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975 lines
25 KiB
C
975 lines
25 KiB
C
/* -*- c-basic-offset: 8 -*-
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rdesktop: A Remote Desktop Protocol client.
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Protocol services - RDP encryption and licensing
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Copyright (C) Matthew Chapman 1999-2005
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "rdesktop.h"
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#include <string.h>
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// TODO: remove dependency on OpenSSL
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#include <openssl/rc4.h>
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#include <openssl/md5.h>
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#include <openssl/sha.h>
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#include <openssl/bn.h>
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#include <openssl/x509v3.h>
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/*
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* I believe this is based on SSLv3 with the following differences:
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* MAC algorithm (5.2.3.1) uses only 32-bit length in place of seq_num/type/length fields
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* MAC algorithm uses SHA1 and MD5 for the two hash functions instead of one or other
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* key_block algorithm (6.2.2) uses 'X', 'YY', 'ZZZ' instead of 'A', 'BB', 'CCC'
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* key_block partitioning is different (16 bytes each: MAC secret, decrypt key, encrypt key)
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* encryption/decryption keys updated every 4096 packets
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* See http://wp.netscape.com/eng/ssl3/draft302.txt
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*/
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/*
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* 48-byte transformation used to generate master secret (6.1) and key material (6.2.2).
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* Both SHA1 and MD5 algorithms are used.
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*/
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void
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sec_hash_48(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2, uint8 salt)
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{
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uint8 shasig[20];
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uint8 pad[4];
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SHA_CTX sha;
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MD5_CTX md5;
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int i;
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for (i = 0; i < 3; i++)
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{
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memset(pad, salt + i, i + 1);
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SHA1_Init(&sha);
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SHA1_Update(&sha, pad, i + 1);
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SHA1_Update(&sha, in, 48);
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SHA1_Update(&sha, salt1, 32);
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SHA1_Update(&sha, salt2, 32);
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SHA1_Final(shasig, &sha);
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MD5_Init(&md5);
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MD5_Update(&md5, in, 48);
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MD5_Update(&md5, shasig, 20);
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MD5_Final(&out[i * 16], &md5);
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}
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}
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/*
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* 16-byte transformation used to generate export keys (6.2.2).
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*/
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void
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sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2)
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{
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MD5_CTX md5;
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MD5_Init(&md5);
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MD5_Update(&md5, in, 16);
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MD5_Update(&md5, salt1, 32);
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MD5_Update(&md5, salt2, 32);
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MD5_Final(out, &md5);
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}
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/* Reduce key entropy from 64 to 40 bits */
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static void
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sec_make_40bit(uint8 * key)
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{
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key[0] = 0xd1;
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key[1] = 0x26;
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key[2] = 0x9e;
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}
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/* Generate encryption keys given client and server randoms */
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static void
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sec_generate_keys(RDPCLIENT * This, uint8 * client_random, uint8 * server_random, int rc4_key_size)
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{
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uint8 pre_master_secret[48];
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uint8 master_secret[48];
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uint8 key_block[48];
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/* Construct pre-master secret */
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memcpy(pre_master_secret, client_random, 24);
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memcpy(pre_master_secret + 24, server_random, 24);
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/* Generate master secret and then key material */
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sec_hash_48(master_secret, pre_master_secret, client_random, server_random, 'A');
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sec_hash_48(key_block, master_secret, client_random, server_random, 'X');
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/* First 16 bytes of key material is MAC secret */
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memcpy(This->secure.sign_key, key_block, 16);
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/* Generate export keys from next two blocks of 16 bytes */
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sec_hash_16(This->secure.decrypt_key, &key_block[16], client_random, server_random);
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sec_hash_16(This->secure.encrypt_key, &key_block[32], client_random, server_random);
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if (rc4_key_size == 1)
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{
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DEBUG(("40-bit encryption enabled\n"));
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sec_make_40bit(This->secure.sign_key);
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sec_make_40bit(This->secure.decrypt_key);
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sec_make_40bit(This->secure.encrypt_key);
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This->secure.rc4_key_len = 8;
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}
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else
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{
