aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/ts/ts_rsp_verify.c
blob: 086021247c01ca23c3fe3fbba8b72a7a98436bdc (plain) (blame)
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
/*
 * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/objects.h>
#include <openssl/ts.h>
#include <openssl/pkcs7.h>
#include "ts_local.h"

static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
                          X509 *signer, STACK_OF(X509) **chain);
static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
                                  STACK_OF(X509) *chain);
static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si);
static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert);
static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert);
static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
                                    PKCS7 *token, TS_TST_INFO *tst_info);
static int ts_check_status_info(TS_RESP *response);
static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text);
static int ts_check_policy(const ASN1_OBJECT *req_oid,
                           const TS_TST_INFO *tst_info);
static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
                              X509_ALGOR **md_alg,
                              unsigned char **imprint, unsigned *imprint_len);
static int ts_check_imprints(X509_ALGOR *algor_a,
                             const unsigned char *imprint_a, unsigned len_a,
                             TS_TST_INFO *tst_info);
static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info);
static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer);
static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names,
                        GENERAL_NAME *name);
static int ts_find_cert_v2(STACK_OF(ESS_CERT_ID_V2) *cert_ids, X509 *cert);
static ESS_SIGNING_CERT_V2 *ess_get_signing_cert_v2(PKCS7_SIGNER_INFO *si);

/*
 * This must be large enough to hold all values in ts_status_text (with
 * comma separator) or all text fields in ts_failure_info (also with comma).
 */
#define TS_STATUS_BUF_SIZE      256

/*
 * Local mapping between response codes and descriptions.
 */
static const char *ts_status_text[] = {
    "granted",
    "grantedWithMods",
    "rejection",
    "waiting",
    "revocationWarning",
    "revocationNotification"
};

#define TS_STATUS_TEXT_SIZE     OSSL_NELEM(ts_status_text)

static struct {
    int code;
    const char *text;
} ts_failure_info[] = {
    {TS_INFO_BAD_ALG, "badAlg"},
    {TS_INFO_BAD_REQUEST, "badRequest"},
    {TS_INFO_BAD_DATA_FORMAT, "badDataFormat"},
    {TS_INFO_TIME_NOT_AVAILABLE, "timeNotAvailable"},
    {TS_INFO_UNACCEPTED_POLICY, "unacceptedPolicy"},
    {TS_INFO_UNACCEPTED_EXTENSION, "unacceptedExtension"},
    {TS_INFO_ADD_INFO_NOT_AVAILABLE, "addInfoNotAvailable"},
    {TS_INFO_SYSTEM_FAILURE, "systemFailure"}
};


/*-
 * This function carries out the following tasks:
 *      - Checks if there is one and only one signer.
 *      - Search for the signing certificate in 'certs' and in the response.
 *      - Check the extended key usage and key usage fields of the signer
 *      certificate (done by the path validation).
 *      - Build and validate the certificate path.
 *      - Check if the certificate path meets the requirements of the
 *      SigningCertificate ESS signed attribute.
 *      - Verify the signature value.
 *      - Returns the signer certificate in 'signer', if 'signer' is not NULL.
 */
int TS_RESP_verify_signature(PKCS7 *token, STACK_OF(X509) *certs,
                             X509_STORE *store, X509 **signer_out)
{
    STACK_OF(PKCS7_SIGNER_INFO) *sinfos = NULL;
    PKCS7_SIGNER_INFO *si;
    STACK_OF(X509) *signers = NULL;
    X509 *signer;
    STACK_OF(X509) *chain = NULL;
    char buf[4096];
    int i, j = 0, ret = 0;
    BIO *p7bio = NULL;

