| /* |
| * Diffie-Hellman-Merkle key exchange (client side) |
| * |
| * Copyright (C) 2006-2010, Brainspark B.V. |
| * |
| * This file is part of PolarSSL (http://www.polarssl.org) |
| * Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org> |
| * |
| * All rights reserved. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| */ |
| |
| #ifndef _CRT_SECURE_NO_DEPRECATE |
| #define _CRT_SECURE_NO_DEPRECATE 1 |
| #endif |
| |
| #include <string.h> |
| #include <stdio.h> |
| |
| #include "polarssl/net.h" |
| #include "polarssl/aes.h" |
| #include "polarssl/dhm.h" |
| #include "polarssl/rsa.h" |
| #include "polarssl/sha1.h" |
| #include "polarssl/havege.h" |
| |
| #define SERVER_NAME "localhost" |
| #define SERVER_PORT 11999 |
| |
| int main( void ) |
| { |
| FILE *f; |
| |
| int ret; |
| size_t n, buflen; |
| int server_fd = -1; |
| |
| unsigned char *p, *end; |
| unsigned char buf[1024]; |
| unsigned char hash[20]; |
| |
| havege_state hs; |
| rsa_context rsa; |
| dhm_context dhm; |
| aes_context aes; |
| |
| memset( &rsa, 0, sizeof( rsa ) ); |
| memset( &dhm, 0, sizeof( dhm ) ); |
| |
| /* |
| * 1. Setup the RNG |
| */ |
| printf( "\n . Seeding the random number generator" ); |
| fflush( stdout ); |
| |
| havege_init( &hs ); |
| |
| /* |
| * 2. Read the server's public RSA key |
| */ |
| printf( "\n . Reading public key from rsa_pub.txt" ); |
| fflush( stdout ); |
| |
| if( ( f = fopen( "rsa_pub.txt", "rb" ) ) == NULL ) |
| { |
| ret = 1; |
| printf( " failed\n ! Could not open rsa_pub.txt\n" \ |
| " ! Please run rsa_genkey first\n\n" ); |
| goto exit; |
| } |
| |
| rsa_init( &rsa, RSA_PKCS_V15, 0 ); |
| |
| if( ( ret = mpi_read_file( &rsa.N, 16, f ) ) != 0 || |
| ( ret = mpi_read_file( &rsa.E, 16, f ) ) != 0 ) |
| { |
| printf( " failed\n ! mpi_read_file returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| rsa.len = ( mpi_msb( &rsa.N ) + 7 ) >> 3; |
| |
| fclose( f ); |
| |
| /* |
| * 3. Initiate the connection |
| */ |
| printf( "\n . Connecting to tcp/%s/%d", SERVER_NAME, |
| SERVER_PORT ); |
| fflush( stdout ); |
| |
| if( ( ret = net_connect( &server_fd, SERVER_NAME, |
| SERVER_PORT ) ) != 0 ) |
| { |
| printf( " failed\n ! net_connect returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| /* |
| * 4a. First get the buffer length |
| */ |
| printf( "\n . Receiving the server's DH parameters" ); |
| fflush( stdout ); |
| |
| memset( buf, 0, sizeof( buf ) ); |
| |
| if( ( ret = net_recv( &server_fd, buf, 2 ) ) != 2 ) |
| { |
| printf( " failed\n ! net_recv returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| n = buflen = ( buf[0] << 8 ) | buf[1]; |
| if( buflen < 1 || buflen > sizeof( buf ) ) |
| { |
| 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 = net_recv( &server_fd, buf, n ) ) != (int) n ) |
| { |
| printf( " failed\n ! net_recv returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| p = buf, end = buf + buflen; |
| |
| if( ( ret = dhm_read_params( &dhm, &p, end ) ) != 0 ) |
| { |
| printf( " failed\n ! dhm_read_params returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| if( dhm.len < 64 || dhm.len > 256 ) |
| { |
| ret = 1; |
| printf( " failed\n ! Invalid DHM modulus size\n\n" ); |
| goto exit; |
| } |
| |
| /* |
| * 5. Check that the server's RSA signature matches |
| * the SHA-1 hash of (P,G,Ys) |
| */ |
| printf( "\n . Verifying the server's RSA signature" ); |
| fflush( stdout ); |
| |
| if( ( n = (size_t) ( end - p ) ) != rsa.len ) |
| { |
| ret = 1; |
| printf( " failed\n ! Invalid RSA signature size\n\n" ); |
| goto exit; |
| } |
| |
| sha1( buf, (int)( p - 2 - buf ), hash ); |
| |
| if( ( ret = rsa_pkcs1_verify( &rsa, RSA_PUBLIC, SIG_RSA_SHA1, |
| 0, hash, p ) ) != 0 ) |
| { |
| printf( " failed\n ! rsa_pkcs1_verify returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| /* |
| * 6. Send our public value: Yc = G ^ Xc mod P |
| */ |
| printf( "\n . Sending own public value to server" ); |
| fflush( stdout ); |
| |
| n = dhm.len; |
| if( ( ret = dhm_make_public( &dhm, 256, buf, n, |
| havege_rand, &hs ) ) != 0 ) |
| { |
| printf( " failed\n ! dhm_make_public returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| if( ( ret = net_send( &server_fd, buf, n ) ) != (int) n ) |
| { |
| printf( " failed\n ! net_send returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| /* |
| * 7. Derive the shared secret: K = Ys ^ Xc mod P |
| */ |
| printf( "\n . Shared secret: " ); |
| fflush( stdout ); |
| |
| n = dhm.len; |
| if( ( ret = dhm_calc_secret( &dhm, buf, &n ) ) != 0 ) |
| { |
| printf( " failed\n ! dhm_calc_secret returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| for( n = 0; n < 16; n++ ) |
| 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. |
| */ |
| printf( "...\n . Receiving and decrypting the ciphertext" ); |
| fflush( stdout ); |
| |
| aes_setkey_dec( &aes, buf, 256 ); |
| |
| memset( buf, 0, sizeof( buf ) ); |
| |
| if( ( ret = net_recv( &server_fd, buf, 16 ) ) != 16 ) |
| { |
| printf( " failed\n ! net_recv returned %d\n\n", ret ); |
| goto exit; |
| } |
| |
| aes_crypt_ecb( &aes, AES_DECRYPT, buf, buf ); |
| buf[16] = '\0'; |
| printf( "\n . Plaintext is \"%s\"\n\n", (char *) buf ); |
| |
| exit: |
| |
| net_close( server_fd ); |
| rsa_free( &rsa ); |
| dhm_free( &dhm ); |
| |
| #ifdef WIN32 |
| printf( " + Press Enter to exit this program.\n" ); |
| fflush( stdout ); getchar(); |
| #endif |
| |
| return( ret ); |
| } |