crypto/ts/ts_rsp_verify.c

   1 /* crypto/ts/ts_resp_verify.c */
   2 /*
   3  * Written by Zoltan Glozik (zglozik@stones.com) for the OpenSSL project
   4  * 2002.
   5  */
   6 /* ====================================================================
   7  * Copyright (c) 2006 The OpenSSL Project.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  *
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in
  18  *    the documentation and/or other materials provided with the
  19  *    distribution.
  20  *
  21  * 3. All advertising materials mentioning features or use of this
  22  *    software must display the following acknowledgment:
  23  *    "This product includes software developed by the OpenSSL Project
  24  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  25  *
  26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  27  *    endorse or promote products derived from this software without
  28  *    prior written permission. For written permission, please contact
  29  *    licensing@OpenSSL.org.
  30  *
  31  * 5. Products derived from this software may not be called "OpenSSL"
  32  *    nor may "OpenSSL" appear in their names without prior written
  33  *    permission of the OpenSSL Project.
  34  *
  35  * 6. Redistributions of any form whatsoever must retain the following
  36  *    acknowledgment:
  37  *    "This product includes software developed by the OpenSSL Project
  38  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  51  * OF THE POSSIBILITY OF SUCH DAMAGE.
  52  * ====================================================================
  53  *
  54  * This product includes cryptographic software written by Eric Young
  55  * (eay@cryptsoft.com).  This product includes software written by Tim
  56  * Hudson (tjh@cryptsoft.com).
  57  *
  58  */
  59
  60 #include <stdio.h>
  61 #include "internal/cryptlib.h"
  62 #include <openssl/objects.h>
  63 #include <openssl/ts.h>
  64 #include <openssl/pkcs7.h>
  65 #include "ts_lcl.h"
  66
  67 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
  68                           X509 *signer, STACK_OF(X509) **chain);
  69 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
  70                                   STACK_OF(X509) *chain);
  71 static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si);
  72 static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert);
  73 static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert);
  74 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
  75                                     PKCS7 *token, TS_TST_INFO *tst_info);
  76 static int ts_check_status_info(TS_RESP *response);
  77 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text);
  78 static int ts_check_policy(ASN1_OBJECT *req_oid, TS_TST_INFO *tst_info);
  79 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
  80                               X509_ALGOR **md_alg,
  81                               unsigned char **imprint, unsigned *imprint_len);
  82 static int ts_check_imprints(X509_ALGOR *algor_a,
  83                              unsigned char *imprint_a, unsigned len_a,
  84                              TS_TST_INFO *tst_info);
  85 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info);
  86 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer);
  87 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names,
  88                         GENERAL_NAME *name);
  89
  90 /*
  91  * This must be large enough to hold all values in ts_status_text (with
  92  * comma separator) or all text fields in ts_failure_info (also with comma).
  93  */
  94 #define TS_STATUS_BUF_SIZE      256
  95
  96 /*
  97  * Local mapping between response codes and descriptions.
  98  */
  99 static const char *ts_status_text[] = {
 100     "granted",
 101     "grantedWithMods",
 102     "rejection",
 103     "waiting",
 104     "revocationWarning",
 105     "revocationNotification"
 106 };
 107
 108 #define TS_STATUS_TEXT_SIZE     OSSL_NELEM(ts_status_text)
 109
 110 static struct {
 111     int code;
 112     const char *text;
 113 } ts_failure_info[] = {
 114     {TS_INFO_BAD_ALG, "badAlg"},
 115     {TS_INFO_BAD_REQUEST, "badRequest"},
 116     {TS_INFO_BAD_DATA_FORMAT, "badDataFormat"},
 117     {TS_INFO_TIME_NOT_AVAILABLE, "timeNotAvailable"},
 118     {TS_INFO_UNACCEPTED_POLICY, "unacceptedPolicy"},
 119     {TS_INFO_UNACCEPTED_EXTENSION, "unacceptedExtension"},
 120     {TS_INFO_ADD_INFO_NOT_AVAILABLE, "addInfoNotAvailable"},
 121     {TS_INFO_SYSTEM_FAILURE, "systemFailure"}
 122 };
 123
 124
 125 /*-
 126  * This function carries out the following tasks:
 127  *      - Checks if there is one and only one signer.
