWN") == 0)
        {
            RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
            return -1;
        }
    }
    else
    {
        msg(M_NONFATAL, "cryptoapicert: could not determine the signature digest algorithm");
        RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
        return -1;
    }

    if (tbslen != (size_t)hashlen)
    {
        RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_INVALID_DIGEST_LENGTH);
        return -1;
    }

    /* If padding is PSS, determine parameters to pass to CNG */
    if (padding == RSA_PKCS1_PSS_PADDING)
    {
        /*
         * Ensure the digest type for signature and mask generation match.
         * In CNG there is no option to specify separate hash functions for
         * the two, but OpenSSL supports it. However, I have not seen the
         * two being different in practice. Also the recommended practice is
         * to use the same for both (rfc 8017 sec 8.1).
         */
        EVP_MD *mgf1md;
        if (!EVP_PKEY_CTX_get_rsa_mgf1_md(ctx, &mgf1md)
            || EVP_MD_type(mgf1md) != EVP_MD_type(md))
        {
            msg(M_NONFATAL, "cryptoapicert: Unknown MGF1 digest type or does"
                " not match the signature digest type.");
            RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNSUPPORTED_MASK_PARAMETER);
        }

        if (!EVP_PKEY_CTX_get_rsa_pss_saltlen(ctx, &saltlen))
        {
            msg(M_WARN, "cryptoapicert: unable to get the salt length from context."
                " Using the default value.");
            saltlen = -1;
        }

        /*
         * In OpenSSL saltlen = -1 indicates to use the size of the digest as
         * size of the salt. A value of -2 or -3 indicates maximum salt length
         * that will fit. See RSA_padding_add_PKCS1_PSS_mgf1() of OpenSSL.
         */
        if (saltlen == -1)
        {
            saltlen = hashlen;
        }
        else if (saltlen < 0)
        {
            const RSA *rsa = EVP_PKEY_get0_RSA(pkey);
            saltlen = RSA_size(rsa) - hashlen - 2; /* max salt length for RSASSA-PSS */
            if (RSA_bits(rsa) &0x7) /* number of bits in the key not a multiple of 8 */
            {
                saltlen--;
            }
        }

        if (saltlen < 0)
        {
            RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
            return -1;
        }
        msg(D_LOW, "cryptoapicert: PSS padding using saltlen = %d", saltlen);
    }

    msg(D_LOW, "cryptoapicert: calling priv_enc_CNG with alg = %ls", alg);
    *siglen = priv_enc_CNG(cd, alg, tbs, (int)tbslen, sig, *siglen,
                           cng_padding_type(padding), (DWORD)saltlen);

    return (*siglen == 0) ? 0 : 1;
}

#endif /* OPENSSL_VERSION >= 1.1.0 */

static int
ssl_ctx_set_rsakey(SSL_CTX *ssl_ctx, CAPI_DATA *cd, EVP_PKEY *pkey)
{
    RSA *rsa = NULL, *pub_rsa;
    RSA_METHOD *my_rsa_method = NULL;
    bool rsa_method_set = false;

    my_rsa_method = RSA_meth_new("Microsoft Cryptography API RSA Method",
                                 RSA_METHOD_FLAG_NO_CHECK);
    check_malloc_return(my_rsa_method);
    RSA_meth_set_pub_enc(my_rsa_method, rsa_pub_enc);
    RSA_meth_set_pub_dec(my_rsa_method, rsa_pub_dec);
    RSA_meth_set_priv_enc(my_rsa_method, rsa_priv_enc);
    RSA_meth_set_priv_dec(my_rsa_method, rsa_priv_dec);
    RSA_meth_set_init(my_rsa_method, NULL);
    RSA_meth_set_finish(my_rsa_method, finish);
    RSA_meth_set0_app_data(my_rsa_method, cd);

