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/* pkglue.c - public key operations glue code
* Copyright (C) 2000, 2003, 2010 Free Software Foundation, Inc.
* Copyright (C) 2014 Werner Koch
* Copyright (C) 2024 g10 Code GmbH.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
* SPDX-License-Identifier: GPL-3.0-or-later
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "gpg.h"
#include "../common/util.h"
#include "pkglue.h"
#include "main.h"
#include "options.h"
/* FIXME: Better change the function name because mpi_ is used by
gcrypt macros. */
gcry_mpi_t
get_mpi_from_sexp (gcry_sexp_t sexp, const char *item, int mpifmt)
{
gcry_sexp_t list;
gcry_mpi_t data;
list = gcry_sexp_find_token (sexp, item, 0);
log_assert (list);
data = gcry_sexp_nth_mpi (list, 1, mpifmt);
log_assert (data);
gcry_sexp_release (list);
return data;
}
/*
* SOS (Simply, Octet String) is an attempt to handle opaque octet
* string in OpenPGP, where well-formed MPI cannot represent octet
* string with leading zero octets.
*
* To retain maximum compatibility to existing MPI handling, SOS
* has same structure, but allows leading zero octets. When there
* is no leading zero octets, SOS representation is as same as MPI one.
* With leading zero octets, NBITS is 8*(length of octets), regardless
* of leading zero bits.
*/
/* Extract SOS representation from SEXP for PARAM, return the result
* in R_SOS. It is represented by opaque MPI with GCRYMPI_FLAG_USER2
* flag. */
gpg_error_t
sexp_extract_param_sos (gcry_sexp_t sexp, const char *param, gcry_mpi_t *r_sos)
{
gpg_error_t err;
gcry_sexp_t l2 = gcry_sexp_find_token (sexp, param, 0);
*r_sos = NULL;
if (!l2)
err = gpg_error (GPG_ERR_NO_OBJ);
else
{
size_t buflen;
void *p0 = gcry_sexp_nth_buffer (l2, 1, &buflen);
if (!p0)
err = gpg_error_from_syserror ();
else
{
gcry_mpi_t sos;
unsigned int nbits = buflen*8;
unsigned char *p = p0;
if (*p && nbits >= 8 && !(*p & 0x80))
if (--nbits >= 7 && !(*p & 0x40))
if (--nbits >= 6 && !(*p & 0x20))
if (--nbits >= 5 && !(*p & 0x10))
if (--nbits >= 4 && !(*p & 0x08))
if (--nbits >= 3 && !(*p & 0x04))
if (--nbits >= 2 && !(*p & 0x02))
if (--nbits >= 1 && !(*p & 0x01))
--nbits;
sos = gcry_mpi_set_opaque (NULL, p0, nbits);
if (sos)
{
gcry_mpi_set_flag (sos, GCRYMPI_FLAG_USER2);
*r_sos = sos;
err = 0;
}
else
err = gpg_error_from_syserror ();
}
gcry_sexp_release (l2);
}
return err;
}
/* "No leading zero octets" (nlz) version of the function above.
*
* This routine is used for backward compatibility to existing
* implementation with the weird handling of little endian integer
* representation with leading zero octets. For the sake of
* "well-fomed" MPI, which is designed for big endian integer, leading
* zero octets are removed when output, and they are recovered at
* input.
*
* Extract SOS representation from SEXP for PARAM, removing leading
* zeros, return the result in R_SOS. */
gpg_error_t
sexp_extract_param_sos_nlz (gcry_sexp_t sexp, const char *param,
gcry_mpi_t *r_sos)
{
gpg_error_t err;
gcry_sexp_t l2 = gcry_sexp_find_token (sexp, param, 0);
*r_sos = NULL;
if (!l2)
err = gpg_error (GPG_ERR_NO_OBJ);
else
{
size_t buflen;
const void *p0 = gcry_sexp_nth_data (l2, 1, &buflen);
if (!p0)
err = gpg_error_from_syserror ();
else
{
gcry_mpi_t sos;
unsigned int nbits = buflen*8;
const unsigned char *p = p0;
/* Strip leading zero bits. */
for (; nbits >= 8 && !*p; p++, nbits -= 8)
;
if (nbits >= 8 && !(*p & 0x80))
if (--nbits >= 7 && !(*p & 0x40))
if (--nbits >= 6 && !(*p & 0x20))
if (--nbits >= 5 && !(*p & 0x10))
if (--nbits >= 4 && !(*p & 0x08))
if (--nbits >= 3 && !(*p & 0x04))
if (--nbits >= 2 && !(*p & 0x02))
if (--nbits >= 1 && !(*p & 0x01))
--nbits;
sos = gcry_mpi_set_opaque_copy (NULL, p, nbits);
if (sos)
{
gcry_mpi_set_flag (sos, GCRYMPI_FLAG_USER2);
*r_sos = sos;
err = 0;
}
else
err = gpg_error_from_syserror ();
}
gcry_sexp_release (l2);
}
return err;
}
/****************
* Emulate our old PK interface here - sometime in the future we might
* change the internal design to directly fit to libgcrypt.