    /* Some sanity checks first. */
    if (!token) {
        TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_INVALID_NULL_POINTER);
        goto err;
    }
    if (!PKCS7_type_is_signed(token)) {
        TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_WRONG_CONTENT_TYPE);
        goto err;
    }
    sinfos = PKCS7_get_signer_info(token);
    if (!sinfos || sk_PKCS7_SIGNER_INFO_num(sinfos) != 1) {
        TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_THERE_MUST_BE_ONE_SIGNER);
        goto err;
    }
    si = sk_PKCS7_SIGNER_INFO_value(sinfos, 0);
    if (PKCS7_get_detached(token)) {
        TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_NO_CONTENT);
        goto err;
    }

    /*
     * Get hold of the signer certificate, search only internal certificates
     * if it was requested.
     */
    signers = PKCS7_get0_signers(token, certs, 0);
    if (!signers || sk_X509_num(signers) != 1)
        goto err;
    signer = sk_X509_value(signers, 0);

    if (!ts_verify_cert(store, certs, signer, &chain))
        goto err;
    if (!ts_check_signing_certs(si, chain))
        goto err;
    p7bio = PKCS7_dataInit(token, NULL);

    /* We now have to 'read' from p7bio to calculate digests etc. */
    while ((i = BIO_read(p7bio, buf, sizeof(buf))) > 0)
        continue;

    j = PKCS7_signatureVerify(p7bio, token, si, signer);
    if (j <= 0) {
        TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_SIGNATURE_FAILURE);
        goto err;
    }

    if (signer_out) {
        *signer_out = signer;
        X509_up_ref(signer);
    }
    ret = 1;

 err:
    BIO_free_all(p7bio);
    sk_X509_pop_free(chain, X509_free);
    sk_X509_free(signers);

    return ret;
}

/*
 * The certificate chain is returned in chain. Caller is responsible for
 * freeing the vector.
 */
static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
                          X509 *signer, STACK_OF(X509) **chain)
{
    X509_STORE_CTX *cert_ctx = NULL;
    int i;
    int ret = 0;

    *chain = NULL;
    cert_ctx = X509_STORE_CTX_new();
    if (cert_ctx == NULL) {
        TSerr(TS_F_TS_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    if (!X509_STORE_CTX_init(cert_ctx, store, signer, untrusted))
        goto end;
    X509_STORE_CTX_set_purpose(cert_ctx, X509_PURPOSE_TIMESTAMP_SIGN);
    i = X509_verify_cert(cert_ctx);
    if (i <= 0) {
        int j = X509_STORE_CTX_get_error(cert_ctx);
        TSerr(TS_F_TS_VERIFY_CERT, TS_R_CERTIFICATE_VERIFY_ERROR);
        ERR_add_error_data(2, "Verify error:",
                           X509_verify_cert_error_string(j));
        goto err;
    }
    *chain = X509_STORE_CTX_get1_chain(cert_ctx);
    ret = 1;
    goto end;

err:
    ret = 0;

end:
    X509_STORE_CTX_free(cert_ctx);
    return ret;
}

static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
                                  STACK_OF(X509) *chain)
{
    ESS_SIGNING_CERT *ss = ess_get_signing_cert(si);
    STACK_OF(ESS_CERT_ID) *cert_ids = NULL;
    ESS_SIGNING_CERT_V2 *ssv2 = ess_get_signing_cert_v2(si);
    STACK_OF(ESS_CERT_ID_V2) *cert_ids_v2 = NULL;
    X509 *cert;
    int i = 0;
    int ret = 0;

    if (ss != NULL) {
        cert_ids = ss->cert_ids;
        cert = sk_X509_value(chain, 0);
        if (ts_find_cert(cert_ids, cert) != 0)
            goto err;

        /*
         * Check the other certificates of the chain if there are more than one
         * certificate ids in cert_ids.
         */
        if (sk_ESS_CERT_ID_num(cert_ids) > 1) {
            for (i = 1; i < sk_X509_num(chain); ++i) {
                cert = sk_X509_value(chain, i);
                if (ts_find_cert(cert_ids, cert) < 0)
                    goto err;
            }
        }
    } else if (ssv2 != NULL) {
        cert_ids_v2 = ssv2->cert_ids;
        cert = sk_X509_value(chain, 0);
        if (ts_find_cert_v2(cert_ids_v2, cert) != 0)
            goto err;