 128  *      - Search for the signing certificate in 'certs' and in the response.
 129  *      - Check the extended key usage and key usage fields of the signer
 130  *      certificate (done by the path validation).
 131  *      - Build and validate the certificate path.
 132  *      - Check if the certificate path meets the requirements of the
 133  *      SigningCertificate ESS signed attribute.
 134  *      - Verify the signature value.
 135  *      - Returns the signer certificate in 'signer', if 'signer' is not NULL.
 136  */
 137 int TS_RESP_verify_signature(PKCS7 *token, STACK_OF(X509) *certs,
 138                              X509_STORE *store, X509 **signer_out)
 139 {
 140     STACK_OF(PKCS7_SIGNER_INFO) *sinfos = NULL;
 141     PKCS7_SIGNER_INFO *si;
 142     STACK_OF(X509) *signers = NULL;
 143     X509 *signer;
 144     STACK_OF(X509) *chain = NULL;
 145     char buf[4096];
 146     int i, j = 0, ret = 0;
 147     BIO *p7bio = NULL;
 148
 149     /* Some sanity checks first. */
 150     if (!token) {
 151         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_INVALID_NULL_POINTER);
 152         goto err;
 153     }
 154     if (!PKCS7_type_is_signed(token)) {
 155         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_WRONG_CONTENT_TYPE);
 156         goto err;
 157     }
 158     sinfos = PKCS7_get_signer_info(token);
 159     if (!sinfos || sk_PKCS7_SIGNER_INFO_num(sinfos) != 1) {
 160         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_THERE_MUST_BE_ONE_SIGNER);
 161         goto err;
 162     }
 163     si = sk_PKCS7_SIGNER_INFO_value(sinfos, 0);
 164     if (PKCS7_get_detached(token)) {
 165         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_NO_CONTENT);
 166         goto err;
 167     }
 168
 169     /*
 170      * Get hold of the signer certificate, search only internal certificates
 171      * if it was requested.
 172      */
 173     signers = PKCS7_get0_signers(token, certs, 0);
 174     if (!signers || sk_X509_num(signers) != 1)
 175         goto err;
 176     signer = sk_X509_value(signers, 0);
 177
 178     if (!ts_verify_cert(store, certs, signer, &chain))
 179         goto err;
 180     if (!ts_check_signing_certs(si, chain))
 181         goto err;
 182     p7bio = PKCS7_dataInit(token, NULL);
 183
 184     /* We now have to 'read' from p7bio to calculate digests etc. */
 185     while ((i = BIO_read(p7bio, buf, sizeof(buf))) > 0)
 186         continue;
 187
 188     j = PKCS7_signatureVerify(p7bio, token, si, signer);
 189     if (j <= 0) {
 190         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_SIGNATURE_FAILURE);
 191         goto err;
 192     }
 193
 194     if (signer_out) {
 195         *signer_out = signer;
 196         X509_up_ref(signer);
 197     }
 198     ret = 1;
 199
 200  err:
 201     BIO_free_all(p7bio);
 202     sk_X509_pop_free(chain, X509_free);
 203     sk_X509_free(signers);
 204
 205     return ret;
 206 }
 207
 208 /*
 209  * The certificate chain is returned in chain. Caller is responsible for
 210  * freeing the vector.