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DEBUG(("rc_4_key_size == %d, 128-bit encryption enabled\n", rc4_key_size));
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This->secure.rc4_key_len = 16;
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}
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/* Save initial RC4 keys as update keys */
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memcpy(This->secure.decrypt_update_key, This->secure.decrypt_key, 16);
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memcpy(This->secure.encrypt_update_key, This->secure.encrypt_key, 16);
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/* Initialise RC4 state arrays */
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RC4_set_key(&This->secure.rc4_decrypt_key, This->secure.rc4_key_len, This->secure.decrypt_key);
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RC4_set_key(&This->secure.rc4_encrypt_key, This->secure.rc4_key_len, This->secure.encrypt_key);
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}
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static const uint8 pad_54[40] = {
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54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
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54, 54, 54,
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54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
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54, 54, 54
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};
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static const uint8 pad_92[48] = {
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92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
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92, 92, 92, 92, 92, 92, 92,
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92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
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92, 92, 92, 92, 92, 92, 92
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};
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/* Output a uint32 into a buffer (little-endian) */
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void
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buf_out_uint32(uint8 * buffer, uint32 value)
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{
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buffer[0] = (value) & 0xff;
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buffer[1] = (value >> 8) & 0xff;
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buffer[2] = (value >> 16) & 0xff;
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buffer[3] = (value >> 24) & 0xff;
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}
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/* Generate a MAC hash (5.2.3.1), using a combination of SHA1 and MD5 */
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void
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sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen)
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{
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uint8 shasig[20];
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uint8 md5sig[16];
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uint8 lenhdr[4];
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SHA_CTX sha;
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MD5_CTX md5;
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buf_out_uint32(lenhdr, datalen);
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SHA1_Init(&sha);
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SHA1_Update(&sha, session_key, keylen);
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SHA1_Update(&sha, pad_54, 40);
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SHA1_Update(&sha, lenhdr, 4);
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SHA1_Update(&sha, data, datalen);
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SHA1_Final(shasig, &sha);
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MD5_Init(&md5);
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MD5_Update(&md5, session_key, keylen);
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MD5_Update(&md5, pad_92, 48);
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MD5_Update(&md5, shasig, 20);
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MD5_Final(md5sig, &md5);
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memcpy(signature, md5sig, siglen);
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}
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/* Update an encryption key */
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static void
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sec_update(RDPCLIENT * This, uint8 * key, uint8 * update_key)
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{
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uint8 shasig[20];
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SHA_CTX sha;
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MD5_CTX md5;
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RC4_KEY update;
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SHA1_Init(&sha);
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SHA1_Update(&sha, update_key, This->secure.rc4_key_len);
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SHA1_Update(&sha, pad_54, 40);
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SHA1_Update(&sha, key, This->secure.rc4_key_len);
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SHA1_Final(shasig, &sha);
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MD5_Init(&md5);
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MD5_Update(&md5, update_key, This->secure.rc4_key_len);
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MD5_Update(&md5, pad_92, 48);
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MD5_Update(&md5, shasig, 20);
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MD5_Final(key, &md5);
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RC4_set_key(&update, This->secure.rc4_key_len, key);
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RC4(&update, This->secure.rc4_key_len, key, key);
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if (This->secure.rc4_key_len == 8)
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sec_make_40bit(key);
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}
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/* Encrypt data using RC4 */
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static void
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sec_encrypt(RDPCLIENT * This, uint8 * data, int length)
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{
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if (This->secure.encrypt_use_count == 4096)
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{
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sec_update(This, This->secure.encrypt_key, This->secure.encrypt_update_key);
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RC4_set_key(&This->secure.rc4_encrypt_key, This->secure.rc4_key_len, This->secure.encrypt_key);
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This->secure.encrypt_use_count = 0;
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}
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RC4(&This->secure.rc4_encrypt_key, length, data, data);
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This->secure.encrypt_use_count++;
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}
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/* Decrypt data using RC4 */
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void
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sec_decrypt(RDPCLIENT * This, uint8 * data, int length)
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{
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if (This->secure.decrypt_use_count == 4096)
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{
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sec_update(This, This->secure.decrypt_key, This->secure.decrypt_update_key);
