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99 lines
2.8 KiB
C
99 lines
2.8 KiB
C
/* openpgp-misc.c - miscellaneous functions for OpenPGP
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* Copyright (C) 2021 g10 Code GmbH
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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 <https://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <stdlib.h>
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#include "util.h"
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#include "openpgpdefs.h"
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/*
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* Convert from OpenPGP-format with possible prefix, return
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* libgcrypt-format of the key; That is, for Ed448/X448, return key
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* with prefix removed, if any.
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*/
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gcry_mpi_t
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openpgp_to_libgcrypt (pubkey_algo_t pkalgo, const char *curve,
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gcry_mpi_t key)
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{
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unsigned int nbits = 0;
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unsigned char *buf = NULL;
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if ((pkalgo == PUBKEY_ALGO_EDDSA && !strcmp (curve, "Ed448"))
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|| (pkalgo == PUBKEY_ALGO_ECDH && !strcmp (curve, "X448")))
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buf = gcry_mpi_get_opaque (key, &nbits);
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/* Either Ed448/X448 non-prefixed or not Ed448/X448. */
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if (nbits == 0
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|| (pkalgo == PUBKEY_ALGO_EDDSA && (nbits+7)/8 == (448 + 8)/8)
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|| (pkalgo == PUBKEY_ALGO_ECDH && (nbits+7)/8 == 448/8))
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return gcry_mpi_copy (key);
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/* Ed448 or X448 prefixed. */
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if (pkalgo == PUBKEY_ALGO_EDDSA)
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return gcry_mpi_set_opaque_copy (NULL, buf+1, 8 + 448);
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else
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return gcry_mpi_set_opaque_copy (NULL, buf+1, 448);
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}
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/*
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* Convert from libgcrypt-format with no-prefix, return OpenPGP-format
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* of the key; That is, for Ed448/X448, return key with prefix added.
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*/
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gpg_error_t
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openpgp_from_libgcrypt (int algo, gcry_mpi_t *r_key)
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{
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gcry_mpi_t key_mpi;
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gcry_mpi_t a;
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unsigned char *p;
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const unsigned char *p_key;
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unsigned int nbits;
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unsigned int len;
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key_mpi = *r_key;
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*r_key = NULL;
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p_key = gcry_mpi_get_opaque (key_mpi, &nbits);
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len = (nbits+7)/8;
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if ((algo == PUBKEY_ALGO_ECDH && len != 56)
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|| (algo == PUBKEY_ALGO_EDDSA && len != 57)
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|| (algo != PUBKEY_ALGO_ECDH && algo != PUBKEY_ALGO_EDDSA))
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{
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gcry_mpi_release (key_mpi);
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return gpg_error (GPG_ERR_BAD_PUBKEY);
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}
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p = xtrymalloc (1 + len);
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if (!p)
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{
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gcry_mpi_release (key_mpi);
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return gpg_error_from_syserror ();
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}
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p[0] = 0x40;
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memcpy (p+1, p_key, len);
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a = gcry_mpi_set_opaque (NULL, p, len*8+7);
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gcry_mpi_set_flag (a, GCRYMPI_FLAG_USER2);
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*r_key = a;
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gcry_mpi_release (key_mpi);
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return 0;
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}
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