 211  */
 212 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
 213                           X509 *signer, STACK_OF(X509) **chain)
 214 {
 215     X509_STORE_CTX cert_ctx;
 216     int i;
 217     int ret = 1;
 218
 219     *chain = NULL;
 220     X509_STORE_CTX_init(&cert_ctx, store, signer, untrusted);
 221     X509_STORE_CTX_set_purpose(&cert_ctx, X509_PURPOSE_TIMESTAMP_SIGN);
 222     i = X509_verify_cert(&cert_ctx);
 223     if (i <= 0) {
 224         int j = X509_STORE_CTX_get_error(&cert_ctx);
 225         TSerr(TS_F_TS_VERIFY_CERT, TS_R_CERTIFICATE_VERIFY_ERROR);
 226         ERR_add_error_data(2, "Verify error:",
 227                            X509_verify_cert_error_string(j));
 228         ret = 0;
 229     } else {
 230         *chain = X509_STORE_CTX_get1_chain(&cert_ctx);
 231     }
 232
 233     X509_STORE_CTX_cleanup(&cert_ctx);
 234
 235     return ret;
 236 }
 237
 238 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
 239                                   STACK_OF(X509) *chain)
 240 {
 241     ESS_SIGNING_CERT *ss = ess_get_signing_cert(si);
 242     STACK_OF(ESS_CERT_ID) *cert_ids = NULL;
 243     X509 *cert;
 244     int i = 0;
 245     int ret = 0;
 246
 247     if (!ss)
 248         goto err;
 249     cert_ids = ss->cert_ids;
 250     cert = sk_X509_value(chain, 0);
 251     if (ts_find_cert(cert_ids, cert) != 0)
 252         goto err;
 253
 254     /*
 255      * Check the other certificates of the chain if there are more than one
 256      * certificate ids in cert_ids.
 257      */
 258     if (sk_ESS_CERT_ID_num(cert_ids) > 1) {
 259         for (i = 1; i < sk_X509_num(chain); ++i) {
 260             cert = sk_X509_value(chain, i);
 261             if (ts_find_cert(cert_ids, cert) < 0)
 262                 goto err;
 263         }
 264     }
 265     ret = 1;
 266  err:
 267     if (!ret)
 268         TSerr(TS_F_TS_CHECK_SIGNING_CERTS,
 269               TS_R_ESS_SIGNING_CERTIFICATE_ERROR);
 270     ESS_SIGNING_CERT_free(ss);
 271     return ret;
 272 }
 273
 274 static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si)
 275 {
 276     ASN1_TYPE *attr;
 277     const unsigned char *p;
 278     attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificate);
 279     if (!attr)
 280         return NULL;
 281     p = attr->value.sequence->data;
 282     return d2i_ESS_SIGNING_CERT(NULL, &p, attr->value.sequence->length);
 283 }
 284
 285 /* Returns < 0 if certificate is not found, certificate index otherwise. */
 286 static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert)
 287 {
 288     int i;
 289     unsigned char cert_sha1[SHA_DIGEST_LENGTH];
 290
 291     if (!cert_ids || !cert)
 292         return -1;
 293
 294     X509_digest(cert, EVP_sha1(), cert_sha1, NULL);
 295
 296     /* Recompute SHA1 hash of certificate if necessary (side effect). */
 297     X509_check_purpose(cert, -1, 0);
 298
 299     /* Look for cert in the cert_ids vector. */
 300     for (i = 0; i < sk_ESS_CERT_ID_num(cert_ids); ++i) {
 301         ESS_CERT_ID *cid = sk_ESS_CERT_ID_value(cert_ids, i);
 302
 303         if (cid->hash->length == SHA_DIGEST_LENGTH
 304             && memcmp(cid->hash->data, cert_sha1, SHA_DIGEST_LENGTH) == 0) {
 305             ESS_ISSUER_SERIAL *is = cid->issuer_serial;
 306             if (!is || !ts_issuer_serial_cmp(is, cert))
 307                 return i;
 308         }
 309     }
 310
 311     return -1;
 312 }
 313
 314 static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert)
 315 {
 316     GENERAL_NAME *issuer;
 317
 318     if (!is || !cert || sk_GENERAL_NAME_num(is->issuer) != 1)
 319         return -1;
 320
 321     issuer = sk_GENERAL_NAME_value(is->issuer, 0);
 322     if (issuer->type != GEN_DIRNAME
 323         || X509_NAME_cmp(issuer->d.dirn, X509_get_issuer_name(cert)))
 324         return -1;
 325
 326     if (ASN1_INTEGER_cmp(is->serial, X509_get_serialNumber(cert)))
 327         return -1;
 328
 329     return 0;
 330 }
 331
 332 /*-
 333  * Verifies whether 'response' contains a valid response with regards
 334  * to the settings of the context:
 335  *      - Gives an error message if the TS_TST_INFO is not present.
 336  *      - Calls _TS_RESP_verify_token to verify the token content.
