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371 lines
10 KiB
C
371 lines
10 KiB
C
/* pkglue.c - public key operations glue code
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* Copyright (C) 2000, 2003, 2010 Free Software Foundation, Inc.
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* Copyright (C) 2014 Werner Koch
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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 3 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, see <http://www.gnu.org/licenses/>.
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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 "gpg.h"
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#include "util.h"
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#include "pkglue.h"
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#include "main.h"
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#include "options.h"
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/* FIXME: Better change the function name because mpi_ is used by
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gcrypt macros. */
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gcry_mpi_t
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get_mpi_from_sexp (gcry_sexp_t sexp, const char *item, int mpifmt)
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{
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gcry_sexp_t list;
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gcry_mpi_t data;
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list = gcry_sexp_find_token (sexp, item, 0);
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log_assert (list);
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data = gcry_sexp_nth_mpi (list, 1, mpifmt);
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log_assert (data);
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gcry_sexp_release (list);
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return data;
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}
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/****************
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* Emulate our old PK interface here - sometime in the future we might
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* change the internal design to directly fit to libgcrypt.
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*/
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int
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pk_verify (pubkey_algo_t pkalgo, gcry_mpi_t hash,
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gcry_mpi_t *data, gcry_mpi_t *pkey)
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{
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gcry_sexp_t s_sig, s_hash, s_pkey;
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int rc;
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/* Make a sexp from pkey. */
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if (pkalgo == PUBKEY_ALGO_DSA)
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{
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rc = gcry_sexp_build (&s_pkey, NULL,
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"(public-key(dsa(p%m)(q%m)(g%m)(y%m)))",
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pkey[0], pkey[1], pkey[2], pkey[3]);
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}
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else if (pkalgo == PUBKEY_ALGO_ELGAMAL_E || pkalgo == PUBKEY_ALGO_ELGAMAL)
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{
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rc = gcry_sexp_build (&s_pkey, NULL,
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"(public-key(elg(p%m)(g%m)(y%m)))",
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pkey[0], pkey[1], pkey[2]);
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}
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else if (pkalgo == PUBKEY_ALGO_RSA || pkalgo == PUBKEY_ALGO_RSA_S)
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{
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rc = gcry_sexp_build (&s_pkey, NULL,
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"(public-key(rsa(n%m)(e%m)))", pkey[0], pkey[1]);
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}
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else if (pkalgo == PUBKEY_ALGO_ECDSA)
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{
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char *curve = openpgp_oid_to_str (pkey[0]);
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if (!curve)
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rc = gpg_error_from_syserror ();
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else
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{
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rc = gcry_sexp_build (&s_pkey, NULL,
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"(public-key(ecdsa(curve %s)(q%m)))",
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curve, pkey[1]);
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xfree (curve);
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}
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}
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else if (pkalgo == PUBKEY_ALGO_EDDSA)
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{
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char *curve = openpgp_oid_to_str (pkey[0]);
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if (!curve)
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rc = gpg_error_from_syserror ();
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else
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{
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rc = gcry_sexp_build (&s_pkey, NULL,
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"(public-key(ecc(curve %s)"
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"(flags eddsa)(q%m)))",
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curve, pkey[1]);
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xfree (curve);
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}
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}
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else
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return GPG_ERR_PUBKEY_ALGO;
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if (rc)
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BUG (); /* gcry_sexp_build should never fail. */
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/* Put hash into a S-Exp s_hash. */
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if (pkalgo == PUBKEY_ALGO_EDDSA)
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{
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if (gcry_sexp_build (&s_hash, NULL,
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"(data(flags eddsa)(hash-algo sha512)(value %m))",
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hash))
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BUG (); /* gcry_sexp_build should never fail. */
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}
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else
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{
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if (gcry_sexp_build (&s_hash, NULL, "%m", hash))
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BUG (); /* gcry_sexp_build should never fail. */