    /*
     * For CNG, set the RSA_sign method which gets priority over priv_enc().
     * This method is called with the raw hash without the digestinfo
     * header and works better when using NCryptSignHash() with some tokens.
     * However, if PSS padding is in use, openssl does not call this
     * function but adds the padding and then calls rsa_priv_enc()
     * with padding set to NONE which is not supported by CNG.
     * So, when posisble (OpenSSL 1.1.0 and up), we hook on to the sign
     * operation in EVP_PKEY_METHOD struct.
     */
    if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
    {
#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
        RSA_meth_set_sign(my_rsa_method, rsa_sign_CNG);
#else
        /* pmethod is global -- initialize only if NULL */
        if (!pmethod)
        {
            pmethod = EVP_PKEY_meth_new(EVP_PKEY_RSA, 0);
            if (!pmethod)
            {
                SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_MALLOC_FAILURE);
                goto err;
            }
            const EVP_PKEY_METHOD *default_pmethod = EVP_PKEY_meth_find(EVP_PKEY_RSA);
            EVP_PKEY_meth_copy(pmethod, default_pmethod);

            /* We want to override only sign_init() and sign() */
            EVP_PKEY_meth_set_sign(pmethod, pkey_rsa_sign_init, pkey_rsa_sign);
            EVP_PKEY_meth_add0(pmethod);

            /* Keep a copy of the default sign and sign_init methods */

#if (OPENSSL_VERSION_NUMBER < 0x1010009fL)   /* > version 1.1.0i */
            /* The function signature is not const-correct in these versions */
            EVP_PKEY_meth_get_sign((EVP_PKEY_METHOD *)default_pmethod, &default_pkey_sign_init,
                                   &default_pkey_sign);
#else
            EVP_PKEY_meth_get_sign(default_pmethod, &default_pkey_sign_init,
                                   &default_pkey_sign);

#endif
        }
#endif /* (OPENSSL_VERSION_NUMBER < 0x10100000L) */
    }

    rsa = RSA_new();
    if (rsa == NULL)
    {
        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    pub_rsa = EVP_PKEY_get0_RSA(pkey);
    if (!pub_rsa)
    {
        goto err;
    }

    /* Our private key is external, so we fill in only n and e from the public key */
    const BIGNUM *n = NULL;
    const BIGNUM *e = NULL;
    RSA_get0_key(pub_rsa, &n, &e, NULL);
    BIGNUM *rsa_n = BN_dup(n);
    BIGNUM *rsa_e = BN_dup(e);
    if (!rsa_n || !rsa_e || !RSA_set0_key(rsa, rsa_n, rsa_e, NULL))
    {
        BN_free(rsa_n); /* ok to free even if NULL */
        BN_free(rsa_e);
        msg(M_NONFATAL, "ERROR: %s: out of memory", __func__);
        goto err;
    }
    RSA_set_flags(rsa, RSA_flags(rsa) | RSA_FLAG_EXT_PKEY);
    if (!RSA_set_method(rsa, my_rsa_method))
    {
        goto err;
    }
    rsa_method_set = true; /* flag that method pointer will get freed with the key */
    cd->ref_count++;       /* with method, cd gets assigned to the key as well */

    if (!SSL_CTX_use_RSAPrivateKey(ssl_ctx, rsa))
    {
        goto err;
    }
    /* SSL_CTX_use_RSAPrivateKey() increased the reference count in 'rsa', so
    * we decrease it here with RSA_free(), or it will never be cleaned up. */
    RSA_free(rsa);
    return 1;

err:
    if (rsa)
    {
        RSA_free(rsa);
    }
    if (my_rsa_method && !rsa_method_set)
    {
        RSA_meth_free(my_rsa_method);
    }
    return 0;
}

int
SSL_CTX_use_CryptoAPI_certificate(SSL_CTX *ssl_ctx, const char *cert_prop)
{
    HCERTSTORE cs;
    X509 *cert = NULL;
    CAPI_DATA *cd = calloc(1, sizeof(*cd));

    if (cd == NULL)
    {
        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    /* search CURRENT_USER first, then LOCAL_MACHINE */
    cs = CertOpenStore((LPCSTR) CERT_STORE_PROV_SYSTEM, 0, 0, CERT_SYSTEM_STORE_CURRENT_USER
                       |CERT_STORE_OPEN_EXISTING_FLAG | CERT_STORE_READONLY_FLAG, L"MY");
    if (cs == NULL)
    {
        CRYPTOAPIerr(CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE);
        goto err;
    }
    cd->cert_context = find_certificate_in_store(cert_prop, cs);
    CertCloseStore(cs, 0);
    if (!cd->cert_context)
    {
        cs = CertOpenStore((LPCSTR) CERT_STORE_PROV_SYSTEM, 0, 0, CERT_SYSTEM_STORE_LOCAL_MACHINE
                           |CERT_STORE_OPEN_EXISTING_FLAG | CERT_STORE_READONLY_FLAG, L"MY");
        if (cs == NULL)
        {
            CRYPTOAPIerr(CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE);
            goto err;
        }
        cd->cert_context = find_certificate_in_store(cert_prop, cs);
        CertCloseStore(cs, 0);
        if (cd->cert_context == NULL)
        {
            CRYPTOAPIerr(CRYPTOAPI_F_CERT_FIND_CERTIFICATE_IN_STORE);
            goto err;
        }
    }