 337  */
 338 int TS_RESP_verify_response(TS_VERIFY_CTX *ctx, TS_RESP *response)
 339 {
 340     PKCS7 *token = response->token;
 341     TS_TST_INFO *tst_info = response->tst_info;
 342     int ret = 0;
 343
 344     if (!ts_check_status_info(response))
 345         goto err;
 346     if (!int_ts_RESP_verify_token(ctx, token, tst_info))
 347         goto err;
 348     ret = 1;
 349
 350  err:
 351     return ret;
 352 }
 353
 354 /*
 355  * Tries to extract a TS_TST_INFO structure from the PKCS7 token and
 356  * calls the internal int_TS_RESP_verify_token function for verifying it.
 357  */
 358 int TS_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token)
 359 {
 360     TS_TST_INFO *tst_info = PKCS7_to_TS_TST_INFO(token);
 361     int ret = 0;
 362     if (tst_info) {
 363         ret = int_ts_RESP_verify_token(ctx, token, tst_info);
 364         TS_TST_INFO_free(tst_info);
 365     }
 366     return ret;
 367 }
 368
 369 /*-
 370  * Verifies whether the 'token' contains a valid time stamp token
 371  * with regards to the settings of the context. Only those checks are
 372  * carried out that are specified in the context:
 373  *      - Verifies the signature of the TS_TST_INFO.
 374  *      - Checks the version number of the response.
 375  *      - Check if the requested and returned policies math.
 376  *      - Check if the message imprints are the same.
 377  *      - Check if the nonces are the same.
 378  *      - Check if the TSA name matches the signer.
 379  *      - Check if the TSA name is the expected TSA.
 380  */
 381 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
 382                                     PKCS7 *token, TS_TST_INFO *tst_info)
 383 {
 384     X509 *signer = NULL;
 385     GENERAL_NAME *tsa_name = tst_info->tsa;
 386     X509_ALGOR *md_alg = NULL;
 387     unsigned char *imprint = NULL;
 388     unsigned imprint_len = 0;
 389     int ret = 0;
 390
 391     if ((ctx->flags & TS_VFY_SIGNATURE)
 392         && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer))
 393         goto err;
 394     if ((ctx->flags & TS_VFY_VERSION)
 395         && TS_TST_INFO_get_version(tst_info) != 1) {
 396         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_UNSUPPORTED_VERSION);
 397         goto err;
 398     }
 399     if ((ctx->flags & TS_VFY_POLICY)
 400         && !ts_check_policy(ctx->policy, tst_info))
 401         goto err;
 402     if ((ctx->flags & TS_VFY_IMPRINT)
 403         && !ts_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len,
 404                               tst_info))
 405         goto err;
 406     if ((ctx->flags & TS_VFY_DATA)
 407         && (!ts_compute_imprint(ctx->data, tst_info,
 408                                 &md_alg, &imprint, &imprint_len)
 409             || !ts_check_imprints(md_alg, imprint, imprint_len, tst_info)))
 410         goto err;
 411     if ((ctx->flags & TS_VFY_NONCE)
 412         && !ts_check_nonces(ctx->nonce, tst_info))
 413         goto err;
 414     if ((ctx->flags & TS_VFY_SIGNER)
 415         && tsa_name && !ts_check_signer_name(tsa_name, signer)) {
 416         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_NAME_MISMATCH);
 417         goto err;
 418     }
 419     if ((ctx->flags & TS_VFY_TSA_NAME)
 420         && !ts_check_signer_name(ctx->tsa_name, signer)) {
 421         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_UNTRUSTED);
 422         goto err;
 423     }
 424     ret = 1;
 425
 426  err:
 427     X509_free(signer);
 428     X509_ALGOR_free(md_alg);
 429     OPENSSL_free(imprint);
 430     return ret;
 431 }
 432
 433 static int ts_check_status_info(TS_RESP *response)
 434 {
 435     TS_STATUS_INFO *info = response->status_info;
 436     long status = ASN1_INTEGER_get(info->status);
 437     const char *status_text = NULL;
 438     char *embedded_status_text = NULL;
 439     char failure_text[TS_STATUS_BUF_SIZE] = "";
