| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304 | /* *  Diffie-Hellman-Merkle key exchange (client side) * *  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#define mbedtls_time_t     time_t#endif#if defined(MBEDTLS_AES_C) && defined(MBEDTLS_DHM_C) && \    defined(MBEDTLS_ENTROPY_C) && defined(MBEDTLS_NET_C) && \    defined(MBEDTLS_RSA_C) && defined(MBEDTLS_SHA256_C) && \    defined(MBEDTLS_FS_IO) && defined(MBEDTLS_CTR_DRBG_C) && \    defined(MBEDTLS_SHA1_C)#include "mbedtls/net_sockets.h"#include "mbedtls/aes.h"#include "mbedtls/dhm.h"#include "mbedtls/rsa.h"#include "mbedtls/sha1.h"#include "mbedtls/entropy.h"#include "mbedtls/ctr_drbg.h"#include <stdio.h>#include <string.h>#endif#define SERVER_NAME "localhost"#define SERVER_PORT "11999"#if !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_DHM_C) ||     \    !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_NET_C) ||  \    !defined(MBEDTLS_RSA_C) || !defined(MBEDTLS_SHA256_C) ||    \    !defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_CTR_DRBG_C) || \    !defined(MBEDTLS_SHA1_C)int main( void ){    mbedtls_printf("MBEDTLS_AES_C and/or MBEDTLS_DHM_C and/or MBEDTLS_ENTROPY_C "           "and/or MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "           "MBEDTLS_SHA256_C and/or MBEDTLS_FS_IO and/or "           "MBEDTLS_CTR_DRBG_C not defined.\n");    return( 0 );}#elseint main( void ){    FILE *f;    int ret;    size_t n, buflen;    mbedtls_net_context server_fd;    unsigned char *p, *end;    unsigned char buf[2048];    unsigned char hash[32];    const char *pers = "dh_client";    mbedtls_entropy_context entropy;    mbedtls_ctr_drbg_context ctr_drbg;    mbedtls_rsa_context rsa;    mbedtls_dhm_context dhm;    mbedtls_aes_context aes;    mbedtls_net_init( &server_fd );    mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, MBEDTLS_MD_SHA256 );    mbedtls_dhm_init( &dhm );    mbedtls_aes_init( &aes );    mbedtls_ctr_drbg_init( &ctr_drbg );    /*     * 1. Setup the RNG     */    mbedtls_printf( "\n  . 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,                               strlen( pers ) ) ) != 0 )    {        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret );        goto exit;    }    /*     * 2. Read the server's public RSA key     */    mbedtls_printf( "\n  . Reading public key from rsa_pub.txt" );    fflush( stdout );    if( ( f = fopen( "rsa_pub.txt", "rb" ) ) == NULL )    {        ret = 1;        mbedtls_printf( " failed\n  ! Could not open rsa_pub.txt\n" \                "  ! Please run rsa_genkey first\n\n" );        goto exit;    }    mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );    if( ( ret = mbedtls_mpi_read_file( &rsa.N, 16, f ) ) != 0 ||        ( ret = mbedtls_mpi_read_file( &rsa.E, 16, f ) ) != 0 )    {        mbedtls_printf( " failed\n  ! mbedtls_mpi_read_file returned %d\n\n", ret );        fclose( f );        goto exit;    }    rsa.len = ( mbedtls_mpi_bitlen( &rsa.N ) + 7 ) >> 3;    fclose( f );    /*     * 3. Initiate the connection     */    mbedtls_printf( "\n  . Connecting to tcp/%s/%s", SERVER_NAME,                                             SERVER_PORT );    fflush( stdout );    if( ( ret = mbedtls_net_connect( &server_fd, SERVER_NAME,                                         SERVER_PORT, MBEDTLS_NET_PROTO_TCP ) ) != 0 )    {        mbedtls_printf( " failed\n  ! mbedtls_net_connect returned %d\n\n", ret );        goto exit;    }    /*     * 4a. First get the buffer length     */    mbedtls_printf( "\n  . Receiving the server's DH parameters" );    fflush( stdout );    memset( buf, 0, sizeof( buf ) );    if( ( ret = mbedtls_net_recv( &server_fd, buf, 2 ) ) != 2 )    {        mbedtls_printf( " failed\n  ! mbedtls_net_recv returned %d\n\n", ret );        goto exit;    }    n = buflen = ( buf[0] << 8 ) | buf[1];    if( buflen < 1 || buflen > sizeof( buf ) )    {        mbedtls_printf( " failed\n  ! Got an invalid buffer length\n\n" );        goto exit;    }    /*     * 4b. Get the DHM parameters: P, G and Ys = G^Xs mod P     */    memset( buf, 0, sizeof( buf ) );    if( ( ret = mbedtls_net_recv( &server_fd, buf, n ) ) != (int) n )    {        mbedtls_printf( " failed\n  ! mbedtls_net_recv returned %d\n\n", ret );        goto exit;    }    p = buf, end = buf + buflen;    if( ( ret = mbedtls_dhm_read_params( &dhm, &p, end ) ) != 0 )    {        mbedtls_printf( " failed\n  ! mbedtls_dhm_read_params returned %d\n\n", ret );        goto exit;    }    if( dhm.len < 64 || dhm.len > 512 )    {        ret = 1;        mbedtls_printf( " failed\n  ! Invalid DHM modulus size\n\n" );        goto exit;    }    /*     * 5. Check that the server's RSA signature matches     *    the SHA-256 hash of (P,G,Ys)     */    mbedtls_printf( "\n  . Verifying the server's RSA signature" );    fflush( stdout );    p += 2;    if( ( n = (size_t) ( end - p ) ) != rsa.len )    {        ret = 1;        mbedtls_printf( " failed\n  ! Invalid RSA signature size\n\n" );        goto exit;    }    mbedtls_sha1( buf, (int)( p - 2 - buf ), hash );    if( ( ret = mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL, MBEDTLS_RSA_PUBLIC,                                  MBEDTLS_MD_SHA256, 0, hash, p ) ) != 0 )    {        mbedtls_printf( " failed\n  ! mbedtls_rsa_pkcs1_verify returned %d\n\n", ret );        goto exit;    }    /*     * 6. Send our public value: Yc = G ^ Xc mod P     */    mbedtls_printf( "\n  . Sending own public value to server" );    fflush( stdout );    n = dhm.len;    if( ( ret = mbedtls_dhm_make_public( &dhm, (int) dhm.len, buf, n,                                 mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )    {        mbedtls_printf( " failed\n  ! mbedtls_dhm_make_public returned %d\n\n", ret );        goto exit;    }    if( ( ret = mbedtls_net_send( &server_fd, buf, n ) ) != (int) n )    {        mbedtls_printf( " failed\n  ! mbedtls_net_send returned %d\n\n", ret );        goto exit;    }    /*     * 7. Derive the shared secret: K = Ys ^ Xc mod P     */    mbedtls_printf( "\n  . Shared secret: " );    fflush( stdout );    if( ( ret = mbedtls_dhm_calc_secret( &dhm, buf, sizeof( buf ), &n,                                 mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )    {        mbedtls_printf( " failed\n  ! mbedtls_dhm_calc_secret returned %d\n\n", ret );        goto exit;    }    for( n = 0; n < 16; n++ )        mbedtls_printf( "%02x", buf[n] );    /*     * 8. Setup the AES-256 decryption key     *     * This is an overly simplified example; best practice is     * to hash the shared secret with a random value to derive     * the keying material for the encryption/decryption keys,     * IVs and MACs.     */    mbedtls_printf( "...\n  . Receiving and decrypting the ciphertext" );    fflush( stdout );    mbedtls_aes_setkey_dec( &aes, buf, 256 );    memset( buf, 0, sizeof( buf ) );    if( ( ret = mbedtls_net_recv( &server_fd, buf, 16 ) ) != 16 )    {        mbedtls_printf( " failed\n  ! mbedtls_net_recv returned %d\n\n", ret );        goto exit;    }    mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );    buf[16] = '\0';    mbedtls_printf( "\n  . Plaintext is \"%s\"\n\n", (char *) buf );exit:    mbedtls_net_free( &server_fd );    mbedtls_aes_free( &aes );    mbedtls_rsa_free( &rsa );    mbedtls_dhm_free( &dhm );    mbedtls_ctr_drbg_free( &ctr_drbg );    mbedtls_entropy_free( &entropy );#if defined(_WIN32)    mbedtls_printf( "  + Press Enter to exit this program.\n" );    fflush( stdout ); getchar();#endif    return( ret );}#endif /* MBEDTLS_AES_C && MBEDTLS_DHM_C && MBEDTLS_ENTROPY_C &&          MBEDTLS_NET_C && MBEDTLS_RSA_C && MBEDTLS_SHA256_C &&          MBEDTLS_FS_IO && MBEDTLS_CTR_DRBG_C */
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