        /*
         * Check the other certificates of the chain if there are more than one
         * certificate ids in cert_ids.
         */
        if (sk_ESS_CERT_ID_V2_num(cert_ids_v2) > 1) {
            for (i = 1; i < sk_X509_num(chain); ++i) {
                cert = sk_X509_value(chain, i);
                if (ts_find_cert_v2(cert_ids_v2, cert) < 0)
                    goto err;
            }
        }
    } else {
        goto err;
    }

    ret = 1;
 err:
    if (!ret)
        TSerr(TS_F_TS_CHECK_SIGNING_CERTS,
              TS_R_ESS_SIGNING_CERTIFICATE_ERROR);
    ESS_SIGNING_CERT_free(ss);
    ESS_SIGNING_CERT_V2_free(ssv2);
    return ret;
}

static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si)
{
    ASN1_TYPE *attr;
    const unsigned char *p;
    attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificate);
    if (!attr)
        return NULL;
    p = attr->value.sequence->data;
    return d2i_ESS_SIGNING_CERT(NULL, &p, attr->value.sequence->length);
}

static ESS_SIGNING_CERT_V2 *ess_get_signing_cert_v2(PKCS7_SIGNER_INFO *si)
{
    ASN1_TYPE *attr;
    const unsigned char *p;

    attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificateV2);
    if (attr == NULL)
        return NULL;
    p = attr->value.sequence->data;
    return d2i_ESS_SIGNING_CERT_V2(NULL, &p, attr->value.sequence->length);
}

/* Returns < 0 if certificate is not found, certificate index otherwise. */
static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert)
{
    int i;
    unsigned char cert_sha1[SHA_DIGEST_LENGTH];

    if (!cert_ids || !cert)
        return -1;

    X509_digest(cert, EVP_sha1(), cert_sha1, NULL);

    /* Recompute SHA1 hash of certificate if necessary (side effect). */
    X509_check_purpose(cert, -1, 0);

    /* Look for cert in the cert_ids vector. */
    for (i = 0; i < sk_ESS_CERT_ID_num(cert_ids); ++i) {
        ESS_CERT_ID *cid = sk_ESS_CERT_ID_value(cert_ids, i);

        if (cid->hash->length == SHA_DIGEST_LENGTH
            && memcmp(cid->hash->data, cert_sha1, SHA_DIGEST_LENGTH) == 0) {
            ESS_ISSUER_SERIAL *is = cid->issuer_serial;
            if (!is || !ts_issuer_serial_cmp(is, cert))
                return i;
        }
    }

    return -1;
}

/* Returns < 0 if certificate is not found, certificate index otherwise. */
static int ts_find_cert_v2(STACK_OF(ESS_CERT_ID_V2) *cert_ids, X509 *cert)
{
    int i;
    unsigned char cert_digest[EVP_MAX_MD_SIZE];
    unsigned int len;

    /* Look for cert in the cert_ids vector. */
    for (i = 0; i < sk_ESS_CERT_ID_V2_num(cert_ids); ++i) {
        ESS_CERT_ID_V2 *cid = sk_ESS_CERT_ID_V2_value(cert_ids, i);
        const EVP_MD *md;

        if (cid->hash_alg != NULL)
            md = EVP_get_digestbyobj(cid->hash_alg->algorithm);
        else
            md = EVP_sha256();