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RC4_set_key(&This->secure.rc4_decrypt_key, This->secure.rc4_key_len, This->secure.decrypt_key);
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This->secure.decrypt_use_count = 0;
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}
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RC4(&This->secure.rc4_decrypt_key, length, data, data);
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This->secure.decrypt_use_count++;
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}
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static void
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reverse(uint8 * p, int len)
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{
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int i, j;
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uint8 temp;
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for (i = 0, j = len - 1; i < j; i++, j--)
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{
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temp = p[i];
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p[i] = p[j];
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p[j] = temp;
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}
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}
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/* Perform an RSA public key encryption operation */
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static void
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sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint32 modulus_size, uint8 * modulus,
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uint8 * exponent)
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{
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BN_CTX *ctx;
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BIGNUM mod, exp, x, y;
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uint8 inr[SEC_MAX_MODULUS_SIZE];
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int outlen;
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reverse(modulus, modulus_size);
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reverse(exponent, SEC_EXPONENT_SIZE);
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memcpy(inr, in, len);
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reverse(inr, len);
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ctx = BN_CTX_new();
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BN_init(&mod);
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BN_init(&exp);
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BN_init(&x);
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BN_init(&y);
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BN_bin2bn(modulus, modulus_size, &mod);
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BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp);
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BN_bin2bn(inr, len, &x);
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BN_mod_exp(&y, &x, &exp, &mod, ctx);
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outlen = BN_bn2bin(&y, out);
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reverse(out, outlen);
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if ((uint32)outlen < modulus_size)
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memset(out + outlen, 0, modulus_size - outlen);
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BN_free(&y);
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BN_clear_free(&x);
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BN_free(&exp);
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BN_free(&mod);
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BN_CTX_free(ctx);
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}
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/* Initialise secure transport packet */
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STREAM
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sec_init(RDPCLIENT * This, uint32 flags, int maxlen)
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{
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int hdrlen;
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STREAM s;
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if (!This->licence_issued)
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hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4;
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else
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hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0;
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s = mcs_init(This, maxlen + hdrlen);
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if(s == NULL)
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return s;
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s_push_layer(s, sec_hdr, hdrlen);
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return s;
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}
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/* Transmit secure transport packet over specified channel */
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// !!! we need a lock here !!!
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BOOL
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sec_send_to_channel(RDPCLIENT * This, STREAM s, uint32 flags, uint16 channel)
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{
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int datalen;
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s_pop_layer(s, sec_hdr);
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if (!This->licence_issued || (flags & SEC_ENCRYPT))
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out_uint32_le(s, flags);
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if (flags & SEC_ENCRYPT)
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{
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flags &= ~SEC_ENCRYPT;
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datalen = (int)(s->end - s->p - 8);
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#if WITH_DEBUG
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DEBUG(("Sending encrypted packet:\n"));
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hexdump(s->p + 8, datalen);
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#endif
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sec_sign(s->p, 8, This->secure.sign_key, This->secure.rc4_key_len, s->p + 8, datalen);
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sec_encrypt(This, s->p + 8, datalen);
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}
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return mcs_send_to_channel(This, s, channel);
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}
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/* Transmit secure transport packet */
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BOOL
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sec_send(RDPCLIENT * This, STREAM s, uint32 flags)
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{
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return sec_send_to_channel(This, s, flags, MCS_GLOBAL_CHANNEL);
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}
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/* Transfer the client random to the server */
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static void
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sec_establish_key(RDPCLIENT * This)
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{
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uint32 length = This->secure.server_public_key_len + SEC_PADDING_SIZE;
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uint32 flags = SEC_CLIENT_RANDOM;
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STREAM s;
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s = sec_init(This, flags, length + 4);
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out_uint32_le(s, length);
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out_uint8p(s, This->secure.crypted_random, This->secure.server_public_key_len);