*/
int
pk_verify (pubkey_algo_t pkalgo, gcry_mpi_t hash,
gcry_mpi_t *data, gcry_mpi_t *pkey)
{
gcry_sexp_t s_sig, s_hash, s_pkey;
int rc;
/* Make a sexp from pkey. */
if (pkalgo == PUBKEY_ALGO_DSA)
{
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(dsa(p%m)(q%m)(g%m)(y%m)))",
pkey[0], pkey[1], pkey[2], pkey[3]);
}
else if (pkalgo == PUBKEY_ALGO_ELGAMAL_E || pkalgo == PUBKEY_ALGO_ELGAMAL)
{
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(elg(p%m)(g%m)(y%m)))",
pkey[0], pkey[1], pkey[2]);
}
else if (pkalgo == PUBKEY_ALGO_RSA || pkalgo == PUBKEY_ALGO_RSA_S)
{
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(rsa(n%m)(e%m)))", pkey[0], pkey[1]);
}
else if (pkalgo == PUBKEY_ALGO_ECDSA)
{
char *curve = openpgp_oid_to_str (pkey[0]);
if (!curve)
rc = gpg_error_from_syserror ();
else
{
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(ecdsa(curve %s)(q%m)))",
curve, pkey[1]);
xfree (curve);
}
}
else if (pkalgo == PUBKEY_ALGO_EDDSA)
{
char *curve = openpgp_oid_to_str (pkey[0]);
if (!curve)
rc = gpg_error_from_syserror ();
else
{
const char *fmt;
if (openpgp_oid_is_ed25519 (pkey[0]))
fmt = "(public-key(ecc(curve %s)(flags eddsa)(q%m)))";
else
fmt = "(public-key(ecc(curve %s)(q%m)))";
rc = gcry_sexp_build (&s_pkey, NULL, fmt, curve, pkey[1]);
xfree (curve);
}
}
else
return GPG_ERR_PUBKEY_ALGO;
if (rc)
BUG (); /* gcry_sexp_build should never fail. */
/* Put hash into a S-Exp s_hash. */
if (pkalgo == PUBKEY_ALGO_EDDSA)
{
const char *fmt;
if (openpgp_oid_is_ed25519 (pkey[0]))
fmt = "(data(flags eddsa)(hash-algo sha512)(value %m))";
else
fmt = "(data(value %m))";
if (gcry_sexp_build (&s_hash, NULL, fmt, hash))
BUG (); /* gcry_sexp_build should never fail. */
}
else
{
if (gcry_sexp_build (&s_hash, NULL, "%m", hash))
BUG (); /* gcry_sexp_build should never fail. */
}
/* Put data into a S-Exp s_sig. */
s_sig = NULL;
if (pkalgo == PUBKEY_ALGO_DSA)
{
if (!data[0] || !data[1])
rc = gpg_error (GPG_ERR_BAD_MPI);
else
rc = gcry_sexp_build (&s_sig, NULL,
"(sig-val(dsa(r%m)(s%m)))", data[0], data[1]);
}
else if (pkalgo == PUBKEY_ALGO_ECDSA)
{
if (!data[0] || !data[1])
rc = gpg_error (GPG_ERR_BAD_MPI);
else
rc = gcry_sexp_build (&s_sig, NULL,
"(sig-val(ecdsa(r%m)(s%m)))", data[0], data[1]);
}
else if (pkalgo == PUBKEY_ALGO_EDDSA)
{
gcry_mpi_t r = data[0];
gcry_mpi_t s = data[1];
if (openpgp_oid_is_ed25519 (pkey[0]))
{
size_t rlen, slen, n; /* (bytes) */
char buf[64];
unsigned int nbits;
unsigned int neededfixedlen = 256 / 8;
log_assert (neededfixedlen <= sizeof buf);
if (!r || !s)
rc = gpg_error (GPG_ERR_BAD_MPI);
else if ((rlen = (gcry_mpi_get_nbits (r)+7)/8) > neededfixedlen || !rlen)
rc = gpg_error (GPG_ERR_BAD_MPI);
else if ((slen = (gcry_mpi_get_nbits (s)+7)/8) > neededfixedlen || !slen)
rc = gpg_error (GPG_ERR_BAD_MPI);
else
{
r = gcry_mpi_copy (r);
s = gcry_mpi_copy (s);
if (!r || !s)
{
rc = gpg_error_from_syserror ();
goto leave;
}
/* We need to fixup the length in case of leading zeroes.
