mirror of git://git.gnupg.org/gnupg.git
301 lines
7.2 KiB
C
301 lines
7.2 KiB
C
/* certcheck.c - check one certificate
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* Copyright (C) 2001, 2003 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <time.h>
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#include <assert.h>
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#include "gpgsm.h"
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#include <gcrypt.h>
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#include <ksba.h>
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#include "keydb.h"
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#include "i18n.h"
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static int
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do_encode_md (gcry_md_hd_t md, int algo, unsigned int nbits,
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gcry_mpi_t *r_val)
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{
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int nframe = (nbits+7) / 8;
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byte *frame;
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int i, n;
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byte asn[100];
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size_t asnlen;
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size_t len;
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asnlen = DIM(asn);
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if (gcry_md_algo_info (algo, GCRYCTL_GET_ASNOID, asn, &asnlen))
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{
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log_error ("No object identifier for algo %d\n", algo);
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return gpg_error (GPG_ERR_INTERNAL);
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}
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len = gcry_md_get_algo_dlen (algo);
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if ( len + asnlen + 4 > nframe )
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{
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log_error ("can't encode a %d bit MD into a %d bits frame\n",
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(int)(len*8), (int)nbits);
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return gpg_error (GPG_ERR_INTERNAL);
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}
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/* We encode the MD in this way:
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*
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* 0 A PAD(n bytes) 0 ASN(asnlen bytes) MD(len bytes)
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*
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* PAD consists of FF bytes.
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*/
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frame = xtrymalloc (nframe);
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if (!frame)
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return OUT_OF_CORE (errno);
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n = 0;
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frame[n++] = 0;
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frame[n++] = 1; /* block type */
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i = nframe - len - asnlen -3 ;
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assert ( i > 1 );
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memset ( frame+n, 0xff, i ); n += i;
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frame[n++] = 0;
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memcpy ( frame+n, asn, asnlen ); n += asnlen;
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memcpy ( frame+n, gcry_md_read(md, algo), len ); n += len;
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assert ( n == nframe );
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if (DBG_X509)
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{
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int j;
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log_debug ("encoded hash:");
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for (j=0; j < nframe; j++)
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log_printf (" %02X", frame[j]);
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log_printf ("\n");
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}
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gcry_mpi_scan (r_val, GCRYMPI_FMT_USG, frame, &nframe);
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xfree (frame);
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return 0;
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}
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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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int
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gpgsm_check_cert_sig (KsbaCert issuer_cert, KsbaCert cert)
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{
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const char *algoid;
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gcry_md_hd_t md;
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int rc, algo;
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gcry_mpi_t frame;
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KsbaSexp p;
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size_t n;
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gcry_sexp_t s_sig, s_hash, s_pkey;
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algo = gcry_md_map_name ( (algoid=ksba_cert_get_digest_algo (cert)));
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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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return gpg_error (GPG_ERR_GENERAL);
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}
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rc = gcry_md_open (&md, algo, 0);
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if (rc)
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{
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log_error ("md_open failed: %s\n", gpg_strerror (rc));
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return rc;
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}
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if (DBG_HASHING)
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gcry_md_start_debug (md, "hash.cert");
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rc = ksba_cert_hash (cert, 1, HASH_FNC, md);
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if (rc)
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{
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log_error ("ksba_cert_hash failed: %s\n", ksba_strerror (rc));
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gcry_md_close (md);
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return map_ksba_err (rc);
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}
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gcry_md_final (md);
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p = ksba_cert_get_sig_val (cert);
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n = gcry_sexp_canon_len (p, 0, NULL, NULL);
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if (!n)
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{
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log_error ("libksba did not return a proper S-Exp\n");
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gcry_md_close (md);
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ksba_free (p);
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return gpg_error (GPG_ERR_BUG);
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}
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if (DBG_X509)
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{
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int j;
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log_debug ("signature value:");
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for (j=0; j < n; j++)
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log_printf (" %02X", p[j]);
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log_printf ("\n");
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}
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rc = gcry_sexp_sscan ( &s_sig, NULL, p, n);
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ksba_free (p);
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if (rc)
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{
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log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
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gcry_md_close (md);
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return rc;
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}
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p = ksba_cert_get_public_key (issuer_cert);
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n = gcry_sexp_canon_len (p, 0, NULL, NULL);
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if (!n)
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{
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log_error ("libksba did not return a proper S-Exp\n");
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gcry_md_close (md);
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ksba_free (p);
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_BUG);
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}
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rc = gcry_sexp_sscan ( &s_pkey, NULL, p, n);
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ksba_free (p);
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if (rc)
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{
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log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
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gcry_md_close (md);
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gcry_sexp_release (s_sig);
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return rc;
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}
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rc = do_encode_md (md, algo, gcry_pk_get_nbits (s_pkey), &frame);
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if (rc)
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{
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gcry_md_close (md);
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gcry_sexp_release (s_sig);
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gcry_sexp_release (s_pkey);
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return rc;
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}
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/* put hash into the S-Exp s_hash */
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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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rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
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if (DBG_CRYPTO)
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log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
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gcry_md_close (md);
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gcry_sexp_release (s_sig);
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gcry_sexp_release (s_hash);
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gcry_sexp_release (s_pkey);
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return rc;
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}
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int
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gpgsm_check_cms_signature (KsbaCert cert, KsbaConstSexp sigval,
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gcry_md_hd_t md, int algo)
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{
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int rc;
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KsbaSexp 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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size_t n;
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n = gcry_sexp_canon_len (sigval, 0, NULL, NULL);
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if (!n)
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{
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log_error ("libksba did not return a proper S-Exp\n");
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return gpg_error (GPG_ERR_BUG);
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}
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rc = gcry_sexp_sscan (&s_sig, NULL, sigval, n);
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if (rc)
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{
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log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
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return rc;
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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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{
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log_error ("libksba did not return a proper S-Exp\n");
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ksba_free (p);
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_BUG);
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}
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if (DBG_X509)
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log_printhex ("public key: ", p, n);
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rc = gcry_sexp_sscan ( &s_pkey, NULL, p, n);
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ksba_free (p);
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if (rc)
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{
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log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
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gcry_sexp_release (s_sig);
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return rc;
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}
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rc = do_encode_md (md, algo, gcry_pk_get_nbits (s_pkey), &frame);
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if (rc)
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{
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gcry_sexp_release (s_sig);
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gcry_sexp_release (s_pkey);
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return rc;
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}
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/* put hash into the S-Exp s_hash */
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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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rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
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if (DBG_CRYPTO)
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log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
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gcry_sexp_release (s_sig);
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gcry_sexp_release (s_hash);
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gcry_sexp_release (s_pkey);
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return rc;
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}
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int
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gpgsm_create_cms_signature (KsbaCert cert, gcry_md_hd_t md, int mdalgo,
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char **r_sigval)
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{
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int rc;
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char *grip;
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size_t siglen;
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grip = gpgsm_get_keygrip_hexstring (cert);
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if (!grip)
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return gpg_error (GPG_ERR_BAD_CERT);
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rc = gpgsm_agent_pksign (grip, gcry_md_read(md, mdalgo),
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gcry_md_get_algo_dlen (mdalgo), mdalgo,
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r_sigval, &siglen);
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xfree (grip);
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return rc;
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}
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