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/*
* Example ECDHE with Curve25519 program
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* 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)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif
#if !defined(MBEDTLS_ECDH_C) || \
!defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED) || \
!defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C)
int main( void )
{
mbedtls_printf( "MBEDTLS_ECDH_C and/or "
"MBEDTLS_ECP_DP_CURVE25519_ENABLED and/or "
"MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C "
"not defined\n" );
return( 0 );
}
#else
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/ecdh.h"
int main( int argc, char *argv[] )
{
int ret;
mbedtls_ecdh_context ctx_cli, ctx_srv;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
unsigned char cli_to_srv[32], srv_to_cli[32];
const char pers[] = "ecdh";
((void) argc);
((void) argv);
mbedtls_ecdh_init( &ctx_cli );
mbedtls_ecdh_init( &ctx_srv );
mbedtls_ctr_drbg_init( &ctr_drbg );
/*
* Initialize random number generation
*/
mbedtls_printf( " . Seeding the random number generator..." );
fflush( stdout );
mbedtls_entropy_init( &entropy );
if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
(const unsigned char *) pers,
sizeof pers ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* Client: inialize context and generate keypair
*/
mbedtls_printf( " . Setting up client context..." );
fflush( stdout );
ret = mbedtls_ecp_group_load( &ctx_cli.grp, MBEDTLS_ECP_DP_CURVE25519 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecp_group_load returned %d\n", ret );
goto exit;
}
ret = mbedtls_ecdh_gen_public( &ctx_cli.grp, &ctx_cli.d, &ctx_cli.Q,
mbedtls_ctr_drbg_random, &ctr_drbg );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdh_gen_public returned %d\n", ret );
goto exit;
}
ret = mbedtls_mpi_write_binary( &ctx_cli.Q.X, cli_to_srv, 32 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_write_binary returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* Server: initialize context and generate keypair
*/
mbedtls_printf( " . Setting up server context..." );
fflush( stdout );
ret = mbedtls_ecp_group_load( &ctx_srv.grp, MBEDTLS_ECP_DP_CURVE25519 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecp_group_load returned %d\n", ret );
goto exit;
}
ret = mbedtls_ecdh_gen_public( &ctx_srv.grp, &ctx_srv.d, &ctx_srv.Q,
mbedtls_ctr_drbg_random, &ctr_drbg );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdh_gen_public returned %d\n", ret );
goto exit;
}
ret = mbedtls_mpi_write_binary( &ctx_srv.Q.X, srv_to_cli, 32 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_write_binary returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* Server: read peer's key and generate shared secret
*/
mbedtls_printf( " . Server reading client key and computing secret..." );
fflush( stdout );
ret = mbedtls_mpi_lset( &ctx_srv.Qp.Z, 1 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_lset returned %d\n", ret );
goto exit;
}
ret = mbedtls_mpi_read_binary( &ctx_srv.Qp.X, cli_to_srv, 32 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_read_binary returned %d\n", ret );
goto exit;
}
ret = mbedtls_ecdh_compute_shared( &ctx_srv.grp, &ctx_srv.z,
&ctx_srv.Qp, &ctx_srv.d,
mbedtls_ctr_drbg_random, &ctr_drbg );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdh_compute_shared returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* Client: read peer's key and generate shared secret
*/
mbedtls_printf( " . Client reading server key and computing secret..." );
fflush( stdout );
ret = mbedtls_mpi_lset( &ctx_cli.Qp.Z, 1 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_lset returned %d\n", ret );
goto exit;
}
ret = mbedtls_mpi_read_binary( &ctx_cli.Qp.X, srv_to_cli, 32 );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_read_binary returned %d\n", ret );
goto exit;
}
ret = mbedtls_ecdh_compute_shared( &ctx_cli.grp, &ctx_cli.z,
&ctx_cli.Qp, &ctx_cli.d,
mbedtls_ctr_drbg_random, &ctr_drbg );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdh_compute_shared returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* Verification: are the computed secret equal?
*/
mbedtls_printf( " . Checking if both computed secrets are equal..." );
fflush( stdout );
ret = mbedtls_mpi_cmp_mpi( &ctx_cli.z, &ctx_srv.z );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ecdh_compute_shared returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
exit:
#if defined(_WIN32)
mbedtls_printf( " + Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
mbedtls_ecdh_free( &ctx_srv );
mbedtls_ecdh_free( &ctx_cli );
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
return( ret != 0 );
}
#endif /* MBEDTLS_ECDH_C && MBEDTLS_ECP_DP_CURVE25519_ENABLED &&
MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C */
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