* OpenPGP does not allow leading zeroes and the parser for
* the signature packet has no information on the used curve,
* thus we need to do it here. We won't do it for opaque
* MPIs under the assumption that they are known to be fine;
* we won't see them here anyway but the check is anyway
* required. Fixme: A nifty feature for gcry_sexp_build
* would be a format to left pad the value (e.g. "%*M"). */
rc = 0;
if (rlen < neededfixedlen
&& !gcry_mpi_get_flag (r, GCRYMPI_FLAG_OPAQUE)
&& !(rc=gcry_mpi_print (GCRYMPI_FMT_USG,
buf, sizeof buf, &n, r)))
{
log_assert (n < neededfixedlen);
memmove (buf + (neededfixedlen - n), buf, n);
memset (buf, 0, neededfixedlen - n);
gcry_mpi_set_opaque_copy (r, buf, neededfixedlen * 8);
}
else if (rlen < neededfixedlen
&& gcry_mpi_get_flag (r, GCRYMPI_FLAG_OPAQUE))
{
const unsigned char *p;
p = gcry_mpi_get_opaque (r, &nbits);
n = (nbits+7)/8;
memcpy (buf + (neededfixedlen - n), p, n);
memset (buf, 0, neededfixedlen - n);
gcry_mpi_set_opaque_copy (r, buf, neededfixedlen * 8);
}
if (rc)
;
else if (slen < neededfixedlen
&& !gcry_mpi_get_flag (s, GCRYMPI_FLAG_OPAQUE)
&& !(rc=gcry_mpi_print (GCRYMPI_FMT_USG,
buf, sizeof buf, &n, s)))
{
log_assert (n < neededfixedlen);
memmove (buf + (neededfixedlen - n), buf, n);
memset (buf, 0, neededfixedlen - n);
gcry_mpi_set_opaque_copy (s, buf, neededfixedlen * 8);
}
else if (slen < neededfixedlen
&& gcry_mpi_get_flag (s, GCRYMPI_FLAG_OPAQUE))
{
const unsigned char *p;
p = gcry_mpi_get_opaque (s, &nbits);
n = (nbits+7)/8;
memcpy (buf + (neededfixedlen - n), p, n);
memset (buf, 0, neededfixedlen - n);
gcry_mpi_set_opaque_copy (s, buf, neededfixedlen * 8);
}
}
}
else
rc = 0;
if (!rc)
rc = gcry_sexp_build (&s_sig, NULL,
"(sig-val(eddsa(r%M)(s%M)))", r, s);
if (r != data[0])
gcry_mpi_release (r);
if (s != data[1])
gcry_mpi_release (s);
}
else if (pkalgo == PUBKEY_ALGO_ELGAMAL || pkalgo == PUBKEY_ALGO_ELGAMAL_E)
{
if (!data[0] || !data[1])
rc = gpg_error (GPG_ERR_BAD_MPI);
else
rc = gcry_sexp_build (&s_sig, NULL,
"(sig-val(elg(r%m)(s%m)))", data[0], data[1]);
}
else if (pkalgo == PUBKEY_ALGO_RSA || pkalgo == PUBKEY_ALGO_RSA_S)
{
if (!data[0])
rc = gpg_error (GPG_ERR_BAD_MPI);
else
rc = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", data[0]);
}
else
BUG ();
if (!rc)
rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
leave:
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
return rc;
}
#if GCRY_KEM_MLKEM1024_ENCAPS_LEN < GCRY_KEM_MLKEM768_ENCAPS_LEN \
|| GCRY_KEM_MLKEM1024_SHARED_LEN < GCRY_KEM_MLKEM768_SHARED_LEN
# error Bad Kyber constants in Libgcrypt
#endif
/* Core of the encryption for KEM algorithms. See pk_decrypt for a
* description of the arguments. */
static gpg_error_t
do_encrypt_kem (PKT_public_key *pk, gcry_mpi_t data, int seskey_algo,
gcry_mpi_t *resarr)
{
gpg_error_t err;
int i;
unsigned int nbits, n;
gcry_sexp_t s_data = NULL;
gcry_cipher_hd_t hd = NULL;
char *ecc_oid = NULL;
const char *curve;
const struct gnupg_ecc_params *ecc;
enum gcry_kem_algos kyber_algo;
const unsigned char *ecc_pubkey;
size_t ecc_pubkey_len;
const unsigned char *kyber_pubkey;
size_t kyber_pubkey_len;
const unsigned char *seskey;
size_t seskey_len;
unsigned char *enc_seskey = NULL;
size_t enc_seskey_len;
int ecc_hash_algo;
