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sm: Support rsaPSS verification also for CMS signatures.
* sm/certcheck.c (gpgsm_check_cert_sig): Factor PSS parsing out to ... (extract_pss_params): new. (gpgsm_check_cms_signature): Implement PSS. -- GnuPG-bug-id: 4538
This commit is contained in:
Werner Koch
parent
8bf17eb94d
commit
24d563749f
@ -305,7 +305,7 @@ do_ocsp_request (ctrl_t ctrl, ksba_ocsp_t ocsp,
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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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/* Get the signature value now because we can call this function
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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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126
sm/certcheck.c
126
sm/certcheck.c
@ -270,6 +270,41 @@ uint_from_buffer (const void *buffer, size_t buflen)
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}
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/* Extract the hash algorithm and the salt length from the sigval. */
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static gpg_error_t
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extract_pss_params (gcry_sexp_t s_sig, int *r_algo, unsigned int *r_saltlen)
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{
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gpg_error_t err;
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gcry_buffer_t ioarray[2] = { {0}, {0} };
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err = gcry_sexp_extract_param (s_sig, "sig-val",
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"&'hash-algo''salt-length'",
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ioarray+0, ioarray+1, NULL);
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if (err)
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{
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log_error ("extracting params from PSS failed: %s\n", gpg_strerror (err));
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return err;
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}
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*r_algo = hash_algo_from_buffer (ioarray[0].data, ioarray[0].len);
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*r_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 (*r_saltlen < 20)
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{
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log_error ("length of PSS salt too short\n");
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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if (!*r_algo)
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{
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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/* log_debug ("PSS hash=%d saltlen=%u\n", *r_algo, *r_saltlen); */
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return 0;
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}
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/* Check the signature on CERT using the ISSUER-CERT. This function
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does only test the cryptographic signature and nothing else. It is
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assumed that the ISSUER_CERT is valid. */
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@ -320,35 +355,12 @@ gpgsm_check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
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if (use_pss)
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{
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/* Extract the hash algorithm and the salt length from the sigval. */
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gcry_buffer_t ioarray[2] = { {0}, {0} };
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rc = gcry_sexp_extract_param (s_sig, "sig-val",
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"&'hash-algo''salt-length'",
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ioarray+0, ioarray+1, NULL);
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rc = extract_pss_params (s_sig, &algo, &saltlen);
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if (rc)
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{
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gcry_sexp_release (s_sig);
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log_error ("extracting params from PSS failed: %s\n",
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gpg_strerror (rc));
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return rc;
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}
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algo = 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 (saltlen < 20)
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{
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log_error ("length of PSS salt too short\n");
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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if (!algo)
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{
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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/* log_debug ("PSS hash=%d saltlen=%u\n", algo, saltlen); */
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}
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@ -409,7 +421,7 @@ gpgsm_check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
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}
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else
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{
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/* RSA or DAS: Prepare the hash for verification. */
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/* RSA or DSA: Prepare the hash for verification. */
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gcry_mpi_t frame;
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rc = do_encode_md (md, algo, pk_algo_from_sexp (s_pkey),
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@ -447,10 +459,14 @@ gpgsm_check_cms_signature (ksba_cert_t cert, ksba_const_sexp_t sigval,
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{
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int rc;
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ksba_sexp_t p;
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gcry_mpi_t frame;
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gcry_sexp_t s_sig, s_hash, s_pkey;
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gcry_sexp_t s_sig, s_hash, s_pkey, l1;
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size_t n;
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const char *s;
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int i;
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int pkalgo;
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int use_pss;
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unsigned int saltlen = 0;
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if (r_pkalgo)
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*r_pkalgo = 0;
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@ -468,6 +484,42 @@ gpgsm_check_cms_signature (ksba_cert_t cert, ksba_const_sexp_t sigval,
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return rc;
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}
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/* Check whether rsaPSS is needed. This is indicated in the SIG-VAL
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* using a flag. Only if we found that flag, we extract the PSS
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* parameters for SIG-VAL. */
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use_pss = 0;
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l1 = gcry_sexp_find_token (s_sig, "flags", 0);
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if (l1)
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{
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/* Note that the flag parser assumes that the list of flags
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* contains only strings and in particular not sublist. This is
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* always the case or current libksba. */
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for (i=1; (s = gcry_sexp_nth_data (l1, i, &n)); i++)
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if (n == 3 && !memcmp (s, "pss", 3))
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{
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use_pss = 1;
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break;
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}
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gcry_sexp_release (l1);
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if (use_pss)
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{
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int algo;
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rc = extract_pss_params (s_sig, &algo, &saltlen);
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if (rc)
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{
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gcry_sexp_release (s_sig);
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return rc;
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}
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if (algo != mdalgo)
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{
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log_error ("PSS hash algo mismatch (%d/%d)\n", mdalgo, algo);
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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}
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}
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p = ksba_cert_get_public_key (cert);
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n = gcry_sexp_canon_len (p, 0, NULL, NULL);
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if (!n)
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@ -492,6 +544,25 @@ gpgsm_check_cms_signature (ksba_cert_t cert, ksba_const_sexp_t sigval,
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pkalgo = pk_algo_from_sexp (s_pkey);
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if (r_pkalgo)
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*r_pkalgo = pkalgo;
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if (use_pss)
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{
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rc = 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 (mdalgo),
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(int)gcry_md_get_algo_dlen (mdalgo),
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gcry_md_read (md, mdalgo),
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saltlen);
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if (rc)
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BUG ();
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}
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else
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{
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/* RSA or DSA: Prepare the hash for verification. */
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gcry_mpi_t frame;
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rc = do_encode_md (md, mdalgo, pkalgo,
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gcry_pk_get_nbits (s_pkey), s_pkey, &frame);
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if (rc)
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@ -504,6 +575,7 @@ gpgsm_check_cms_signature (ksba_cert_t cert, ksba_const_sexp_t sigval,
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if ( gcry_sexp_build (&s_hash, NULL, "%m", frame) )
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BUG ();
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gcry_mpi_release (frame);
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}
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rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
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if (DBG_X509)
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@ -412,8 +412,8 @@ gpgsm_verify (ctrl_t ctrl, int in_fd, int data_fd, estream_t out_fp)
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{
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log_debug ("signer %d - signature available (sigval hash=%d)",
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signer, sigval_hash_algo);
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/* log_printhex ("sigval ", sigval, */
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/* gcry_sexp_canon_len (sigval, 0, NULL, NULL)); */
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/*log_printhex(sigval, gcry_sexp_canon_len (sigval, 0, NULL, NULL),*/
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/* "sigval "); */
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}
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if (!sigval_hash_algo)
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sigval_hash_algo = algo; /* Fallback used e.g. with old libksba. */
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