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out_uint8s(s, SEC_PADDING_SIZE);
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s_mark_end(s);
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sec_send(This, s, flags);
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}
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/* Output connect initial data blob */
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static void
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sec_out_mcs_data(RDPCLIENT * This, STREAM s, wchar_t * hostname)
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{
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int hostlen = 2 * (int)wcslen(hostname);
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int length = 158 + 76 + 12 + 4;
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unsigned int i;
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if (This->num_channels > 0)
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length += This->num_channels * 12 + 8;
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if (hostlen > 30)
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hostlen = 30;
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/* Generic Conference Control (T.124) ConferenceCreateRequest */
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out_uint16_be(s, 5);
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out_uint16_be(s, 0x14);
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out_uint8(s, 0x7c);
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out_uint16_be(s, 1);
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out_uint16_be(s, (length | 0x8000)); /* remaining length */
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out_uint16_be(s, 8); /* length? */
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out_uint16_be(s, 16);
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out_uint8(s, 0);
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out_uint16_le(s, 0xc001);
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out_uint8(s, 0);
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out_uint32_le(s, 0x61637544); /* OEM ID: "Duca", as in Ducati. */
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out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */
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/* Client information */
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out_uint16_le(s, SEC_TAG_CLI_INFO);
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out_uint16_le(s, 212); /* length */
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out_uint16_le(s, This->use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */
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out_uint16_le(s, 8);
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out_uint16_le(s, This->width);
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out_uint16_le(s, This->height);
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out_uint16_le(s, 0xca01);
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out_uint16_le(s, 0xaa03);
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out_uint32_le(s, This->keylayout);
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out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */
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/* Unicode name of client, padded to 32 bytes */
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rdp_out_unistr(This, s, hostname, hostlen);
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out_uint8s(s, 30 - hostlen);
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/* See
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http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wceddk40/html/cxtsksupportingremotedesktopprotocol.asp */
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out_uint32_le(s, This->keyboard_type);
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out_uint32_le(s, This->keyboard_subtype);
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out_uint32_le(s, This->keyboard_functionkeys);
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out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */
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out_uint16_le(s, 0xca01); /* colour depth? */
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out_uint16_le(s, 1);
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out_uint32(s, 0);
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out_uint8(s, This->server_depth);
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out_uint16_le(s, 0x0700);
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out_uint8(s, 0);
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out_uint32_le(s, 1);
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out_uint8s(s, 64); /* End of client info */
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out_uint16_le(s, SEC_TAG_CLI_4);
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out_uint16_le(s, 12);
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out_uint32_le(s, This->console_session ? 0xb : 9);
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out_uint32(s, 0);
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/* Client encryption settings */
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out_uint16_le(s, SEC_TAG_CLI_CRYPT);
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out_uint16_le(s, 12); /* length */
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out_uint32_le(s, This->encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */
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out_uint32(s, 0); /* Unknown */
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DEBUG_RDP5(("This->num_channels is %d\n", This->num_channels));
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if (This->num_channels > 0)
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{
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out_uint16_le(s, SEC_TAG_CLI_CHANNELS);
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out_uint16_le(s, This->num_channels * 12 + 8); /* length */
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out_uint32_le(s, This->num_channels); /* number of virtual channels */
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for (i = 0; i < This->num_channels; i++)
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{
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DEBUG_RDP5(("Requesting channel %s\n", This->channels[i].name));
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out_uint8a(s, This->channel_defs[i].name, 8);
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out_uint32_be(s, This->channel_defs[i].options);
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}
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}
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s_mark_end(s);
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}
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/* Parse a public key structure */
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static BOOL
|
|
sec_parse_public_key(RDPCLIENT * This, STREAM s, uint8 ** modulus, uint8 ** exponent)
|
|
{
|
|
uint32 magic, modulus_len;
|
|
|
|
in_uint32_le(s, magic);
|
|
if (magic != SEC_RSA_MAGIC)
|
|
{
|
|
error("RSA magic 0x%x\n", magic);
|
|
return False;
|
|
}
|
|
|
|
in_uint32_le(s, modulus_len);
|
|
modulus_len -= SEC_PADDING_SIZE;
|
|
if ((modulus_len < 64) || (modulus_len > SEC_MAX_MODULUS_SIZE))
|
|
{
|
|
error("Bad server public key size (%u bits)\n", modulus_len * 8);
|
|
return False;
|
|
}
|
|
|
|
in_uint8s(s, 8); /* modulus_bits, unknown */
|
|
in_uint8p(s, *exponent, SEC_EXPONENT_SIZE);
|
|
in_uint8p(s, *modulus, modulus_len);
|
|
in_uint8s(s, SEC_PADDING_SIZE);
|
|
This->secure.server_public_key_len = modulus_len;
|
|
|
|
return s_check(s);
|
|
}
|
|
|
|
static BOOL
|
|
sec_parse_x509_key(RDPCLIENT * This, X509 * cert)
|
|
{
|
|
EVP_PKEY *epk = NULL;
|
|
/* By some reason, Microsoft sets the OID of the Public RSA key to
|
|
the oid for "MD5 with RSA Encryption" instead of "RSA Encryption"
|
|
|
|
Kudos to Richard Levitte for the following (. intiutive .)
