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dirmngr: Allow for other hash algorithms than SHA-1 in OCSP.
* dirmngr/ocsp.c (do_ocsp_request): Remove arg md. Add args r_sigval, r_produced_at, and r_md. Get the hash algo from the signature and create the context here. (check_signature): Allow any hash algo. Print a diagnostic if the signature does not verify. -- GnuPG-bug-id: 3966 Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch
parent
4699e294cc
commit
405f41007c
105
dirmngr/ocsp.c
105
dirmngr/ocsp.c
@ -116,10 +116,15 @@ read_response (estream_t fp, unsigned char **r_buffer, size_t *r_buflen)
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/* Construct an OCSP request, send it to the configured OCSP responder
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and parse the response. On success the OCSP context may be used to
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further process the response. */
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further process the response. The signature value and the
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production date are returned at R_SIGVAL and R_PRODUCED_AT; they
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may be NULL or an empty string if not available. A new hash
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context is returned at R_MD. */
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static gpg_error_t
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do_ocsp_request (ctrl_t ctrl, ksba_ocsp_t ocsp, gcry_md_hd_t md,
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const char *url, ksba_cert_t cert, ksba_cert_t issuer_cert)
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do_ocsp_request (ctrl_t ctrl, ksba_ocsp_t ocsp,
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const char *url, ksba_cert_t cert, ksba_cert_t issuer_cert,
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ksba_sexp_t *r_sigval, ksba_isotime_t r_produced_at,
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gcry_md_hd_t *r_md)
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{
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gpg_error_t err;
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unsigned char *request, *response;
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@ -132,6 +137,10 @@ do_ocsp_request (ctrl_t ctrl, ksba_ocsp_t ocsp, gcry_md_hd_t md,
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(void)ctrl;
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*r_sigval = NULL;
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*r_produced_at = 0;
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*r_md = NULL;
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if (dirmngr_use_tor ())
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{
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/* For now we do not allow OCSP via Tor due to possible privacy
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@ -263,6 +272,7 @@ do_ocsp_request (ctrl_t ctrl, ksba_ocsp_t ocsp, gcry_md_hd_t md,
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xfree (free_this);
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return err;
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}
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/* log_printhex (response, responselen, "ocsp response"); */
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err = ksba_ocsp_parse_response (ocsp, response, responselen,
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&response_status);
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@ -290,11 +300,34 @@ do_ocsp_request (ctrl_t ctrl, ksba_ocsp_t ocsp, gcry_md_hd_t md,
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}
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if (response_status == KSBA_OCSP_RSPSTATUS_SUCCESS)
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{
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int hash_algo;
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if (opt.verbose)
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log_info (_("OCSP responder at '%s' status: %s\n"), url, t);
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/* Get the signature value now because we can all this fucntion
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* only once. */
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*r_sigval = ksba_ocsp_get_sig_val (ocsp, r_produced_at);
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hash_algo = hash_algo_from_sigval (*r_sigval);
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if (!hash_algo)
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{
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if (opt.verbose)
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log_info ("ocsp: using SHA-256 as fallback hash algo.\n");
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hash_algo = GCRY_MD_SHA256;
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}
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err = gcry_md_open (r_md, hash_algo, 0);
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if (err)
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{
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log_error (_("failed to establish a hashing context for OCSP: %s\n"),
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gpg_strerror (err));
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goto leave;
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}
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if (DBG_HASHING)
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gcry_md_debug (*r_md, "ocsp");
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err = ksba_ocsp_hash_response (ocsp, response, responselen,
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HASH_FNC, md);
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HASH_FNC, *r_md);
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if (err)
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log_error (_("hashing the OCSP response for '%s' failed: %s\n"),
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url, gpg_strerror (err));
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@ -305,8 +338,17 @@ do_ocsp_request (ctrl_t ctrl, ksba_ocsp_t ocsp, gcry_md_hd_t md,
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err = gpg_error (GPG_ERR_GENERAL);
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}
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leave:
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xfree (response);
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xfree (free_this);
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if (err)
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{
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xfree (*r_sigval);
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*r_sigval = NULL;
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*r_produced_at = 0;
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gcry_md_close (*r_md);
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*r_md = NULL;
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}
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return err;
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}
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@ -391,7 +433,7 @@ check_signature_core (ctrl_t ctrl, ksba_cert_t cert, gcry_sexp_t s_sig,
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/* We simply ignore all errors. */
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gcry_sexp_release (s_pkey);
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return -1;
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return err;
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}
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@ -410,18 +452,27 @@ check_signature (ctrl_t ctrl,
