335 lines
9.9 KiB
C
335 lines
9.9 KiB
C
/*
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* Diffie-Hellman-Merkle key exchange (server side)
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_PLATFORM_C)
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#include "mbedtls/platform.h"
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#else
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#include <stdio.h>
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#include <stdlib.h>
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#define mbedtls_printf printf
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#define mbedtls_time_t time_t
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#define mbedtls_exit exit
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#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
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#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
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#endif /* MBEDTLS_PLATFORM_C */
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#if defined(MBEDTLS_AES_C) && defined(MBEDTLS_DHM_C) && \
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defined(MBEDTLS_ENTROPY_C) && defined(MBEDTLS_NET_C) && \
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defined(MBEDTLS_RSA_C) && defined(MBEDTLS_SHA256_C) && \
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defined(MBEDTLS_FS_IO) && defined(MBEDTLS_CTR_DRBG_C) && \
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defined(MBEDTLS_SHA1_C)
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#include "mbedtls/net_sockets.h"
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#include "mbedtls/aes.h"
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#include "mbedtls/dhm.h"
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#include "mbedtls/rsa.h"
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#include "mbedtls/sha1.h"
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#include "mbedtls/entropy.h"
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#include "mbedtls/ctr_drbg.h"
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#include <stdio.h>
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#include <string.h>
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#endif
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#define SERVER_PORT "11999"
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#define PLAINTEXT "==Hello there!=="
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#if !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_DHM_C) || \
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!defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_NET_C) || \
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!defined(MBEDTLS_RSA_C) || !defined(MBEDTLS_SHA256_C) || \
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!defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_CTR_DRBG_C) || \
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!defined(MBEDTLS_SHA1_C)
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int main( void )
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{
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mbedtls_printf("MBEDTLS_AES_C and/or MBEDTLS_DHM_C and/or MBEDTLS_ENTROPY_C "
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"and/or MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
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"MBEDTLS_SHA256_C and/or MBEDTLS_FS_IO and/or "
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"MBEDTLS_CTR_DRBG_C not defined.\n");
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mbedtls_exit( 0 );
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}
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#else
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int main( void )
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{
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FILE *f;
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int ret = 1;
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int exit_code = MBEDTLS_EXIT_FAILURE;
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size_t n, buflen;
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mbedtls_net_context listen_fd, client_fd;
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unsigned char buf[2048];
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unsigned char hash[32];
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unsigned char buf2[2];
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const char *pers = "dh_server";
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mbedtls_entropy_context entropy;
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mbedtls_ctr_drbg_context ctr_drbg;
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mbedtls_rsa_context rsa;
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mbedtls_dhm_context dhm;
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mbedtls_aes_context aes;
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mbedtls_mpi N, P, Q, D, E;
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mbedtls_net_init( &listen_fd );
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mbedtls_net_init( &client_fd );
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mbedtls_dhm_init( &dhm );
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mbedtls_aes_init( &aes );
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mbedtls_ctr_drbg_init( &ctr_drbg );
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mbedtls_mpi_init( &N ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q );
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mbedtls_mpi_init( &D ); mbedtls_mpi_init( &E );
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/*
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* 1. Setup the RNG
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*/
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mbedtls_printf( "\n . Seeding the random number generator" );
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fflush( stdout );
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mbedtls_entropy_init( &entropy );
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if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
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(const unsigned char *) pers,
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strlen( pers ) ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
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goto exit;
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}
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/*
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* 2a. Read the server's private RSA key
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*/
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mbedtls_printf( "\n . Reading private key from rsa_priv.txt" );
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fflush( stdout );
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if( ( f = fopen( "rsa_priv.txt", "rb" ) ) == NULL )
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{
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mbedtls_printf( " failed\n ! Could not open rsa_priv.txt\n" \
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" ! Please run rsa_genkey first\n\n" );
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goto exit;
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}
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mbedtls_rsa_init( &rsa );
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if( ( ret = mbedtls_mpi_read_file( &N , 16, f ) ) != 0 ||
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( ret = mbedtls_mpi_read_file( &E , 16, f ) ) != 0 ||
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( ret = mbedtls_mpi_read_file( &D , 16, f ) ) != 0 ||
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( ret = mbedtls_mpi_read_file( &P , 16, f ) ) != 0 ||
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( ret = mbedtls_mpi_read_file( &Q , 16, f ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n",
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ret );
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fclose( f );
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goto exit;
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}
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fclose( f );
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if( ( ret = mbedtls_rsa_import( &rsa, &N, &P, &Q, &D, &E ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_rsa_import returned %d\n\n",
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ret );
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goto exit;
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}
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if( ( ret = mbedtls_rsa_complete( &rsa ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_rsa_complete returned %d\n\n",
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ret );
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goto exit;
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}
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/*
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* 2b. Get the DHM modulus and generator
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*/
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mbedtls_printf( "\n . Reading DH parameters from dh_prime.txt" );
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fflush( stdout );
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if( ( f = fopen( "dh_prime.txt", "rb" ) ) == NULL )
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{
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mbedtls_printf( " failed\n ! Could not open dh_prime.txt\n" \
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" ! Please run dh_genprime first\n\n" );
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goto exit;
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}
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if( mbedtls_mpi_read_file( &dhm.MBEDTLS_PRIVATE(P), 16, f ) != 0 ||
