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/*
* Copyright (C) 2011-2012 Free Software Foundation, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* The GnuTLS 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.
*
* This library 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 <http://www.gnu.org/licenses/>
*
*/
/* Helper functions for ECC handling
* based on public domain code by Tom St. Dennis.
*/
#include <gnutls_int.h>
#include <gnutls_mpi.h>
#include <gnutls_ecc.h>
#include <algorithms.h>
#include <gnutls_errors.h>
int
_gnutls_ecc_ansi_x963_export(gnutls_ecc_curve_t curve, bigint_t x,
bigint_t y, gnutls_datum_t * out)
{
int numlen = gnutls_ecc_curve_get_size(curve);
int byte_size, ret;
size_t size;
if (numlen == 0)
return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
out->size = 1 + 2 * numlen;
out->data = gnutls_malloc(out->size);
if (out->data == NULL)
return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
memset(out->data, 0, out->size);
/* store byte 0x04 */
out->data[0] = 0x04;
/* pad and store x */
byte_size = (_gnutls_mpi_get_nbits(x) + 7) / 8;
if (numlen < byte_size) {
ret = gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
goto cleanup;
}
size = out->size - (1 + (numlen - byte_size));
ret =
_gnutls_mpi_print(x, &out->data[1 + (numlen - byte_size)],
&size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
byte_size = (_gnutls_mpi_get_nbits(y) + 7) / 8;
if (numlen < byte_size) {
ret = gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
goto cleanup;
}
size = out->size - (1 + (numlen + numlen - byte_size));
ret =
_gnutls_mpi_print(y,
&out->data[1 + numlen + numlen - byte_size],
&size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
/* pad and store y */
return 0;
cleanup:
_gnutls_free_datum(out);
return ret;
}
int
_gnutls_ecc_ansi_x963_import(const uint8_t * in,
unsigned long inlen, bigint_t * x,
bigint_t * y)
{
int ret;
/* must be odd */
if ((inlen & 1) == 0) {
return GNUTLS_E_INVALID_REQUEST;
}
/* check for 4 */
if (in[0] != 4) {
return gnutls_assert_val(GNUTLS_E_PARSING_ERROR);
}
/* read data */
ret = _gnutls_mpi_init_scan(x, in + 1, (inlen - 1) >> 1);
if (ret < 0)
return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
ret =
_gnutls_mpi_init_scan(y, in + 1 + ((inlen - 1) >> 1),
(inlen - 1) >> 1);
if (ret < 0) {
_gnutls_mpi_release(x);
return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
}
return 0;
}
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