 440
 441     if (status == 0 || status == 1)
 442         return 1;
 443
 444     /* There was an error, get the description in status_text. */
 445     if (0 <= status && status < (long) OSSL_NELEM(ts_status_text))
 446         status_text = ts_status_text[status];
 447     else
 448         status_text = "unknown code";
 449
 450     if (sk_ASN1_UTF8STRING_num(info->text) > 0
 451         && (embedded_status_text = ts_get_status_text(info->text)) == NULL)
 452         return 0;
 453
 454     /* Fill in failure_text with the failure information. */
 455     if (info->failure_info) {
 456         int i;
 457         int first = 1;
 458         for (i = 0; i < (int)OSSL_NELEM(ts_failure_info); ++i) {
 459             if (ASN1_BIT_STRING_get_bit(info->failure_info,
 460                                         ts_failure_info[i].code)) {
 461                 if (!first)
 462                     strcat(failure_text, ",");
 463                 else
 464                     first = 0;
 465                 strcat(failure_text, ts_failure_info[i].text);
 466             }
 467         }
 468     }
 469     if (failure_text[0] == '\0')
 470         strcpy(failure_text, "unspecified");
 471
 472     TSerr(TS_F_TS_CHECK_STATUS_INFO, TS_R_NO_TIME_STAMP_TOKEN);
 473     ERR_add_error_data(6,
 474                        "status code: ", status_text,
 475                        ", status text: ", embedded_status_text ?
 476                        embedded_status_text : "unspecified",
 477                        ", failure codes: ", failure_text);
 478     OPENSSL_free(embedded_status_text);
 479
 480     return 0;
 481 }
 482
 483 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text)
 484 {
 485     int i;
 486     unsigned int length = 0;
 487     char *result = NULL;
 488     char *p;
 489
 490     for (i = 0; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 491         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 492         length += ASN1_STRING_length(current);
 493         length += 1;            /* separator character */
 494     }
 495     if ((result = OPENSSL_malloc(length)) == NULL) {
 496         TSerr(TS_F_TS_GET_STATUS_TEXT, ERR_R_MALLOC_FAILURE);
 497         return NULL;
 498     }
 499
 500     for (i = 0, p = result; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 501         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 502         length = ASN1_STRING_length(current);
 503         if (i > 0)
 504             *p++ = '/';
 505         strncpy(p, (const char *)ASN1_STRING_data(current), length);
 506         p += length;
 507     }
 508     *p = '\0';
 509
 510     return result;
 511 }
 512
 513 static int ts_check_policy(ASN1_OBJECT *req_oid, TS_TST_INFO *tst_info)
 514 {
 515     ASN1_OBJECT *resp_oid = tst_info->policy_id;
 516
 517     if (OBJ_cmp(req_oid, resp_oid) != 0) {
 518         TSerr(TS_F_TS_CHECK_POLICY, TS_R_POLICY_MISMATCH);
 519         return 0;
 520     }
 521
 522     return 1;
 523 }
 524
 525 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
 526                               X509_ALGOR **md_alg,
 527                               unsigned char **imprint, unsigned *imprint_len)
 528 {
 529     TS_MSG_IMPRINT *msg_imprint = tst_info->msg_imprint;
 530     X509_ALGOR *md_alg_resp = msg_imprint->hash_algo;
 531     const EVP_MD *md;
 532     EVP_MD_CTX *md_ctx = NULL;
 533     unsigned char buffer[4096];
 534     int length;
 535
 536     *md_alg = NULL;
 537     *imprint = NULL;
 538
 539     if ((*md_alg = X509_ALGOR_dup(md_alg_resp)) == NULL)
 540         goto err;
 541     if ((md = EVP_get_digestbyobj((*md_alg)->algorithm)) == NULL) {
 542         TSerr(TS_F_TS_COMPUTE_IMPRINT, TS_R_UNSUPPORTED_MD_ALGORITHM);
 543         goto err;
 544     }
 545     length = EVP_MD_size(md);
 546     if (length < 0)
 547         goto err;
 548     *imprint_len = length;