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int algo, cert_idx;
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gcry_sexp_t s_hash;
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ksba_cert_t cert;
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const char *s;
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/* Create a suitable S-expression with the hash value of our response. */
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gcry_md_final (md);
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algo = gcry_md_get_algo (md);
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if (algo != GCRY_MD_SHA1 )
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s = gcry_md_algo_name (algo);
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if (algo && s && strlen (s) < 16)
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{
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log_error (_("only SHA-1 is supported for OCSP responses\n"));
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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err = gcry_sexp_build (&s_hash, NULL, "(data(flags pkcs1)(hash sha1 %b))",
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gcry_md_get_algo_dlen (algo),
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char hashalgostr[16+1];
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int i;
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for (i=0; s[i]; i++)
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hashalgostr[i] = ascii_tolower (s[i]);
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hashalgostr[i] = 0;
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err = gcry_sexp_build (&s_hash, NULL, "(data(flags pkcs1)(hash %s %b))",
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hashalgostr,
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(int)gcry_md_get_algo_dlen (algo),
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gcry_md_read (md, algo));
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}
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else
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err = gpg_error (GPG_ERR_DIGEST_ALGO);
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if (err)
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{
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log_error (_("creating S-expression failed: %s\n"), gcry_strerror (err));
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@ -465,6 +516,7 @@ check_signature (ctrl_t ctrl,
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{
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cert_ref_t cref;
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/* dump_cert ("from ocsp response", cert); */
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cref = xtrymalloc (sizeof *cref);
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if (!cref)
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log_error (_("allocating list item failed: %s\n"),
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@ -500,8 +552,6 @@ check_signature (ctrl_t ctrl,
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}
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log_printf ("not found\n");
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}
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ksba_free (name);
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ksba_free (keyid);
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if (cert)
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{
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@ -510,10 +560,24 @@ check_signature (ctrl_t ctrl,
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ksba_cert_release (cert);
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if (!err)
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{
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ksba_free (name);
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ksba_free (keyid);
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gcry_sexp_release (s_hash);
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return 0; /* Successfully verified the signature. */
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}
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log_error ("responder certificate ");
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if (name)
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log_printf ("'/%s' ", name);
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if (keyid)
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{
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log_printf ("{");
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dump_serial (keyid);
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log_printf ("} ");
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}
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log_printf ("did not verify: %s\n", gpg_strerror (err));
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}
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ksba_free (name);
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ksba_free (keyid);
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}
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gcry_sexp_release (s_hash);
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@ -588,8 +652,6 @@ ocsp_isvalid (ctrl_t ctrl, ksba_cert_t cert, const char *cert_fpr,
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goto leave;
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}
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/* Figure out the OCSP responder to use.
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1. Try to get the reponder from the certificate.
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We do only take http and https style URIs into account.
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@ -646,14 +708,8 @@ ocsp_isvalid (ctrl_t ctrl, ksba_cert_t cert, const char *cert_fpr,
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}
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/* Ask the OCSP responder. */
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err = gcry_md_open (&md, GCRY_MD_SHA1, 0);
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if (err)
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{
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log_error (_("failed to establish a hashing context for OCSP: %s\n"),
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gpg_strerror (err));
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goto leave;
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}
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err = do_ocsp_request (ctrl, ocsp, md, url, cert, issuer_cert);
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err = do_ocsp_request (ctrl, ocsp, url, cert, issuer_cert,
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&sigval, produced_at, &md);
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if (err)
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goto leave;
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@ -685,8 +741,7 @@ ocsp_isvalid (ctrl_t ctrl, ksba_cert_t cert, const char *cert_fpr,
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}
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/* We got a useful answer, check that the answer has a valid signature. */
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sigval = ksba_ocsp_get_sig_val (ocsp, produced_at);
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if (!sigval || !*produced_at)
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if (!sigval || !*produced_at || !md)
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{
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err = gpg_error (GPG_ERR_INV_OBJ);
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goto leave;
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