unsigned char ecc_ct[ECC_POINT_LEN_MAX];
unsigned char ecc_ecdh[ECC_POINT_LEN_MAX];
unsigned char ecc_ss[ECC_HASH_LEN_MAX];
size_t ecc_ct_len, ecc_ecdh_len, ecc_ss_len;
unsigned char kyber_ct[GCRY_KEM_MLKEM1024_ENCAPS_LEN];
unsigned char kyber_ss[GCRY_KEM_MLKEM1024_SHARED_LEN];
size_t kyber_ct_len, kyber_ss_len;
char fixedinfo[1+MAX_FINGERPRINT_LEN];
int fixedlen;
unsigned char kek[32]; /* AES-256 is mandatory. */
size_t kek_len = 32;
/* For later error checking we make sure the array is cleared. */
resarr[0] = resarr[1] = resarr[2] = NULL;
/* As of now we use KEM only for the combined Kyber and thus a
* second public key is expected. Right now we take the keys
* directly from the PK->data elements. */
ecc_oid = openpgp_oid_to_str (pk->pkey[0]);
if (!ecc_oid)
{
err = gpg_error_from_syserror ();
log_error ("%s: error getting OID for ECC key\n", __func__);
goto leave;
}
curve = openpgp_oid_to_curve (ecc_oid, 1);
if (!curve)
{
err = gpg_error (GPG_ERR_INV_DATA);
log_error ("%s: error getting curve for ECC key\n", __func__);
goto leave;
}
ecc = gnupg_get_ecc_params (curve);
if (!ecc)
{
if (opt.verbose)
log_info ("%s: ECC curve %s not supported\n", __func__, curve);
err = gpg_error (GPG_ERR_INV_DATA);
goto leave;
}
ecc_ct_len = ecc_ecdh_len = ecc->point_len;
ecc_hash_algo = ecc->hash_algo;
ecc_ss_len = gcry_md_get_algo_dlen (ecc_hash_algo);
ecc_pubkey = gcry_mpi_get_opaque (pk->pkey[1], &nbits);
ecc_pubkey_len = (nbits+7)/8;
if (ecc_pubkey_len != ecc->pubkey_len)
{
if (ecc->kem_algo == GCRY_KEM_RAW_X25519
&& ecc_pubkey_len == ecc->pubkey_len - 1)
/* For Curve25519, we also accept no prefix in the point
* representation. */
;
else
{
if (opt.verbose)
log_info ("%s: ECC public key length invalid (%zu)\n",
__func__, ecc_pubkey_len);
err = gpg_error (GPG_ERR_INV_DATA);
goto leave;
}
}
if (ecc->kem_algo == GCRY_KEM_RAW_X25519)
{
if (!strcmp (ecc_oid, "1.3.6.1.4.1.3029.1.5.1"))
log_info ("Warning: "
"legacy OID for cv25519 accepted during development\n");
/* Optional prefix handling */
if (ecc_pubkey_len == 33 && *ecc_pubkey == 0x40)
{
ecc_pubkey++; /* Remove the 0x40 prefix. */
ecc_pubkey_len--;
}
}
if (DBG_CRYPTO)
{
log_debug ("ECC curve: %s\n", ecc_oid);
log_printhex (ecc_pubkey, ecc_pubkey_len, "ECC pubkey:");
}
err = gcry_kem_encap (ecc->kem_algo,
ecc_pubkey, ecc_pubkey_len,
ecc_ct, ecc_ct_len,
ecc_ecdh, ecc_ecdh_len,
NULL, 0);
if (err)
{
if (opt.verbose)
log_info ("%s: gcry_kem_encap for ECC (%s) failed\n",
__func__, ecc_oid);
goto leave;
}
if (DBG_CRYPTO)
{
log_printhex (ecc_ct, ecc_ct_len, "ECC ephem:");
log_printhex (ecc_ecdh, ecc_ecdh_len, "ECC ecdh:");
}
err = gnupg_ecc_kem_kdf (ecc_ss, ecc_ss_len,
ecc_hash_algo,
ecc_ecdh, ecc_ecdh_len,
ecc_ct, ecc_ct_len,
ecc_pubkey, ecc_pubkey_len, NULL, 0);
if (err)
{
if (opt.verbose)
log_info ("%s: kdf for ECC failed\n", __func__);
goto leave;
}
if (DBG_CRYPTO)
log_printhex (ecc_ss, ecc_ss_len, "ECC shared:");
kyber_pubkey = gcry_mpi_get_opaque (pk->pkey[2], &nbits);
kyber_pubkey_len = (nbits+7)/8;
if (kyber_pubkey_len == GCRY_KEM_MLKEM768_PUBKEY_LEN)
{
kyber_algo = GCRY_KEM_MLKEM768;
kyber_ct_len = GCRY_KEM_MLKEM768_ENCAPS_LEN;
kyber_ss_len = GCRY_KEM_MLKEM768_SHARED_LEN;
}
else if (kyber_pubkey_len == GCRY_KEM_MLKEM1024_PUBKEY_LEN)
{