    /* cert_context->pbCertEncoded is the cert X509 DER encoded. */
    cert = d2i_X509(NULL, (const unsigned char **) &cd->cert_context->pbCertEncoded,
                    cd->cert_context->cbCertEncoded);
    if (cert == NULL)
    {
        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_ASN1_LIB);
        goto err;
    }

    /* set up stuff to use the private key */
    /* We prefer to get an NCRYPT key handle so that TLS1.2 can be supported */
    DWORD flags = CRYPT_ACQUIRE_COMPARE_KEY_FLAG
                  | CRYPT_ACQUIRE_PREFER_NCRYPT_KEY_FLAG;
    if (!CryptAcquireCertificatePrivateKey(cd->cert_context, flags, NULL,
                                           &cd->crypt_prov, &cd->key_spec, &cd->free_crypt_prov))
    {
        /* if we don't have a smart card reader here, and we try to access a
         * smart card certificate, we get:
         * "Error 1223: The operation was canceled by the user." */
        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_ACQUIRE_CERTIFICATE_PRIVATE_KEY);
        goto err;
    }
    /* here we don't need to do CryptGetUserKey() or anything; all necessary key
     * info is in cd->cert_context, and then, in cd->crypt_prov.  */

    /* if we do not have an NCRYPT key handle restrict TLS to v1.1 or lower */
    int max_version = SSL_CTX_get_max_proto_version(ssl_ctx);
    if ((!max_version || max_version > TLS1_1_VERSION)
        && cd->key_spec != CERT_NCRYPT_KEY_SPEC)
    {
        msg(M_WARN, "WARNING: cryptoapicert: private key is in a legacy store."
            " Restricting TLS version to 1.1");
        if (SSL_CTX_get_min_proto_version(ssl_ctx) > TLS1_1_VERSION)
        {
            msg(M_NONFATAL,
                "ERROR: cryptoapicert: min TLS version larger than 1.1."
                " Try config option --tls-version-min 1.1");
            goto err;
        }
        if (!SSL_CTX_set_max_proto_version(ssl_ctx, TLS1_1_VERSION))
        {
            msg(M_NONFATAL, "ERROR: cryptoapicert: set max TLS version failed");
            goto err;
        }
    }

    /* Public key in cert is NULL until we call SSL_CTX_use_certificate(),
     * so we do it here then...  */
    if (!SSL_CTX_use_certificate(ssl_ctx, cert))
    {
        goto err;
    }

    /* the public key */
    EVP_PKEY *pkey = X509_get0_pubkey(cert);

    /* SSL_CTX_use_certificate() increased the reference count in 'cert', so
     * we decrease it here with X509_free(), or it will never be cleaned up. */
    X509_free(cert);
    cert = NULL;

    if (EVP_PKEY_id(pkey) == EVP_PKEY_RSA)
    {
        if (!ssl_ctx_set_rsakey(ssl_ctx, cd, pkey))
        {
            goto err;
        }
    }
#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
    else if (EVP_PKEY_id(pkey) == EVP_PKEY_EC)
    {
        if (!ssl_ctx_set_eckey(ssl_ctx, cd, pkey))
        {
            goto err;
        }
    }
#endif /* OPENSSL_VERSION_NUMBER >= 1.1.0 */
    else
    {
        msg(M_WARN, "WARNING: cryptoapicert: certificate type not supported");
        goto err;
    }
    CAPI_DATA_free(cd); /* this will do a ref_count-- */
    return 1;

err:
    CAPI_DATA_free(cd);
    return 0;
}

#else  /* ifdef ENABLE_CRYPTOAPI */
#ifdef _MSC_VER  /* Dummy function needed to avoid empty file compiler warning in Microsoft VC */
static void
dummy(void)
{
}
#endif
#endif                          /* _WIN32 */