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}
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/* Put data into a S-Exp s_sig. */
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s_sig = NULL;
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if (pkalgo == PUBKEY_ALGO_DSA)
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{
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if (!data[0] || !data[1])
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rc = gpg_error (GPG_ERR_BAD_MPI);
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else
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rc = gcry_sexp_build (&s_sig, NULL,
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"(sig-val(dsa(r%m)(s%m)))", data[0], data[1]);
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}
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else if (pkalgo == PUBKEY_ALGO_ECDSA)
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{
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if (!data[0] || !data[1])
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rc = gpg_error (GPG_ERR_BAD_MPI);
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else
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rc = gcry_sexp_build (&s_sig, NULL,
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"(sig-val(ecdsa(r%m)(s%m)))", data[0], data[1]);
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}
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else if (pkalgo == PUBKEY_ALGO_EDDSA)
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{
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if (!data[0] || !data[1])
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rc = gpg_error (GPG_ERR_BAD_MPI);
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else
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rc = gcry_sexp_build (&s_sig, NULL,
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"(sig-val(eddsa(r%M)(s%M)))", data[0], data[1]);
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}
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else if (pkalgo == PUBKEY_ALGO_ELGAMAL || pkalgo == PUBKEY_ALGO_ELGAMAL_E)
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{
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if (!data[0] || !data[1])
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rc = gpg_error (GPG_ERR_BAD_MPI);
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else
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rc = gcry_sexp_build (&s_sig, NULL,
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"(sig-val(elg(r%m)(s%m)))", data[0], data[1]);
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}
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else if (pkalgo == PUBKEY_ALGO_RSA || pkalgo == PUBKEY_ALGO_RSA_S)
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{
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if (!data[0])
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rc = gpg_error (GPG_ERR_BAD_MPI);
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else
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rc = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", data[0]);
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}
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else
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BUG ();
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if (!rc)
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rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
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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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/****************
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* Emulate our old PK interface here - sometime in the future we might
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* change the internal design to directly fit to libgcrypt.
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* PK is only required to compute the fingerprint for ECDH.
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*/
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int
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pk_encrypt (pubkey_algo_t algo, gcry_mpi_t *resarr, gcry_mpi_t data,
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PKT_public_key *pk, gcry_mpi_t *pkey)
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{
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gcry_sexp_t s_ciph = NULL;
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gcry_sexp_t s_data = NULL;
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gcry_sexp_t s_pkey = NULL;
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int rc;
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/* Make a sexp from pkey. */
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if (algo == PUBKEY_ALGO_ELGAMAL || algo == PUBKEY_ALGO_ELGAMAL_E)
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{
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rc = gcry_sexp_build (&s_pkey, NULL,
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"(public-key(elg(p%m)(g%m)(y%m)))",
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pkey[0], pkey[1], pkey[2]);
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/* Put DATA into a simplified S-expression. */
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if (!rc)
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rc = gcry_sexp_build (&s_data, NULL, "%m", data);
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}
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else if (algo == PUBKEY_ALGO_RSA || algo == PUBKEY_ALGO_RSA_E)
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{
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rc = gcry_sexp_build (&s_pkey, NULL,
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"(public-key(rsa(n%m)(e%m)))",
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pkey[0], pkey[1]);
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/* Put DATA into a simplified S-expression. */
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if (!rc)
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rc = gcry_sexp_build (&s_data, NULL, "%m", data);
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}
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else if (algo == PUBKEY_ALGO_ECDH)
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{
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gcry_mpi_t k;
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rc = pk_ecdh_generate_ephemeral_key (pkey, &k);
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if (!rc)
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{
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char *curve;
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curve = openpgp_oid_to_str (pkey[0]);
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if (!curve)
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rc = gpg_error_from_syserror ();
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else
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{
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int with_djb_tweak_flag = openpgp_oid_is_crv25519 (pkey[0]);
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/* Now use the ephemeral secret to compute the shared point. */
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rc = gcry_sexp_build (&s_pkey, NULL,
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with_djb_tweak_flag ?
