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/*
* ECDH with curve-optimized implementation multiplexing
*
* Copyright 2016-2018 INRIA and Microsoft Corporation
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#include "common.h"
#if defined(MBEDTLS_ECDH_C) && defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
#include <mbedtls/ecdh.h>
#if !(defined(__SIZEOF_INT128__) && (__SIZEOF_INT128__ == 16))
#define KRML_VERIFIED_UINT128
#endif
#include <Hacl_Curve25519.h>
#include <mbedtls/platform_util.h>
#include "x25519.h"
#include <string.h>
/*
* Initialize context
*/
void mbedtls_x25519_init( mbedtls_x25519_context *ctx )
{
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x25519_context ) );
}
/*
* Free context
*/
void mbedtls_x25519_free( mbedtls_x25519_context *ctx )
{
if( ctx == NULL )
return;
mbedtls_platform_zeroize( ctx->our_secret, MBEDTLS_X25519_KEY_SIZE_BYTES );
mbedtls_platform_zeroize( ctx->peer_point, MBEDTLS_X25519_KEY_SIZE_BYTES );
}
int mbedtls_x25519_make_params( mbedtls_x25519_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int( *f_rng )(void *, unsigned char *, size_t),
void *p_rng )
{
int ret = 0;
uint8_t base[MBEDTLS_X25519_KEY_SIZE_BYTES] = {0};
if( ( ret = f_rng( p_rng, ctx->our_secret, MBEDTLS_X25519_KEY_SIZE_BYTES ) ) != 0 )
return ret;
*olen = MBEDTLS_X25519_KEY_SIZE_BYTES + 4;
if( blen < *olen )
return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
*buf++ = MBEDTLS_ECP_TLS_NAMED_CURVE;
*buf++ = MBEDTLS_ECP_TLS_CURVE25519 >> 8;
*buf++ = MBEDTLS_ECP_TLS_CURVE25519 & 0xFF;
*buf++ = MBEDTLS_X25519_KEY_SIZE_BYTES;
base[0] = 9;
Hacl_Curve25519_crypto_scalarmult( buf, ctx->our_secret, base );
base[0] = 0;
if( memcmp( buf, base, MBEDTLS_X25519_KEY_SIZE_BYTES) == 0 )
return MBEDTLS_ERR_ECP_RANDOM_FAILED;
return( 0 );
}
int mbedtls_x25519_read_params( mbedtls_x25519_context *ctx,
const unsigned char **buf, const unsigned char *end )
{
if( end - *buf < MBEDTLS_X25519_KEY_SIZE_BYTES + 1 )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
if( ( *(*buf)++ != MBEDTLS_X25519_KEY_SIZE_BYTES ) )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
memcpy( ctx->peer_point, *buf, MBEDTLS_X25519_KEY_SIZE_BYTES );
*buf += MBEDTLS_X25519_KEY_SIZE_BYTES;
return( 0 );
}
int mbedtls_x25519_get_params( mbedtls_x25519_context *ctx, const mbedtls_ecp_keypair *key,
mbedtls_x25519_ecdh_side side )
{
size_t olen = 0;
switch( side ) {
case MBEDTLS_X25519_ECDH_THEIRS:
return mbedtls_ecp_point_write_binary( &key->grp, &key->Q, MBEDTLS_ECP_PF_COMPRESSED, &olen, ctx->peer_point, MBEDTLS_X25519_KEY_SIZE_BYTES );
case MBEDTLS_X25519_ECDH_OURS:
return mbedtls_mpi_write_binary_le( &key->d, ctx->our_secret, MBEDTLS_X25519_KEY_SIZE_BYTES );
default:
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
}
}
int mbedtls_x25519_calc_secret( mbedtls_x25519_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int( *f_rng )(void *, unsigned char *, size_t),
void *p_rng )
{
/* f_rng and p_rng are not used here because this implementation does not
need blinding since it has constant trace. */
(( void )f_rng);
(( void )p_rng);
*olen = MBEDTLS_X25519_KEY_SIZE_BYTES;
if( blen < *olen )
return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
Hacl_Curve25519_crypto_scalarmult( buf, ctx->our_secret, ctx->peer_point);
/* Wipe the DH secret and don't let the peer chose a small subgroup point */
mbedtls_platform_zeroize( ctx->our_secret, MBEDTLS_X25519_KEY_SIZE_BYTES );
if( memcmp( buf, ctx->our_secret, MBEDTLS_X25519_KEY_SIZE_BYTES) == 0 )
return MBEDTLS_ERR_ECP_RANDOM_FAILED;
return( 0 );
}
int mbedtls_x25519_make_public( mbedtls_x25519_context *ctx, size_t *olen,
unsigned char *buf, size_t blen,
int( *f_rng )(void *, unsigned char *, size_t),
void *p_rng )
{
int ret = 0;
unsigned char base[MBEDTLS_X25519_KEY_SIZE_BYTES] = { 0 };
if( ctx == NULL )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
if( ( ret = f_rng( p_rng, ctx->our_secret, MBEDTLS_X25519_KEY_SIZE_BYTES ) ) != 0 )
return ret;
*olen = MBEDTLS_X25519_KEY_SIZE_BYTES + 1;
if( blen < *olen )
return(MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL);
*buf++ = MBEDTLS_X25519_KEY_SIZE_BYTES;
base[0] = 9;
Hacl_Curve25519_crypto_scalarmult( buf, ctx->our_secret, base );
base[0] = 0;
if( memcmp( buf, base, MBEDTLS_X25519_KEY_SIZE_BYTES ) == 0 )
return MBEDTLS_ERR_ECP_RANDOM_FAILED;
return( ret );
}
int mbedtls_x25519_read_public( mbedtls_x25519_context *ctx,
const unsigned char *buf, size_t blen )
{
if( blen < MBEDTLS_X25519_KEY_SIZE_BYTES + 1 )
return(MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL);
if( (*buf++ != MBEDTLS_X25519_KEY_SIZE_BYTES) )
return(MBEDTLS_ERR_ECP_BAD_INPUT_DATA);
memcpy( ctx->peer_point, buf, MBEDTLS_X25519_KEY_SIZE_BYTES );
return( 0 );
}
#endif /* MBEDTLS_ECDH_C && MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED */
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