| /* |
| * Diffie-Hellman-Merkle key exchange (client side) |
| * |
| * Copyright The Mbed TLS Contributors |
| * 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. |
| */ |
| |
| #include "mbedtls/build_info.h" |
| |
| #if defined(MBEDTLS_PLATFORM_C) |
| #include "mbedtls/platform.h" |
| #else |
| #include <stdio.h> |
| #include <stdlib.h> |
| #define mbedtls_printf printf |
| #define mbedtls_time_t time_t |
| #define mbedtls_exit exit |
| #define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS |
| #define MBEDTLS_EXIT_FAILURE EXIT_FAILURE |
| #endif /* MBEDTLS_PLATFORM_C */ |
| |
| #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"); |
| mbedtls_exit( 0 ); |
| } |
| #else |
| |
| |
| int main( void ) |
| { |
| FILE *f; |
| |
| int ret = 1; |
| int exit_code = MBEDTLS_EXIT_FAILURE; |
| 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_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 ) |
| { |
| mbedtls_printf( " failed\n ! Could not open rsa_pub.txt\n" \ |
| " ! Please run rsa_genkey first\n\n" ); |
| goto exit; |
| } |
| |
| mbedtls_rsa_init( &rsa ); |
| |
| if( ( ret = mbedtls_mpi_read_file( &rsa.MBEDTLS_PRIVATE(N), 16, f ) ) != 0 || |
| ( ret = mbedtls_mpi_read_file( &rsa.MBEDTLS_PRIVATE(E), 16, f ) ) != 0 ) |
| { |
| mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n", ret ); |
| fclose( f ); |
| goto exit; |
| } |
| |
| rsa.MBEDTLS_PRIVATE(len) = ( mbedtls_mpi_bitlen( &rsa.MBEDTLS_PRIVATE(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; |
| } |
| |
| n = mbedtls_dhm_get_len( &dhm ); |
| if( n < 64 || n > 512 ) |
| { |
| 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.MBEDTLS_PRIVATE(len) ) |
| { |
| mbedtls_printf( " failed\n ! Invalid RSA signature size\n\n" ); |
| goto exit; |
| } |
| |
| if( ( ret = mbedtls_sha1( buf, (int)( p - 2 - buf ), hash ) ) != 0 ) |
| { |
| mbedtls_printf( " failed\n ! mbedtls_sha1 returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| if( ( ret = mbedtls_rsa_pkcs1_verify( &rsa, MBEDTLS_MD_SHA256, |
| 32, 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 = mbedtls_dhm_get_len( &dhm ); |
| if( ( ret = mbedtls_dhm_make_public( &dhm, (int) n, 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_code = MBEDTLS_EXIT_SUCCESS; |
| |
| 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 |
| |
| mbedtls_exit( exit_code ); |
| } |
| #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 */ |