        X509_digest(cert, md, cert_digest, &len);
        if (cid->hash->length != (int)len)
            return -1;

        if (memcmp(cid->hash->data, cert_digest, cid->hash->length) == 0) {
            ESS_ISSUER_SERIAL *is = cid->issuer_serial;

            if (is == NULL || !ts_issuer_serial_cmp(is, cert))
                return i;
        }
    }

    return -1;
}

static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert)
{
    GENERAL_NAME *issuer;

    if (!is || !cert || sk_GENERAL_NAME_num(is->issuer) != 1)
        return -1;

    issuer = sk_GENERAL_NAME_value(is->issuer, 0);
    if (issuer->type != GEN_DIRNAME
        || X509_NAME_cmp(issuer->d.dirn, X509_get_issuer_name(cert)))
        return -1;

    if (ASN1_INTEGER_cmp(is->serial, X509_get_serialNumber(cert)))
        return -1;

    return 0;
}

/*-
 * Verifies whether 'response' contains a valid response with regards
 * to the settings of the context:
 *      - Gives an error message if the TS_TST_INFO is not present.
 *      - Calls _TS_RESP_verify_token to verify the token content.
 */
int TS_RESP_verify_response(TS_VERIFY_CTX *ctx, TS_RESP *response)
{
    PKCS7 *token = response->token;
    TS_TST_INFO *tst_info = response->tst_info;
    int ret = 0;

    if (!ts_check_status_info(response))
        goto err;
    if (!int_ts_RESP_verify_token(ctx, token, tst_info))
        goto err;
    ret = 1;

 err:
    return ret;
}

/*
 * Tries to extract a TS_TST_INFO structure from the PKCS7 token and
 * calls the internal int_TS_RESP_verify_token function for verifying it.
 */
int TS_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token)
{
    TS_TST_INFO *tst_info = PKCS7_to_TS_TST_INFO(token);
    int ret = 0;
    if (tst_info) {
        ret = int_ts_RESP_verify_token(ctx, token, tst_info);
        TS_TST_INFO_free(tst_info);
    }
    return ret;
}

/*-
 * Verifies whether the 'token' contains a valid time stamp token
 * with regards to the settings of the context. Only those checks are
 * carried out that are specified in the context:
 *      - Verifies the signature of the TS_TST_INFO.
 *      - Checks the version number of the response.
 *      - Check if the requested and returned policies math.
 *      - Check if the message imprints are the same.
 *      - Check if the nonces are the same.
 *      - Check if the TSA name matches the signer.
 *      - Check if the TSA name is the expected TSA.
 */
static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
                                    PKCS7 *token, TS_TST_INFO *tst_info)
{
    X509 *signer = NULL;
    GENERAL_NAME *tsa_name = tst_info->tsa;
    X509_ALGOR *md_alg = NULL;
    unsigned char *imprint = NULL;
    unsigned imprint_len = 0;
    int ret = 0;
    int flags = ctx->flags;

    /* Some options require us to also check the signature */
    if (((flags & TS_VFY_SIGNER) && tsa_name != NULL)
            || (flags & TS_VFY_TSA_NAME)) {
        flags |= TS_VFY_SIGNATURE;
    }

    if ((flags & TS_VFY_SIGNATURE)
        && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer))
        goto err;
    if ((flags & TS_VFY_VERSION)
        && TS_TST_INFO_get_version(tst_info) != 1) {
        TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_UNSUPPORTED_VERSION);
        goto err;
    }
    if ((flags & TS_VFY_POLICY)
        && !ts_check_policy(ctx->policy, tst_info))
        goto err;
    if ((flags & TS_VFY_IMPRINT)
        && !ts_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len,
                              tst_info))
        goto err;
    if ((flags & TS_VFY_DATA)
        && (!ts_compute_imprint(ctx->data, tst_info,
                                &md_alg, &imprint, &imprint_len)
            || !ts_check_imprints(md_alg, imprint, imprint_len, tst_info)))
        goto err;
    if ((flags & TS_VFY_NONCE)
        && !ts_check_nonces(ctx->nonce, tst_info))
        goto err;
    if ((flags & TS_VFY_SIGNER)
        && tsa_name && !ts_check_signer_name(tsa_name, signer)) {
        TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_NAME_MISMATCH);
        goto err;
    }
    if ((flags & TS_VFY_TSA_NAME)
        && !ts_check_signer_name(ctx->tsa_name, signer)) {
        TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_UNTRUSTED);
        goto err;
    }
    ret = 1;