|
|
lines of code that resets the OID and let's us extract the key. */
|
|
if (OBJ_obj2nid(cert->cert_info->key->algor->algorithm) == NID_md5WithRSAEncryption)
|
|
{
|
|
DEBUG_RDP5(("Re-setting algorithm type to RSA in server certificate\n"));
|
|
ASN1_OBJECT_free(cert->cert_info->key->algor->algorithm);
|
|
cert->cert_info->key->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption);
|
|
}
|
|
epk = X509_get_pubkey(cert);
|
|
if (NULL == epk)
|
|
{
|
|
error("Failed to extract public key from certificate\n");
|
|
return False;
|
|
}
|
|
|
|
This->secure.server_public_key = RSAPublicKey_dup((RSA *) epk->pkey.ptr);
|
|
EVP_PKEY_free(epk);
|
|
|
|
This->secure.server_public_key_len = RSA_size(This->secure.server_public_key);
|
|
if ((This->secure.server_public_key_len < 64) || (This->secure.server_public_key_len > SEC_MAX_MODULUS_SIZE))
|
|
{
|
|
error("Bad server public key size (%u bits)\n", This->secure.server_public_key_len * 8);
|
|
return False;
|
|
}
|
|
|
|
return True;
|
|
}
|
|
|
|
|
|
/* Parse a crypto information structure */
|
|
static BOOL
|
|
sec_parse_crypt_info(RDPCLIENT * This, STREAM s, uint32 * rc4_key_size,
|
|
uint8 ** server_random, uint8 ** modulus, uint8 ** exponent)
|
|
{
|
|
uint32 crypt_level, random_len, rsa_info_len;
|
|
uint32 cacert_len, cert_len, flags;
|
|
X509 *cacert, *server_cert;
|
|
uint16 tag, length;
|
|
uint8 *next_tag, *end;
|
|
|
|
in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */
|
|
in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */
|
|
if (crypt_level == 0) /* no encryption */
|
|
return False;
|
|
in_uint32_le(s, random_len);
|
|
in_uint32_le(s, rsa_info_len);
|
|
|
|
if (random_len != SEC_RANDOM_SIZE)
|
|
{
|
|
error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE);
|
|
return False;
|
|
}
|
|
|
|
in_uint8p(s, *server_random, random_len);
|
|
|
|
/* RSA info */
|
|
end = s->p + rsa_info_len;
|
|
if (end > s->end)
|
|
return False;
|
|
|
|
in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */
|
|
if (flags & 1)
|
|
{
|
|
DEBUG_RDP5(("We're going for the RDP4-style encryption\n"));
|
|
in_uint8s(s, 8); /* unknown */
|
|
|
|
while (s->p < end)
|
|
{
|
|
in_uint16_le(s, tag);
|
|
in_uint16_le(s, length);
|
|
|
|
next_tag = s->p + length;
|
|
|
|
switch (tag)
|
|
{
|
|
case SEC_TAG_PUBKEY:
|
|
if (!sec_parse_public_key(This, s, modulus, exponent))
|
|
return False;
|
|
DEBUG_RDP5(("Got Public key, RDP4-style\n"));
|
|
|
|
break;
|
|
|
|
case SEC_TAG_KEYSIG:
|
|
/* Is this a Microsoft key that we just got? */
|
|
/* Care factor: zero! */
|
|
/* Actually, it would probably be a good idea to check if the public key is signed with this key, and then store this
|
|
key as a known key of the hostname. This would prevent some MITM-attacks. */
|
|
break;
|
|
|
|
default:
|
|
unimpl("crypt tag 0x%x\n", tag);
