int main() { /* see http://www.ietf.org/mail-archive/web/tls/current/msg03416.html */ unsigned char key[] = { 0x9b, 0xbe, 0x43, 0x6b, 0xa9, 0x40, 0xf0, 0x17, 0xb1, 0x76, 0x52, 0x84, 0x9a, 0x71, 0xdb, 0x35 }; unsigned char label[] = { 0x74, 0x65, 0x73, 0x74, 0x20, 0x6c, 0x61, 0x62, 0x65, 0x6c}; unsigned char random1[] = { 0xa0, 0xba, 0x9f, 0x93, 0x6c, 0xda, 0x31, 0x18}; unsigned char random2[] = {0x27, 0xa6, 0xf7, 0x96, 0xff, 0xd5, 0x19, 0x8c }; unsigned char buf[200]; size_t result; result = dtls_prf(key, sizeof(key), label, sizeof(label), random1, sizeof(random1), random2, sizeof(random2), buf, 100); printf("PRF yields %zu bytes of random data:\n", result); hexdump(buf, result); printf("\n"); return 0; }
void handle_packet(const u_char *packet, int length) { static int n = 0; static unsigned char initial_hello[] = { 0x16, 0xfe, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; uint8 *data; size_t data_length, rlen; int i, res; #if DTLS_VERSION == 0xfeff #ifndef SHA1_DIGEST_LENGTH #define SHA1_DIGEST_LENGTH 20 #endif uint8 hash_buf[16 + SHA1_DIGEST_LENGTH]; #elif DTLS_VERSION == 0xfefd uint8 hash_buf[DTLS_SHA256_DIGEST_LENGTH]; #endif #define verify_data_length 12 int is_client; n++; SKIP_ETH_HEADER(packet, length); SKIP_IP_HEADER(packet, length); /* determine from port if this is a client */ is_client = dtls_uint16_to_int(packet) != 20220; SKIP_UDP_HEADER(packet, length); while (length) { rlen = dtls_uint16_to_int(packet + 11) + sizeof(dtls_record_header_t); if (!rlen) { fprintf(stderr, "invalid length!\n"); return; } /* skip packet if it is from a different epoch */ if (dtls_uint16_to_int(packet + 3) != epoch[is_client]) goto next; res = decrypt_verify(is_client, packet, rlen, &data, &data_length); if (res <= 0) goto next; printf("packet %d (from %s):\n", n, is_client ? "client" : "server"); hexdump(packet, sizeof(dtls_record_header_t)); printf("\n"); hexdump(data, data_length); printf("\n"); if (packet[0] == 22 && data[0] == 1) { /* ClientHello */ if (memcmp(packet, initial_hello, sizeof(initial_hello)) == 0) goto next; memcpy(dtls_kb_client_iv(OTHER_CONFIG), data + 14, 32); clear_hash(); #if DTLS_VERSION == 0xfeff hs_hash[0] = dtls_new_hash(HASH_MD5); hs_hash[1] = dtls_new_hash(HASH_SHA1); hs_hash[0]->init(hs_hash[0]->data); hs_hash[1]->init(hs_hash[1]->data); #elif DTLS_VERSION == 0xfefd dtls_hash_init(hs_hash[0]); #endif } if (packet[0] == 22 && data[0] == 2) { /* ServerHello */ memcpy(dtls_kb_server_iv(OTHER_CONFIG), data + 14, 32); /* FIXME: search in ciphers */ OTHER_CONFIG->cipher = TLS_PSK_WITH_AES_128_CCM_8; } if (packet[0] == 20 && data[0] == 1) { /* ChangeCipherSpec */ printf("client random: "); dump(dtls_kb_client_iv(OTHER_CONFIG), 32); printf("\nserver random: "); dump(dtls_kb_server_iv(OTHER_CONFIG), 32); printf("\n"); master_secret_len = dtls_prf(pre_master_secret, pre_master_len, (unsigned