 err:
    X509_free(signer);
    X509_ALGOR_free(md_alg);
    OPENSSL_free(imprint);
    return ret;
}

static int ts_check_status_info(TS_RESP *response)
{
    TS_STATUS_INFO *info = response->status_info;
    long status = ASN1_INTEGER_get(info->status);
    const char *status_text = NULL;
    char *embedded_status_text = NULL;
    char failure_text[TS_STATUS_BUF_SIZE] = "";

    if (status == 0 || status == 1)
        return 1;

    /* There was an error, get the description in status_text. */
    if (0 <= status && status < (long) OSSL_NELEM(ts_status_text))
        status_text = ts_status_text[status];
    else
        status_text = "unknown code";

    if (sk_ASN1_UTF8STRING_num(info->text) > 0
        && (embedded_status_text = ts_get_status_text(info->text)) == NULL)
        return 0;

    /* Fill in failure_text with the failure information. */
    if (info->failure_info) {
        int i;
        int first = 1;
        for (i = 0; i < (int)OSSL_NELEM(ts_failure_info); ++i) {
            if (ASN1_BIT_STRING_get_bit(info->failure_info,
                                        ts_failure_info[i].code)) {
                if (!first)
                    strcat(failure_text, ",");
                else
                    first = 0;
                strcat(failure_text, ts_failure_info[i].text);
            }
        }
    }
    if (failure_text[0] == '\0')
        strcpy(failure_text, "unspecified");

    TSerr(TS_F_TS_CHECK_STATUS_INFO, TS_R_NO_TIME_STAMP_TOKEN);
    ERR_add_error_data(6,
                       "status code: ", status_text,
                       ", status text: ", embedded_status_text ?
                       embedded_status_text : "unspecified",
                       ", failure codes: ", failure_text);
    OPENSSL_free(embedded_status_text);

    return 0;
}

static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text)
{
    int i;
    int length = 0;
    char *result = NULL;
    char *p;

    for (i = 0; i < sk_ASN1_UTF8STRING_num(text); ++i) {
        ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
        if (ASN1_STRING_length(current) > TS_MAX_STATUS_LENGTH - length - 1)
            return NULL;
        length += ASN1_STRING_length(current);
        length += 1;            /* separator character */
    }
    if ((result = OPENSSL_malloc(length)) == NULL) {
        TSerr(TS_F_TS_GET_STATUS_TEXT, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    for (i = 0, p = result; i < sk_ASN1_UTF8STRING_num(text); ++i) {
        ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
        length = ASN1_STRING_length(current);
        if (i > 0)
            *p++ = '/';
        strncpy(p, (const char *)ASN1_STRING_get0_data(current), length);
        p += length;
    }
    *p = '\0';

    return result;
}

static int ts_check_policy(const ASN1_OBJECT *req_oid,
                           const TS_TST_INFO *tst_info)
{
    const ASN1_OBJECT *resp_oid = tst_info->policy_id;

    if (OBJ_cmp(req_oid, resp_oid) != 0) {
        TSerr(TS_F_TS_CHECK_POLICY, TS_R_POLICY_MISMATCH);
        return 0;
    }

    return 1;
}

static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
                              X509_ALGOR **md_alg,
                              unsigned char **imprint, unsigned *imprint_len)
{
    TS_MSG_IMPRINT *msg_imprint = tst_info->msg_imprint;
    X509_ALGOR *md_alg_resp = msg_imprint->hash_algo;
    const EVP_MD *md;
    EVP_MD_CTX *md_ctx = NULL;
    unsigned char buffer[4096];
    int length;

