programs/pkey/dh_server.c

   1 /*
   2  *  Diffie-Hellman-Merkle key exchange (server side)
   3  *
   4  *  Based on XySSL: Copyright (C) 2006-2008  Christophe Devine
   5  *
   6  *  Copyright (C) 2009  Paul Bakker <polarssl_maintainer at polarssl dot org>
   7  *
   8  *  All rights reserved.
   9  *
  10  *  Redistribution and use in source and binary forms, with or without
  11  *  modification, are permitted provided that the following conditions
  12  *  are met:
  13  *
  14  *    * Redistributions of source code must retain the above copyright
  15  *      notice, this list of conditions and the following disclaimer.
  16  *    * Redistributions in binary form must reproduce the above copyright
  17  *      notice, this list of conditions and the following disclaimer in the
  18  *      documentation and/or other materials provided with the distribution.
  19  *    * Neither the names of PolarSSL or XySSL nor the names of its contributors
  20  *      may be used to endorse or promote products derived from this software
  21  *      without specific prior written permission.
  22  *
  23  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  26  *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  27  *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  28  *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  29  *  TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  30  *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  31  *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  32  *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  33  *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #ifndef _CRT_SECURE_NO_DEPRECATE
  37 #define _CRT_SECURE_NO_DEPRECATE 1
  38 #endif
  39
  40 #include <string.h>
  41 #include <stdio.h>
  42
  43 #include "tropicssl/net.h"
  44 #include "tropicssl/aes.h"
  45 #include "tropicssl/dhm.h"
  46 #include "tropicssl/rsa.h"
  47 #include "tropicssl/sha1.h"
  48 #include "tropicssl/havege.h"
  49
  50 #define SERVER_PORT 11999
  51 #define PLAINTEXT "==Hello there!=="
  52
  53 int main(void)
  54 {
  55         FILE *f;
  56
  57         int ret, n, buflen;
  58         int listen_fd = -1;
  59         int client_fd = -1;
  60
  61         unsigned char buf[1024];
  62         unsigned char hash[20];
  63         unsigned char buf2[2];
  64
  65         havege_state hs;
  66         rsa_context rsa;
  67         dhm_context dhm;
  68         aes_context aes;
  69
  70         memset(&rsa, 0, sizeof(rsa));
  71         memset(&dhm, 0, sizeof(dhm));
  72
  73         /*
  74          * 1. Setup the RNG
  75          */
  76         printf("\n  . Seeding the random number generator");
  77         fflush(stdout);
  78
  79         havege_init(&hs);
  80
  81         /*
  82          * 2a. Read the server's private RSA key
  83          */
  84         printf("\n  . Reading private key from rsa_priv.txt");
  85         fflush(stdout);
  86
  87         if ((f = fopen("rsa_priv.txt", "rb")) == NULL) {
  88                 ret = 1;
  89                 printf(" failed\n  ! Could not open rsa_priv.txt\n"
  90                        "  ! Please run rsa_genkey first\n\n");
  91                 goto exit;
  92         }
  93
  94         rsa_init(&rsa, RSA_PKCS_V15, 0, NULL, NULL);
  95
  96         if ((ret = mpi_read_file(&rsa.N, 16, f)) != 0 ||
  97             (ret = mpi_read_file(&rsa.E, 16, f)) != 0 ||
  98             (ret = mpi_read_file(&rsa.D, 16, f)) != 0 ||
  99             (ret = mpi_read_file(&rsa.P, 16, f)) != 0 ||
 100             (ret = mpi_read_file(&rsa.Q, 16, f)) != 0 ||
 101             (ret = mpi_read_file(&rsa.DP, 16, f)) != 0 ||
 102             (ret = mpi_read_file(&rsa.DQ, 16, f)) != 0 ||
 103             (ret = mpi_read_file(&rsa.QP, 16, f)) != 0) {
 104                 printf(" failed\n  ! mpi_read_file returned %d\n\n", ret);
 105                 goto exit;
 106         }
 107
 108         rsa.len = (mpi_msb(&rsa.N) + 7) >> 3;
 109
 110         fclose(f);
 111
 112         /*
 113          * 2b. Get the DHM modulus and generator
 114          */
 115         printf("\n  . Reading DH parameters from dh_prime.txt");
 116         fflush(stdout);
 117
 118         if ((f = fopen("dh_prime.txt", "rb")) == NULL) {
 119                 ret = 1;
 120                 printf(" failed\n  ! Could not open dh_prime.txt\n"
 121                        "  ! Please run dh_genprime first\n\n");
 122                 goto exit;