char *)"master secret", 13, dtls_kb_client_iv(OTHER_CONFIG), 32, dtls_kb_server_iv(OTHER_CONFIG), 32, master_secret, DTLS_MASTER_SECRET_LENGTH); printf("master_secret:\n "); for(i = 0; i < master_secret_len; i++) printf("%02x", master_secret[i]); printf("\n"); /* create key_block from master_secret * key_block = PRF(master_secret, "key expansion" + server_random + client_random) */ dtls_prf(master_secret, master_secret_len, (unsigned char *)"key expansion", 13, dtls_kb_server_iv(OTHER_CONFIG), 32, dtls_kb_client_iv(OTHER_CONFIG), 32, OTHER_CONFIG->key_block, dtls_kb_size(OTHER_CONFIG)); OTHER_CONFIG->read_cipher = dtls_cipher_new(OTHER_CONFIG->cipher, dtls_kb_client_write_key(OTHER_CONFIG), dtls_kb_key_size(OTHER_CONFIG)); if (!OTHER_CONFIG->read_cipher) { warn("cannot create read cipher\n"); } else { dtls_cipher_set_iv(OTHER_CONFIG->read_cipher, dtls_kb_client_iv(OTHER_CONFIG), dtls_kb_iv_size(OTHER_CONFIG)); } OTHER_CONFIG->write_cipher = dtls_cipher_new(OTHER_CONFIG->cipher, dtls_kb_server_write_key(OTHER_CONFIG), dtls_kb_key_size(OTHER_CONFIG)); if (!OTHER_CONFIG->write_cipher) { warn("cannot create write cipher\n"); } else { dtls_cipher_set_iv(OTHER_CONFIG->write_cipher, dtls_kb_server_iv(OTHER_CONFIG), dtls_kb_iv_size(OTHER_CONFIG)); } /* if (is_client) */ SWITCH_CONFIG; epoch[is_client]++; printf("key_block:\n"); printf(" client_MAC_secret:\t"); dump(dtls_kb_client_mac_secret(CURRENT_CONFIG), dtls_kb_mac_secret_size(CURRENT_CONFIG)); printf("\n"); printf(" server_MAC_secret:\t"); dump(dtls_kb_server_mac_secret(CURRENT_CONFIG), dtls_kb_mac_secret_size(CURRENT_CONFIG)); printf("\n"); printf(" client_write_key:\t"); dump(dtls_kb_client_write_key(CURRENT_CONFIG), dtls_kb_key_size(CURRENT_CONFIG)); printf("\n"); printf(" server_write_key:\t"); dump(dtls_kb_server_write_key(CURRENT_CONFIG), dtls_kb_key_size(CURRENT_CONFIG)); printf("\n"); printf(" client_IV:\t\t"); dump(dtls_kb_client_iv(CURRENT_CONFIG), dtls_kb_iv_size(CURRENT_CONFIG)); printf("\n"); printf(" server_IV:\t\t"); dump(dtls_kb_server_iv(CURRENT_CONFIG), dtls_kb_iv_size(CURRENT_CONFIG)); printf("\n"); } if (packet[0] == 22) { if (data[0] == 20) { /* Finished */ finalize_hash(hash_buf); /* clear_hash(); */ update_hash((unsigned char *)packet, sizeof(dtls_record_header_t), data, data_length); dtls_prf(master_secret, master_secret_len, is_client ? (unsigned char *)"client finished" : (unsigned char *)"server finished" , 15, hash_buf, sizeof(hash_buf), NULL, 0, data + sizeof(dtls_handshake_header_t), verify_data_length); printf("verify_data:\n"); dump(data, data_length); printf("\n"); } else { update_hash((unsigned char *)packet, sizeof(dtls_record_header_t), data, data_length); } } if (packet[0] == 23) { /* Application Data */ printf("Application Data:\n"); dump(data, data_length); printf("\n"); } next: length -= rlen; packet += rlen; } }