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mbedtls_mpi_read_file( &dhm.MBEDTLS_PRIVATE(G), 16, f ) != 0 )
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{
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mbedtls_printf( " failed\n ! Invalid DH parameter file\n\n" );
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fclose( f );
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goto exit;
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}
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fclose( f );
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/*
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* 3. Wait for a client to connect
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*/
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mbedtls_printf( "\n . Waiting for a remote connection" );
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fflush( stdout );
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if( ( ret = mbedtls_net_bind( &listen_fd, NULL, SERVER_PORT, MBEDTLS_NET_PROTO_TCP ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_net_bind returned %d\n\n", ret );
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goto exit;
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}
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if( ( ret = mbedtls_net_accept( &listen_fd, &client_fd,
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NULL, 0, NULL ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_net_accept returned %d\n\n", ret );
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goto exit;
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}
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/*
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* 4. Setup the DH parameters (P,G,Ys)
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*/
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mbedtls_printf( "\n . Sending the server's DH parameters" );
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fflush( stdout );
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memset( buf, 0, sizeof( buf ) );
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if( ( ret = mbedtls_dhm_make_params( &dhm, (int) mbedtls_mpi_size( &dhm.MBEDTLS_PRIVATE(P) ), buf, &n,
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mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_dhm_make_params returned %d\n\n", ret );
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goto exit;
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}
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/*
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* 5. Sign the parameters and send them
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*/
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if( ( ret = mbedtls_sha1( buf, n, hash ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_sha1 returned %d\n\n", ret );
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goto exit;
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}
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buf[n ] = (unsigned char)( rsa.MBEDTLS_PRIVATE(len) >> 8 );
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buf[n + 1] = (unsigned char)( rsa.MBEDTLS_PRIVATE(len) );
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if( ( ret = mbedtls_rsa_pkcs1_sign( &rsa, NULL, NULL, MBEDTLS_MD_SHA256,
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0, hash, buf + n + 2 ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_rsa_pkcs1_sign returned %d\n\n", ret );
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goto exit;
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}
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buflen = n + 2 + rsa.MBEDTLS_PRIVATE(len);
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buf2[0] = (unsigned char)( buflen >> 8 );
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buf2[1] = (unsigned char)( buflen );
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if( ( ret = mbedtls_net_send( &client_fd, buf2, 2 ) ) != 2 ||
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( ret = mbedtls_net_send( &client_fd, buf, buflen ) ) != (int) buflen )
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{
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mbedtls_printf( " failed\n ! mbedtls_net_send returned %d\n\n", ret );
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goto exit;
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}
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/*
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* 6. Get the client's public value: Yc = G ^ Xc mod P
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*/
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mbedtls_printf( "\n . Receiving the client's public value" );
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fflush( stdout );
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memset( buf, 0, sizeof( buf ) );
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n = mbedtls_dhm_get_len( &dhm );
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if( ( ret = mbedtls_net_recv( &client_fd, buf, n ) ) != (int) n )
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{
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mbedtls_printf( " failed\n ! mbedtls_net_recv returned %d\n\n", ret );
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goto exit;
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}
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if( ( ret = mbedtls_dhm_read_public( &dhm, buf, n ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_dhm_read_public returned %d\n\n", ret );
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goto exit;
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}
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/*
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* 7. Derive the shared secret: K = Ys ^ Xc mod P
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*/
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mbedtls_printf( "\n . Shared secret: " );
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fflush( stdout );
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if( ( ret = mbedtls_dhm_calc_secret( &dhm, buf, sizeof( buf ), &n,
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mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
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{
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mbedtls_printf( " failed\n ! mbedtls_dhm_calc_secret returned %d\n\n", ret );
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goto exit;
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}
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for( n = 0; n < 16; n++ )
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mbedtls_printf( "%02x", buf[n] );
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/*
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* 8. Setup the AES-256 encryption key
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*
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* This is an overly simplified example; best practice is
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* to hash the shared secret with a random value to derive
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* the keying material for the encryption/decryption keys
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* and MACs.
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*/
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mbedtls_printf( "...\n . Encrypting and sending the ciphertext" );
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fflush( stdout );
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mbedtls_aes_setkey_enc( &aes, buf, 256 );
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memcpy( buf, PLAINTEXT, 16 );
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mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
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if( ( ret = mbedtls_net_send( &client_fd, buf, 16 ) ) != 16 )
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{
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mbedtls_printf( " failed\n ! mbedtls_net_send returned %d\n\n", ret );
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goto exit;
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}
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mbedtls_printf( "\n\n" );
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exit_code = MBEDTLS_EXIT_SUCCESS;
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exit:
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mbedtls_mpi_free( &N ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q );
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mbedtls_mpi_free( &D ); mbedtls_mpi_free( &E );
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mbedtls_net_free( &client_fd );
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mbedtls_net_free( &listen_fd );
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mbedtls_aes_free( &aes );
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mbedtls_rsa_free( &rsa );
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mbedtls_dhm_free( &dhm );
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mbedtls_ctr_drbg_free( &ctr_drbg );
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mbedtls_entropy_free( &entropy );
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#if defined(_WIN32)
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mbedtls_printf( " + Press Enter to exit this program.\n" );
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fflush( stdout ); getchar();
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#endif
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mbedtls_exit( exit_code );
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}
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#endif /* MBEDTLS_AES_C && MBEDTLS_DHM_C && MBEDTLS_ENTROPY_C &&
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MBEDTLS_NET_C && MBEDTLS_RSA_C && MBEDTLS_SHA256_C &&
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MBEDTLS_FS_IO && MBEDTLS_CTR_DRBG_C */
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