 549     if ((*imprint = OPENSSL_malloc(*imprint_len)) == NULL) {
 550         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 551         goto err;
 552     }
 553
 554     md_ctx = EVP_MD_CTX_new();
 555     if (md_ctx == NULL) {
 556         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 557         goto err;
 558     }
 559     if (!EVP_DigestInit(md_ctx, md))
 560         goto err;
 561     while ((length = BIO_read(data, buffer, sizeof(buffer))) > 0) {
 562         if (!EVP_DigestUpdate(md_ctx, buffer, length))
 563             goto err;
 564     }
 565     if (!EVP_DigestFinal(md_ctx, *imprint, NULL))
 566         goto err;
 567     EVP_MD_CTX_free(md_ctx);
 568
 569     return 1;
 570  err:
 571     EVP_MD_CTX_free(md_ctx);
 572     X509_ALGOR_free(*md_alg);
 573     OPENSSL_free(*imprint);
 574     *imprint_len = 0;
 575     *imprint = 0;
 576     return 0;
 577 }
 578
 579 static int ts_check_imprints(X509_ALGOR *algor_a,
 580                              unsigned char *imprint_a, unsigned len_a,
 581                              TS_TST_INFO *tst_info)
 582 {
 583     TS_MSG_IMPRINT *b = tst_info->msg_imprint;
 584     X509_ALGOR *algor_b = b->hash_algo;
 585     int ret = 0;
 586
 587     if (algor_a) {
 588         if (OBJ_cmp(algor_a->algorithm, algor_b->algorithm))
 589             goto err;
 590
 591         /* The parameter must be NULL in both. */
 592         if ((algor_a->parameter
 593              && ASN1_TYPE_get(algor_a->parameter) != V_ASN1_NULL)
 594             || (algor_b->parameter
 595                 && ASN1_TYPE_get(algor_b->parameter) != V_ASN1_NULL))
 596             goto err;
 597     }
 598
 599     ret = len_a == (unsigned)ASN1_STRING_length(b->hashed_msg) &&
 600         memcmp(imprint_a, ASN1_STRING_data(b->hashed_msg), len_a) == 0;
 601  err:
 602     if (!ret)
 603         TSerr(TS_F_TS_CHECK_IMPRINTS, TS_R_MESSAGE_IMPRINT_MISMATCH);
 604     return ret;
 605 }
 606
 607 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info)
 608 {
 609     const ASN1_INTEGER *b = tst_info->nonce;
 610
 611     if (!b) {
 612         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_NOT_RETURNED);
 613         return 0;
 614     }
 615
 616     /* No error if a nonce is returned without being requested. */
 617     if (ASN1_INTEGER_cmp(a, b) != 0) {
 618         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_MISMATCH);
 619         return 0;
 620     }
 621
 622     return 1;
 623 }
 624
 625 /*
 626  * Check if the specified TSA name matches either the subject or one of the
 627  * subject alternative names of the TSA certificate.
 628  */
 629 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer)
 630 {
 631     STACK_OF(GENERAL_NAME) *gen_names = NULL;
 632     int idx = -1;
 633     int found = 0;
 634
 635     if (tsa_name->type == GEN_DIRNAME
 636         && X509_name_cmp(tsa_name->d.dirn, X509_get_subject_name(signer)) == 0)
 637         return 1;
 638     gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 639     while (gen_names != NULL) {
 640         found = ts_find_name(gen_names, tsa_name) >= 0;
 641         if (found)
 642             break;
 643         /*
 644          * Get the next subject alternative name, although there should be no
 645          * more than one.
 646          */
 647         GENERAL_NAMES_free(gen_names);
 648         gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 649     }
 650     GENERAL_NAMES_free(gen_names);
 651
 652     return found;
 653 }
 654
 655 /* Returns 1 if name is in gen_names, 0 otherwise. */
 656 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name)
 657 {
 658     int i, found;
 659     for (i = 0, found = 0; !found && i < sk_GENERAL_NAME_num(gen_names); ++i) {
 660         GENERAL_NAME *current = sk_GENERAL_NAME_value(gen_names, i);
 661         found = GENERAL_NAME_cmp(current, name) == 0;
 662     }
 663     return found ? i - 1 : -1;
 664 }