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sm,dirmngr: Support rsaPSS signature verification.
* sm/certcheck.c (hash_algo_from_buffer): New. (uint_from_buffer): New. (gpgsm_check_cert_sig): Handle PSS. * dirmngr/crlcache.c (hash_algo_from_buffer): New. (uint_from_buffer): New. (start_sig_check): Detect PSS and extract hash algo. New arg to return a PSS flag. (finish_sig_check): New arg use_pss. Extract PSS args and use them. (crl_parse_insert): Pass use_pss flag along. -- GnuPG-bug-id: 4538 Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch
parent
5d5b70ae0f
commit
b45ab0ca08
2 changed files with 308 additions and 61 deletions
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@ -1531,17 +1531,104 @@ crl_cache_cert_isvalid (ctrl_t ctrl, ksba_cert_t cert,
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}
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/* Return the hash algorithm's algo id from its name given in the
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* non-null termnated string in (buffer,buflen). Returns 0 on failure
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* or if the algo is not known. */
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static int
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hash_algo_from_buffer (const void *buffer, size_t buflen)
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{
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char *string;
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int algo;
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string = xtrymalloc (buflen + 1);
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if (!string)
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{
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log_error (_("out of core\n"));
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return 0;
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}
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memcpy (string, buffer, buflen);
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string[buflen] = 0;
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algo = gcry_md_map_name (string);
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if (!algo)
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log_error ("unknown digest algorithm '%s' used in certificate\n", string);
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xfree (string);
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return algo;
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}
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/* Return an unsigned integer from the non-null termnated string
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* (buffer,buflen). Returns 0 on failure. */
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static unsigned int
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uint_from_buffer (const void *buffer, size_t buflen)
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{
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char *string;
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unsigned int val;
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string = xtrymalloc (buflen + 1);
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if (!string)
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{
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log_error (_("out of core\n"));
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return 0;
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}
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memcpy (string, buffer, buflen);
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string[buflen] = 0;
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val = strtoul (string, NULL, 10);
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xfree (string);
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return val;
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}
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/* Prepare a hash context for the signature verification. Input is
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the CRL and the output is the hash context MD as well as the uses
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algorithm identifier ALGO. */
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static gpg_error_t
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start_sig_check (ksba_crl_t crl, gcry_md_hd_t *md, int *algo)
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start_sig_check (ksba_crl_t crl, gcry_md_hd_t *md, int *algo, int *use_pss)
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{
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gpg_error_t err;
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const char *algoid;
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*use_pss = 0;
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algoid = ksba_crl_get_digest_algo (crl);
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*algo = gcry_md_map_name (algoid);
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if (algoid && !strcmp (algoid, "1.2.840.113549.1.1.10"))
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{
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/* Parse rsaPSS parameter. */
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gcry_buffer_t ioarray[1] = { {0} };
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ksba_sexp_t pssparam;
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size_t n;
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gcry_sexp_t psssexp;
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pssparam = ksba_crl_get_sig_val (crl);
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n = gcry_sexp_canon_len (pssparam, 0, NULL, NULL);
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if (!n)
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{
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ksba_free (pssparam);
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log_error (_("got an invalid S-expression from libksba\n"));
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return gpg_error (GPG_ERR_INV_SEXP);
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}
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err = gcry_sexp_sscan (&psssexp, NULL, pssparam, n);
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ksba_free (pssparam);
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if (err)
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{
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log_error (_("converting S-expression failed: %s\n"),
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gcry_strerror (err));
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return err;
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}
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err = gcry_sexp_extract_param (psssexp, "sig-val",
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"&'hash-algo'", ioarray, NULL);
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gcry_sexp_release (psssexp);
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if (err)
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{
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log_error ("extracting params from PSS failed: %s\n",
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gpg_strerror (err));
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return err;
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}
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*algo = hash_algo_from_buffer (ioarray[0].data, ioarray[0].len);
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xfree (ioarray[0].data);
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*use_pss = 1;
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}
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else
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*algo = gcry_md_map_name (algoid);
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if (!*algo)
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{
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log_error (_("unknown hash algorithm '%s'\n"), algoid? algoid:"?");
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@ -1570,15 +1657,13 @@ start_sig_check (ksba_crl_t crl, gcry_md_hd_t *md, int *algo)
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certificate of the CRL issuer. This function takes ownership of MD. */
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static gpg_error_t
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finish_sig_check (ksba_crl_t crl, gcry_md_hd_t md, int algo,
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ksba_cert_t issuer_cert)
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ksba_cert_t issuer_cert, int use_pss)
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{
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gpg_error_t err;