kyber_algo = GCRY_KEM_MLKEM1024;
kyber_ct_len = GCRY_KEM_MLKEM1024_ENCAPS_LEN;
kyber_ss_len = GCRY_KEM_MLKEM1024_SHARED_LEN;
}
else
{
if (opt.verbose)
log_info ("%s: Kyber public key length invalid (%zu)\n",
__func__, kyber_pubkey_len);
err = gpg_error (GPG_ERR_INV_DATA);
goto leave;
}
if (DBG_CRYPTO)
log_printhex (kyber_pubkey, kyber_pubkey_len, "|!trunc|Kyber pubkey:");
err = gcry_kem_encap (kyber_algo,
kyber_pubkey, kyber_pubkey_len,
kyber_ct, kyber_ct_len,
kyber_ss, kyber_ss_len,
NULL, 0);
if (err)
{
if (opt.verbose)
log_info ("%s: gcry_kem_encap for ECC failed\n", __func__);
goto leave;
}
if (DBG_CRYPTO)
{
log_printhex (kyber_ct, kyber_ct_len, "|!trunc|Kyber ephem:");
log_printhex (kyber_ss, kyber_ss_len, "Kyber shared:");
}
fixedinfo[0] = seskey_algo;
v5_fingerprint_from_pk (pk, fixedinfo+1, NULL);
fixedlen = 33;
err = gnupg_kem_combiner (kek, kek_len,
ecc_ss, ecc_ss_len, ecc_ct, ecc_ct_len,
kyber_ss, kyber_ss_len, kyber_ct, kyber_ct_len,
fixedinfo, fixedlen);
if (err)
{
if (opt.verbose)
log_info ("%s: KEM combiner failed\n", __func__);
goto leave;
}
if (DBG_CRYPTO)
log_printhex (kek, kek_len, "KEK:");
err = gcry_cipher_open (&hd, GCRY_CIPHER_AES256,
GCRY_CIPHER_MODE_AESWRAP, 0);
if (!err)
err = gcry_cipher_setkey (hd, kek, kek_len);
if (err)
{
if (opt.verbose)
log_error ("%s: failed to initialize AESWRAP: %s\n", __func__,
gpg_strerror (err));
goto leave;
}
err = gcry_sexp_build (&s_data, NULL, "%m", data);
if (err)
goto leave;
n = gcry_cipher_get_algo_keylen (seskey_algo);
seskey = gcry_mpi_get_opaque (data, &nbits);
seskey_len = (nbits+7)/8;
if (seskey_len != n)
{
if (opt.verbose)
log_info ("%s: session key length %zu"
" does not match the length for algo %d\n",
__func__, seskey_len, seskey_algo);
err = gpg_error (GPG_ERR_INV_DATA);
goto leave;
}
if (DBG_CRYPTO)
log_printhex (seskey, seskey_len, "seskey:");
enc_seskey_len = 1 + seskey_len + 8;
enc_seskey = xtrymalloc (enc_seskey_len);
if (!enc_seskey || enc_seskey_len > 254)
{
err = gpg_error_from_syserror ();
goto leave;
}
enc_seskey[0] = enc_seskey_len - 1;
err = gcry_cipher_encrypt (hd, enc_seskey+1, enc_seskey_len-1,
seskey, seskey_len);
if (err)
{
log_error ("%s: wrapping session key failed\n", __func__);
goto leave;
}
if (DBG_CRYPTO)
log_printhex (enc_seskey, enc_seskey_len, "enc_seskey:");
resarr[0] = gcry_mpi_set_opaque_copy (NULL, ecc_ct, 8 * ecc_ct_len);
if (resarr[0])
resarr[1] = gcry_mpi_set_opaque_copy (NULL, kyber_ct, 8 * kyber_ct_len);
if (resarr[1])
resarr[2] = gcry_mpi_set_opaque_copy (NULL, enc_seskey, 8 * enc_seskey_len);
if (!resarr[0] || !resarr[1] || !resarr[2])
{
err = gpg_error_from_syserror ();
for (i=0; i < 3; i++)
gcry_mpi_release (resarr[i]), resarr[i] = NULL;
}
leave:
wipememory (ecc_ct, sizeof ecc_ct);
wipememory (ecc_ecdh, sizeof ecc_ecdh);
wipememory (ecc_ss, sizeof ecc_ss);
wipememory (kyber_ct, sizeof kyber_ct);
wipememory (kyber_ss, sizeof kyber_ss);
wipememory (kek, kek_len);
xfree (enc_seskey);
gcry_cipher_close (hd);
xfree (ecc_oid);
return err;
}
/* Core of the encryption for the ECDH algorithms. See pk_decrypt for
* a description of the arguments. */
static gpg_error_t
do_encrypt_ecdh (PKT_public_key *pk, gcry_mpi_t data, gcry_mpi_t *resarr)
{
gpg_error_t err;
unsigned int nbits;
gcry_cipher_hd_t hd = NULL;