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"(public-key(ecdh(curve%s)(flags djb-tweak)(q%m)))"
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: "(public-key(ecdh(curve%s)(q%m)))",
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curve, pkey[1]);
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xfree (curve);
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/* Put K into a simplified S-expression. */
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if (!rc)
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rc = gcry_sexp_build (&s_data, NULL, "%m", k);
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}
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gcry_mpi_release (k);
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}
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}
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else
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rc = gpg_error (GPG_ERR_PUBKEY_ALGO);
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/* Pass it to libgcrypt. */
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if (!rc)
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rc = gcry_pk_encrypt (&s_ciph, s_data, s_pkey);
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gcry_sexp_release (s_data);
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gcry_sexp_release (s_pkey);
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if (rc)
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;
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else if (algo == PUBKEY_ALGO_ECDH)
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{
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gcry_mpi_t shared, public, result;
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byte fp[MAX_FINGERPRINT_LEN];
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size_t fpn;
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/* Get the shared point and the ephemeral public key. */
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shared = get_mpi_from_sexp (s_ciph, "s", GCRYMPI_FMT_USG);
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public = get_mpi_from_sexp (s_ciph, "e", GCRYMPI_FMT_USG);
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gcry_sexp_release (s_ciph);
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s_ciph = NULL;
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if (DBG_CRYPTO)
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{
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log_debug ("ECDH ephemeral key:");
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gcry_mpi_dump (public);
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log_printf ("\n");
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}
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result = NULL;
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fingerprint_from_pk (pk, fp, &fpn);
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if (fpn != 20)
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rc = gpg_error (GPG_ERR_INV_LENGTH);
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else
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rc = pk_ecdh_encrypt_with_shared_point (1 /*=encrypton*/, shared,
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fp, data, pkey, &result);
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gcry_mpi_release (shared);
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if (!rc)
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{
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resarr[0] = public;
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resarr[1] = result;
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}
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else
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{
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gcry_mpi_release (public);
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gcry_mpi_release (result);
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}
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}
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else /* Elgamal or RSA case. */
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{ /* Fixme: Add better error handling or make gnupg use
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S-expressions directly. */
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resarr[0] = get_mpi_from_sexp (s_ciph, "a", GCRYMPI_FMT_USG);
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if (!is_RSA (algo))
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resarr[1] = get_mpi_from_sexp (s_ciph, "b", GCRYMPI_FMT_USG);
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}
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gcry_sexp_release (s_ciph);
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return rc;
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}
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/* Check whether SKEY is a suitable secret key. */
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int
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pk_check_secret_key (pubkey_algo_t pkalgo, gcry_mpi_t *skey)
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{
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gcry_sexp_t s_skey;
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int rc;
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if (pkalgo == PUBKEY_ALGO_DSA)
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{
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rc = gcry_sexp_build (&s_skey, NULL,
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"(private-key(dsa(p%m)(q%m)(g%m)(y%m)(x%m)))",
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skey[0], skey[1], skey[2], skey[3], skey[4]);
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}
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else if (pkalgo == PUBKEY_ALGO_ELGAMAL || pkalgo == PUBKEY_ALGO_ELGAMAL_E)
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{
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rc = gcry_sexp_build (&s_skey, NULL,
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"(private-key(elg(p%m)(g%m)(y%m)(x%m)))",
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skey[0], skey[1], skey[2], skey[3]);
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}
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else if (is_RSA (pkalgo))
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{
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rc = gcry_sexp_build (&s_skey, NULL,
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"(private-key(rsa(n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))",
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skey[0], skey[1], skey[2], skey[3], skey[4],
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skey[5]);
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}
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else if (pkalgo == PUBKEY_ALGO_ECDSA || pkalgo == PUBKEY_ALGO_ECDH)
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{
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char *curve = openpgp_oid_to_str (skey[0]);
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if (!curve)
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rc = gpg_error_from_syserror ();
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else
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{
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rc = gcry_sexp_build (&s_skey, NULL,
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"(private-key(ecc(curve%s)(q%m)(d%m)))",
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curve, skey[1], skey[2]);
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xfree (curve);
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}
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}
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else if (pkalgo == PUBKEY_ALGO_EDDSA)
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{
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char *curve = openpgp_oid_to_str (skey[0]);
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if (!curve)
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rc = gpg_error_from_syserror ();
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else
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{
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rc = gcry_sexp_build (&s_skey, NULL,
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"(private-key(ecc(curve %s)"
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"(flags eddsa)(q%m)(d%m)))",
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curve, skey[1], skey[2]);
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xfree (curve);
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}
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}
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else
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return GPG_ERR_PUBKEY_ALGO;
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if (!rc)
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{
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rc = gcry_pk_testkey (s_skey);
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gcry_sexp_release (s_skey);
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}
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return rc;
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}
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