 123         }
 124
 125         if (mpi_read_file(&dhm.P, 16, f) != 0 ||
 126             mpi_read_file(&dhm.G, 16, f) != 0) {
 127                 printf(" failed\n  ! Invalid DH parameter file\n\n");
 128                 goto exit;
 129         }
 130
 131         fclose(f);
 132
 133         /*
 134          * 3. Wait for a client to connect
 135          */
 136         printf("\n  . Waiting for a remote connection");
 137         fflush(stdout);
 138
 139         if ((ret = net_bind(&listen_fd, NULL, SERVER_PORT)) != 0) {
 140                 printf(" failed\n  ! net_bind returned %d\n\n", ret);
 141                 goto exit;
 142         }
 143
 144         if ((ret = net_accept(listen_fd, &client_fd, NULL)) != 0) {
 145                 printf(" failed\n  ! net_accept returned %d\n\n", ret);
 146                 goto exit;
 147         }
 148
 149         /*
 150          * 4. Setup the DH parameters (P,G,Ys)
 151          */
 152         printf("\n  . Sending the server's DH parameters");
 153         fflush(stdout);
 154
 155         memset(buf, 0, sizeof(buf));
 156
 157         if ((ret = dhm_make_params(&dhm, 256, buf, &n, havege_rand, &hs)) != 0) {
 158                 printf(" failed\n  ! dhm_make_params returned %d\n\n", ret);
 159                 goto exit;
 160         }
 161
 162         /*
 163          * 5. Sign the parameters and send them
 164          */
 165         sha1(buf, n, hash);
 166
 167         buf[n] = (unsigned char)(rsa.len >> 8);
 168         buf[n + 1] = (unsigned char)(rsa.len);
 169
 170         if ((ret = rsa_pkcs1_sign(&rsa, RSA_PRIVATE, RSA_SHA1,
 171                                   0, hash, buf + n + 2)) != 0) {
 172                 printf(" failed\n  ! rsa_pkcs1_sign returned %d\n\n", ret);
 173                 goto exit;
 174         }
 175
 176         buflen = n + 2 + rsa.len;
 177         buf2[0] = (unsigned char)(buflen >> 8);
 178         buf2[1] = (unsigned char)(buflen);
 179
 180         if ((ret = net_send(&client_fd, buf2, 2)) != 2 ||
 181             (ret = net_send(&client_fd, buf, buflen)) != buflen) {
 182                 printf(" failed\n  ! net_send returned %d\n\n", ret);
 183                 goto exit;
 184         }
 185
 186         /*
 187          * 6. Get the client's public value: Yc = G ^ Xc mod P
 188          */
 189         printf("\n  . Receiving the client's public value");
 190         fflush(stdout);
 191
 192         memset(buf, 0, sizeof(buf));
 193         n = dhm.len;
 194
 195         if ((ret = net_recv(&client_fd, buf, n)) != n) {
 196                 printf(" failed\n  ! net_recv returned %d\n\n", ret);
 197                 goto exit;
 198         }
 199
 200         if ((ret = dhm_read_public(&dhm, buf, dhm.len)) != 0) {
 201                 printf(" failed\n  ! dhm_read_public returned %d\n\n", ret);
 202                 goto exit;
 203         }
 204
 205         /*
 206          * 7. Derive the shared secret: K = Ys ^ Xc mod P
 207          */
 208         printf("\n  . Shared secret: ");
 209         fflush(stdout);
 210
 211         if ((ret = dhm_calc_secret(&dhm, buf, &n)) != 0) {
 212                 printf(" failed\n  ! dhm_calc_secret returned %d\n\n", ret);
 213                 goto exit;
 214         }
 215
 216         for (n = 0; n < 16; n++)
 217                 printf("%02x", buf[n]);
 218
 219         /*
 220          * 8. Setup the AES-256 encryption key
 221          *
 222          * This is an overly simplified example; best practice is
 223          * to hash the shared secret with a random value to derive
 224          * the keying material for the encryption/decryption keys
 225          * and MACs.
 226          */
 227         printf("...\n  . Encrypting and sending the ciphertext");
 228         fflush(stdout);
 229
 230         aes_setkey_enc(&aes, buf, 256);
 231         memcpy(buf, PLAINTEXT, 16);
 232         aes_crypt_ecb(&aes, AES_ENCRYPT, buf, buf);
 233
 234         if ((ret = net_send(&client_fd, buf, 16)) != 16) {
 235                 printf(" failed\n  ! net_send returned %d\n\n", ret);
 236                 goto exit;
 237         }
 238
 239         printf("\n\n");
 240
 241 exit:
 242
 243         net_close(client_fd);
 244         rsa_free(&rsa);
 245         dhm_free(&dhm);
 246
 247 #ifdef WIN32
 248         printf("  + Press Enter to exit this program.\n");
 249         fflush(stdout);
 250         getchar();
 251 #endif
 252
 253         return (ret);
 254 }