char *ecc_oid = NULL;
const char *curve;
const struct gnupg_ecc_params *ecc;
const unsigned char *ecc_pubkey;
size_t ecc_pubkey_len;
const unsigned char *seskey;
size_t seskey_len;
unsigned char *enc_seskey = NULL;
size_t enc_seskey_len;
unsigned char ecc_ct[ECC_POINT_LEN_MAX];
unsigned char ecc_ecdh[ECC_POINT_LEN_MAX];
size_t ecc_ct_len, ecc_ecdh_len;
unsigned char *kek = NULL;
size_t kek_len;
const unsigned char *kdf_params_spec;
byte fp[MAX_FINGERPRINT_LEN];
int keywrap_cipher_algo;
int kdf_hash_algo;
unsigned char *kdf_params = NULL;
size_t kdf_params_len = 0;
fingerprint_from_pk (pk, fp, NULL);
ecc_oid = openpgp_oid_to_str (pk->pkey[0]);
if (!ecc_oid)
{
err = gpg_error_from_syserror ();
log_error ("%s: error getting OID for ECC key\n", __func__);
goto leave;
}
curve = openpgp_oid_to_curve (ecc_oid, 1);
if (!curve)
{
err = gpg_error (GPG_ERR_INV_DATA);
log_error ("%s: error getting curve for ECC key\n", __func__);
goto leave;
}
ecc = gnupg_get_ecc_params (curve);
if (!ecc)
{
if (opt.verbose)
log_info ("%s: ECC curve %s not supported\n", __func__, curve);
err = gpg_error (GPG_ERR_INV_DATA);
goto leave;
}
ecc_ct_len = ecc_ecdh_len = ecc->point_len;
ecc_pubkey = gcry_mpi_get_opaque (pk->pkey[1], &nbits);
ecc_pubkey_len = (nbits+7)/8;
if (ecc_pubkey_len != ecc->pubkey_len)
{
if (ecc->kem_algo == GCRY_KEM_RAW_X25519
&& ecc_pubkey_len == ecc->pubkey_len - 1)
/* For Curve25519, we also accept no prefix in the point
* representation. */
;
else
{
if (opt.verbose)
log_info ("%s: ECC public key length invalid (%zu)\n",
__func__, ecc_pubkey_len);
err = gpg_error (GPG_ERR_INV_DATA);
goto leave;
}
}
if (ecc->kem_algo == GCRY_KEM_RAW_X25519)
{
/* Note: Legacy OID is OK here. */
/* Optional prefix handling */
if (ecc_pubkey_len == 33 && *ecc_pubkey == 0x40)
{
ecc_pubkey++; /* Remove the 0x40 prefix. */
ecc_pubkey_len--;
}
}
if (DBG_CRYPTO)
{
log_debug ("ECC curve: %s\n", ecc_oid);
log_printhex (ecc_pubkey, ecc_pubkey_len, "ECC pubkey:");
}
err = gcry_kem_encap (ecc->kem_algo,
ecc_pubkey, ecc_pubkey_len,
ecc_ct, ecc_ct_len,
ecc_ecdh, ecc_ecdh_len,
NULL, 0);
if (err)
{
if (opt.verbose)
log_info ("%s: gcry_kem_encap for ECC (%s) failed\n",
__func__, ecc_oid);
goto leave;
}
if (DBG_CRYPTO)
{
log_printhex (ecc_ct, ecc_ct_len, "ECC ephem:");
log_printhex (ecc_ecdh, ecc_ecdh_len, "ECC ecdh:");
}
err = ecc_build_kdf_params (&kdf_params, &kdf_params_len,
&kdf_params_spec, pk->pkey, fp);
if (err)
return err;
keywrap_cipher_algo = kdf_params_spec[3];
kdf_hash_algo = kdf_params_spec[2];
if (DBG_CRYPTO)
log_debug ("ecdh KDF algorithms %s+%s with aeswrap\n",
openpgp_md_algo_name (kdf_hash_algo),
openpgp_cipher_algo_name (keywrap_cipher_algo));
if (kdf_hash_algo != GCRY_MD_SHA256
&& kdf_hash_algo != GCRY_MD_SHA384
&& kdf_hash_algo != GCRY_MD_SHA512)
{
err = gpg_error (GPG_ERR_BAD_PUBKEY);
goto leave;
}
if (keywrap_cipher_algo != CIPHER_ALGO_AES
&& keywrap_cipher_algo != CIPHER_ALGO_AES192
&& keywrap_cipher_algo != CIPHER_ALGO_AES256)
{
err = gpg_error (GPG_ERR_BAD_PUBKEY);
goto leave;
}
kek_len = gcry_cipher_get_algo_keylen (keywrap_cipher_algo);
if (kek_len > gcry_md_get_algo_dlen (kdf_hash_algo))
{
err = gpg_error (GPG_ERR_BAD_PUBKEY);
goto leave;
}
kek = xtrymalloc (kek_len);
if (!kek)
{