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ksba_sexp_t sigval = NULL, pubkey = NULL;
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const char *s;
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char algoname[50];
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size_t n;
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gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL;
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unsigned int i;
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unsigned int saltlen = 0; /* (used only with use_pss) */
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/* This also stops debugging on the MD. */
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gcry_md_final (md);
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@ -1600,6 +1685,55 @@ finish_sig_check (ksba_crl_t crl, gcry_md_hd_t md, int algo,
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goto leave;
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}
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if (use_pss)
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{
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/* Parse rsaPSS parameter which we should find in S_SIG. */
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gcry_buffer_t ioarray[2] = { {0}, {0} };
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ksba_sexp_t pssparam;
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gcry_sexp_t psssexp;
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int hashalgo;
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pssparam = ksba_crl_get_sig_val (crl);
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n = gcry_sexp_canon_len (pssparam, 0, NULL, NULL);
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if (!n)
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{
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ksba_free (pssparam);
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log_error (_("got an invalid S-expression from libksba\n"));
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err = gpg_error (GPG_ERR_INV_SEXP);
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goto leave;
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}
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err = gcry_sexp_sscan (&psssexp, NULL, pssparam, n);
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ksba_free (pssparam);
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if (err)
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{
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log_error (_("converting S-expression failed: %s\n"),
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gcry_strerror (err));
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goto leave;
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}
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err = gcry_sexp_extract_param (psssexp, "sig-val",
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"&'hash-algo''salt-length'",
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ioarray+0, ioarray+1, NULL);
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gcry_sexp_release (psssexp);
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if (err)
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{
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log_error ("extracting params from PSS failed: %s\n",
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gpg_strerror (err));
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goto leave;
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}
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hashalgo = hash_algo_from_buffer (ioarray[0].data, ioarray[0].len);
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saltlen = uint_from_buffer (ioarray[1].data, ioarray[1].len);
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xfree (ioarray[0].data);
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xfree (ioarray[1].data);
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if (hashalgo != algo)
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{
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log_error ("hash algo mismatch: %d announced but %d used\n",
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algo, hashalgo);
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return gpg_error (GPG_ERR_INV_CRL);
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}
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}
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/* Get and convert the public key for the issuer certificate. */
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if (DBG_X509)
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dump_cert ("crl_issuer_cert", issuer_cert);
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@ -1620,13 +1754,25 @@ finish_sig_check (ksba_crl_t crl, gcry_md_hd_t md, int algo,
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}
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/* Create an S-expression with the actual hash value. */
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s = gcry_md_algo_name (algo);
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for (i = 0; *s && i < sizeof(algoname) - 1; s++, i++)
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algoname[i] = ascii_tolower (*s);
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algoname[i] = 0;
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err = gcry_sexp_build (&s_hash, NULL, "(data(flags pkcs1)(hash %s %b))",
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algoname,
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gcry_md_get_algo_dlen (algo), gcry_md_read (md, algo));
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if (use_pss)
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{
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err = gcry_sexp_build (&s_hash, NULL,
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"(data (flags pss)"
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"(hash %s %b)"
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"(salt-length %u))",
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hash_algo_to_string (algo),
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(int)gcry_md_get_algo_dlen (algo),
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gcry_md_read (md, algo),
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saltlen);
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}
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else
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{
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err = gcry_sexp_build (&s_hash, NULL,
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"(data(flags pkcs1)(hash %s %b))",
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hash_algo_to_string (algo),
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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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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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@ -1688,6 +1834,7 @@ crl_parse_insert (ctrl_t ctrl, ksba_crl_t crl,
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ksba_cert_t crlissuer_cert = NULL;
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gcry_md_hd_t md = NULL;
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int algo = 0;
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int use_pss = 0;
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size_t n;
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(void)fname;
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@ -1710,7 +1857,7 @@ crl_parse_insert (ctrl_t ctrl, ksba_crl_t crl,
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{
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case KSBA_SR_BEGIN_ITEMS:
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{
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err = start_sig_check (crl, &md, &algo);
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err = start_sig_check (crl, &md, &algo, &use_pss);
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if (err)
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goto failure;
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@ -1847,7 +1994,7 @@ crl_parse_insert (ctrl_t ctrl, ksba_crl_t crl,
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goto failure;
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}
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err = finish_sig_check (crl, md, algo, crlissuer_cert);
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err = finish_sig_check (crl, md, algo, crlissuer_cert, use_pss);
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md = NULL; /* Closed. */
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if (err)
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{
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