diff --git a/cipher/ecc-ecdh.c b/cipher/ecc-ecdh.c index 43eb731a..d6b8991a 100644 --- a/cipher/ecc-ecdh.c +++ b/cipher/ecc-ecdh.c @@ -1,126 +1,127 @@ /* ecc-ecdh.c - Elliptic Curve Diffie-Hellman key agreement * Copyright (C) 2019 g10 Code GmbH * * This file is part of Libgcrypt. * * Libgcrypt is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * Libgcrypt 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, see . * SPDX-License-Identifier: LGPL-2.1+ */ #include #include #include #include #include #include "g10lib.h" #include "mpi.h" #include "cipher.h" #include "context.h" #include "ec-context.h" #include "ecc-common.h" #define ECC_CURVE25519_BYTES 32 #define ECC_CURVE448_BYTES 56 static gpg_err_code_t prepare_ec (mpi_ec_t *r_ec, const char *name) { int flags = 0; if (!strcmp (name, "Curve25519")) flags = PUBKEY_FLAG_DJB_TWEAK; return _gcry_mpi_ec_internal_new (r_ec, &flags, "ecc_mul_point", NULL, name); } unsigned int _gcry_ecc_get_algo_keylen (int curveid) { unsigned int len = 0; if (curveid == GCRY_ECC_CURVE25519) len = ECC_CURVE25519_BYTES; else if (curveid == GCRY_ECC_CURVE448) len = ECC_CURVE448_BYTES; return len; } gpg_error_t _gcry_ecc_mul_point (int curveid, unsigned char *result, const unsigned char *scalar, const unsigned char *point) { unsigned int nbits; unsigned int nbytes; const char *curve; gpg_err_code_t err; gcry_mpi_t mpi_k; mpi_ec_t ec; mpi_point_struct Q; gcry_mpi_t x; unsigned int len; unsigned char *buf; if (curveid == GCRY_ECC_CURVE25519) curve = "Curve25519"; else if (curveid == GCRY_ECC_CURVE448) curve = "X448"; else return gpg_error (GPG_ERR_UNKNOWN_CURVE); err = prepare_ec (&ec, curve); if (err) return err; nbits = ec->nbits; nbytes = (nbits + 7)/8; mpi_k = _gcry_mpi_set_opaque_copy (NULL, scalar, nbytes*8); x = mpi_new (nbits); point_init (&Q); if (point) { gcry_mpi_t mpi_u = _gcry_mpi_set_opaque_copy (NULL, point, nbytes*8); mpi_point_struct P; point_init (&P); err = _gcry_ecc_mont_decodepoint (mpi_u, ec, &P); _gcry_mpi_release (mpi_u); if (err) goto leave; _gcry_mpi_ec_mul_point (&Q, mpi_k, &P, ec); point_free (&P); } else _gcry_mpi_ec_mul_point (&Q, mpi_k, ec->G, ec); _gcry_mpi_ec_get_affine (x, NULL, &Q, ec); buf = _gcry_mpi_get_buffer (x, nbytes, &len, NULL); if (!buf) err = gpg_error_from_syserror (); else { memcpy (result, buf, nbytes); xfree (buf); } leave: _gcry_mpi_release (x); point_free (&Q); _gcry_mpi_release (mpi_k); + _gcry_mpi_ec_free (ec); return err; }