err = gpg_error_from_syserror ();
goto leave;
}
err = gnupg_ecc_kem_kdf (kek, kek_len, kdf_hash_algo,
ecc->is_weierstrauss ?
ecc_ecdh + 1 : ecc_ecdh,
ecc->is_weierstrauss ?
(ecc_ecdh_len - 1) / 2 : ecc_ecdh_len,
NULL, 0, NULL, 0,
kdf_params, kdf_params_len);
xfree (kdf_params);
if (err)
{
if (opt.verbose)
log_info ("%s: kdf for ECC failed\n", __func__);
goto leave;
}
if (DBG_CRYPTO)
log_printhex (kek, kek_len, "KEK:");
err = gcry_cipher_open (&hd, keywrap_cipher_algo,
GCRY_CIPHER_MODE_AESWRAP, 0);
if (!err)
err = gcry_cipher_setkey (hd, kek, kek_len);
if (err)
{
if (opt.verbose)
log_error ("%s: failed to initialize AESWRAP: %s\n", __func__,
gpg_strerror (err));
goto leave;
}
seskey = gcry_mpi_get_opaque (data, &nbits);
seskey_len = (nbits+7)/8;
enc_seskey_len = 1 + seskey_len + 8;
enc_seskey = xtrymalloc (enc_seskey_len);
if (!enc_seskey || enc_seskey_len > 254)
{
err = gpg_error_from_syserror ();
goto leave;
}
enc_seskey[0] = enc_seskey_len - 1;
err = gcry_cipher_encrypt (hd, enc_seskey+1, enc_seskey_len-1,
seskey, seskey_len);
if (err)
{
log_error ("%s: wrapping session key failed\n", __func__);
goto leave;
}
if (DBG_CRYPTO)
log_printhex (enc_seskey, enc_seskey_len, "enc_seskey:");
resarr[0] = gcry_mpi_set_opaque_copy (NULL, ecc_ct, 8 * ecc_ct_len);
if (!resarr[0])
{
err = gpg_error_from_syserror ();
goto leave;
}
resarr[1] = gcry_mpi_set_opaque_copy (NULL, enc_seskey, 8 * enc_seskey_len);
if (!resarr[1])
{
err = gpg_error_from_syserror ();
gcry_mpi_release (resarr[0]);
}
leave:
xfree (enc_seskey);
gcry_cipher_close (hd);
xfree (kek);
wipememory (ecc_ct, sizeof ecc_ct);
wipememory (ecc_ecdh, sizeof ecc_ecdh);
xfree (ecc_oid);
return err;
}
/* Core of the encryption for RSA and Elgamal algorithms. See
* pk_decrypt for a description of the arguments. */
static gpg_error_t
do_encrypt_rsa_elg (PKT_public_key *pk, gcry_mpi_t data, gcry_mpi_t *resarr)
{
pubkey_algo_t algo = pk->pubkey_algo;
gcry_mpi_t *pkey = pk->pkey;
gcry_sexp_t s_ciph = NULL;
gcry_sexp_t s_data = NULL;
gcry_sexp_t s_pkey = NULL;
gpg_error_t err;
if (algo == PUBKEY_ALGO_ELGAMAL || algo == PUBKEY_ALGO_ELGAMAL_E)
err = gcry_sexp_build (&s_pkey, NULL,
"(public-key(elg(p%m)(g%m)(y%m)))",
pkey[0], pkey[1], pkey[2]);
else
err = gcry_sexp_build (&s_pkey, NULL,
"(public-key(rsa(n%m)(e%m)))",
pkey[0], pkey[1]);
if (err)
goto leave;
err = gcry_sexp_build (&s_data, NULL, "%m", data);
if (err)
goto leave;
err = gcry_pk_encrypt (&s_ciph, s_data, s_pkey);
if (err)
goto leave;
gcry_sexp_release (s_data); s_data = NULL;
gcry_sexp_release (s_pkey); s_pkey = NULL;
resarr[0] = get_mpi_from_sexp (s_ciph, "a", GCRYMPI_FMT_USG);
if (!is_RSA (algo))
resarr[1] = get_mpi_from_sexp (s_ciph, "b", GCRYMPI_FMT_USG);
leave:
gcry_sexp_release (s_data);
gcry_sexp_release (s_pkey);
gcry_sexp_release (s_ciph);
return err;
}
/*
* Emulate our old PK interface here - sometime in the future we might
* change the internal design to directly fit to libgcrypt. PK is is
* the OpenPGP public key packet, DATA is an MPI with the to be
* encrypted data, and RESARR receives the encrypted data. RESARRAY
* is expected to be an two/three item array which will be filled with
* newly allocated MPIs. SESKEY_ALGO is required for public key
* algorithms which do not encode it in DATA.