    *md_alg = NULL;
    *imprint = NULL;

    if ((*md_alg = X509_ALGOR_dup(md_alg_resp)) == NULL)
        goto err;
    if ((md = EVP_get_digestbyobj((*md_alg)->algorithm)) == NULL) {
        TSerr(TS_F_TS_COMPUTE_IMPRINT, TS_R_UNSUPPORTED_MD_ALGORITHM);
        goto err;
    }
    length = EVP_MD_size(md);
    if (length < 0)
        goto err;
    *imprint_len = length;
    if ((*imprint = OPENSSL_malloc(*imprint_len)) == NULL) {
        TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    md_ctx = EVP_MD_CTX_new();
    if (md_ctx == NULL) {
        TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    if (!EVP_DigestInit(md_ctx, md))
        goto err;
    while ((length = BIO_read(data, buffer, sizeof(buffer))) > 0) {
        if (!EVP_DigestUpdate(md_ctx, buffer, length))
            goto err;
    }
    if (!EVP_DigestFinal(md_ctx, *imprint, NULL))
        goto err;
    EVP_MD_CTX_free(md_ctx);

    return 1;
 err:
    EVP_MD_CTX_free(md_ctx);
    X509_ALGOR_free(*md_alg);
    OPENSSL_free(*imprint);
    *imprint_len = 0;
    *imprint = 0;
    return 0;
}

static int ts_check_imprints(X509_ALGOR *algor_a,
                             const unsigned char *imprint_a, unsigned len_a,
                             TS_TST_INFO *tst_info)
{
    TS_MSG_IMPRINT *b = tst_info->msg_imprint;
    X509_ALGOR *algor_b = b->hash_algo;
    int ret = 0;

    if (algor_a) {
        if (OBJ_cmp(algor_a->algorithm, algor_b->algorithm))
            goto err;

        /* The parameter must be NULL in both. */
        if ((algor_a->parameter
             && ASN1_TYPE_get(algor_a->parameter) != V_ASN1_NULL)
            || (algor_b->parameter
                && ASN1_TYPE_get(algor_b->parameter) != V_ASN1_NULL))
            goto err;
    }

    ret = len_a == (unsigned)ASN1_STRING_length(b->hashed_msg) &&
        memcmp(imprint_a, ASN1_STRING_get0_data(b->hashed_msg), len_a) == 0;
 err:
    if (!ret)
        TSerr(TS_F_TS_CHECK_IMPRINTS, TS_R_MESSAGE_IMPRINT_MISMATCH);
    return ret;
}

static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info)
{
    const ASN1_INTEGER *b = tst_info->nonce;

    if (!b) {
        TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_NOT_RETURNED);
        return 0;
    }

    /* No error if a nonce is returned without being requested. */
    if (ASN1_INTEGER_cmp(a, b) != 0) {
        TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_MISMATCH);
        return 0;
    }

    return 1;
}

/*
 * Check if the specified TSA name matches either the subject or one of the
 * subject alternative names of the TSA certificate.
 */
static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer)
{
    STACK_OF(GENERAL_NAME) *gen_names = NULL;
    int idx = -1;
    int found = 0;

    if (tsa_name->type == GEN_DIRNAME
        && X509_name_cmp(tsa_name->d.dirn, X509_get_subject_name(signer)) == 0)
        return 1;
    gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
    while (gen_names != NULL) {
        found = ts_find_name(gen_names, tsa_name) >= 0;
        if (found)
            break;
        /*
         * Get the next subject alternative name, although there should be no
         * more than one.
         */
        GENERAL_NAMES_free(gen_names);
        gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
    }
    GENERAL_NAMES_free(gen_names);

    return found;
}

/* Returns 1 if name is in gen_names, 0 otherwise. */
static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name)
{
    int i, found;
    for (i = 0, found = 0; !found && i < sk_GENERAL_NAME_num(gen_names); ++i) {
        GENERAL_NAME *current = sk_GENERAL_NAME_value(gen_names, i);
        found = GENERAL_NAME_cmp(current, name) == 0;
    }
    return found ? i - 1 : -1;
}