*/
gpg_error_t
pk_encrypt (PKT_public_key *pk, gcry_mpi_t data, int seskey_algo,
gcry_mpi_t *resarr)
{
pubkey_algo_t algo = pk->pubkey_algo;
if (algo == PUBKEY_ALGO_KYBER)
return do_encrypt_kem (pk, data, seskey_algo, resarr);
else if (algo == PUBKEY_ALGO_ECDH)
return do_encrypt_ecdh (pk, data, resarr);
else if (algo == PUBKEY_ALGO_ELGAMAL || algo == PUBKEY_ALGO_ELGAMAL_E)
return do_encrypt_rsa_elg (pk, data, resarr);
else if (algo == PUBKEY_ALGO_RSA || algo == PUBKEY_ALGO_RSA_E)
return do_encrypt_rsa_elg (pk, data, resarr);
else
return gpg_error (GPG_ERR_PUBKEY_ALGO);
}
/* Check whether SKEY is a suitable secret key. */
int
pk_check_secret_key (pubkey_algo_t pkalgo, gcry_mpi_t *skey)
{
gcry_sexp_t s_skey;
int rc;
if (pkalgo == PUBKEY_ALGO_DSA)
{
rc = gcry_sexp_build (&s_skey, NULL,
"(private-key(dsa(p%m)(q%m)(g%m)(y%m)(x%m)))",
skey[0], skey[1], skey[2], skey[3], skey[4]);
}
else if (pkalgo == PUBKEY_ALGO_ELGAMAL || pkalgo == PUBKEY_ALGO_ELGAMAL_E)
{
rc = gcry_sexp_build (&s_skey, NULL,
"(private-key(elg(p%m)(g%m)(y%m)(x%m)))",
skey[0], skey[1], skey[2], skey[3]);
}
else if (is_RSA (pkalgo))
{
rc = gcry_sexp_build (&s_skey, NULL,
"(private-key(rsa(n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))",
skey[0], skey[1], skey[2], skey[3], skey[4],
skey[5]);
}
else if (pkalgo == PUBKEY_ALGO_ECDSA || pkalgo == PUBKEY_ALGO_ECDH)
{
char *curve = openpgp_oid_to_str (skey[0]);
if (!curve)
rc = gpg_error_from_syserror ();
else
{
rc = gcry_sexp_build (&s_skey, NULL,
"(private-key(ecc(curve%s)(q%m)(d%m)))",
curve, skey[1], skey[2]);
xfree (curve);
}
}
else if (pkalgo == PUBKEY_ALGO_EDDSA)
{
char *curve = openpgp_oid_to_str (skey[0]);
if (!curve)
rc = gpg_error_from_syserror ();
else
{
const char *fmt;
if (openpgp_oid_is_ed25519 (skey[0]))
fmt = "(private-key(ecc(curve %s)(flags eddsa)(q%m)(d%m)))";
else
fmt = "(private-key(ecc(curve %s)(q%m)(d%m)))";
rc = gcry_sexp_build (&s_skey, NULL, fmt, curve, skey[1], skey[2]);
xfree (curve);
}
}
else
return GPG_ERR_PUBKEY_ALGO;
if (!rc)
{
rc = gcry_pk_testkey (s_skey);
gcry_sexp_release (s_skey);
}
return rc;
}

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