|
|
}
|
|
|
|
s->p = next_tag;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
uint32 certcount;
|
|
|
|
DEBUG_RDP5(("We're going for the RDP5-style encryption\n"));
|
|
in_uint32_le(s, certcount); /* Number of certificates */
|
|
|
|
if (certcount < 2)
|
|
{
|
|
error("Server didn't send enough X509 certificates\n");
|
|
This->disconnect_reason = 1798;
|
|
return False;
|
|
}
|
|
|
|
for (; certcount > 2; certcount--)
|
|
{ /* ignore all the certificates between the root and the signing CA */
|
|
uint32 ignorelen;
|
|
X509 *ignorecert;
|
|
|
|
DEBUG_RDP5(("Ignored certs left: %d\n", certcount));
|
|
|
|
in_uint32_le(s, ignorelen);
|
|
DEBUG_RDP5(("Ignored Certificate length is %d\n", ignorelen));
|
|
ignorecert = d2i_X509(NULL, &(s->p), ignorelen);
|
|
|
|
if (ignorecert == NULL)
|
|
{ /* XXX: error out? */
|
|
DEBUG_RDP5(("got a bad cert: this will probably screw up the rest of the communication\n"));
|
|
}
|
|
|
|
#ifdef WITH_DEBUG_RDP5
|
|
DEBUG_RDP5(("cert #%d (ignored):\n", certcount));
|
|
X509_print_fp(stdout, ignorecert);
|
|
#endif
|
|
}
|
|
|
|
/* Do da funky X.509 stuffy
|
|
|
|
"How did I find out about this? I looked up and saw a
|
|
bright light and when I came to I had a scar on my forehead
|
|
and knew about X.500"
|
|
- Peter Gutman in a early version of
|
|
http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt
|
|
*/
|
|
|
|
in_uint32_le(s, cacert_len);
|
|
DEBUG_RDP5(("CA Certificate length is %d\n", cacert_len));
|
|
cacert = d2i_X509(NULL, &(s->p), cacert_len);
|
|
/* Note: We don't need to move s->p here - d2i_X509 is
|
|
"kind" enough to do it for us */
|
|
if (NULL == cacert)
|
|
{
|
|
error("Couldn't load CA Certificate from server\n");
|
|
This->disconnect_reason = 1798;
|
|
return False;
|
|
}
|
|
|
|
/* Currently, we don't use the CA Certificate.
|
|
FIXME:
|
|
*) Verify the server certificate (server_cert) with the
|
|
CA certificate.
|
|
*) Store the CA Certificate with the hostname of the
|
|
server we are connecting to as key, and compare it
|
|
when we connect the next time, in order to prevent
|
|
MITM-attacks.
|
|
*/
|
|
|
|
X509_free(cacert);
|
|
|
|
in_uint32_le(s, cert_len);
|
|
DEBUG_RDP5(("Certificate length is %d\n", cert_len));
|
|
server_cert = d2i_X509(NULL, &(s->p), cert_len);
|
|
if (NULL == server_cert)
|
|
{
|
|
error("Couldn't load Certificate from server\n");
|
|
This->disconnect_reason = 1798;
|
|
return False;
|
|
}
|
|
|
|
in_uint8s(s, 16); /* Padding */
|
|
|
|
/* Note: Verifying the server certificate must be done here,
|
|
before sec_parse_public_key since we'll have to apply
|
|
serious violence to the key after this */
|
|
|
|
if (!sec_parse_x509_key(This, server_cert))
|
|
{
|
|
DEBUG_RDP5(("Didn't parse X509 correctly\n"));
|
|
X509_free(server_cert);
|
|
This->disconnect_reason = 1798;
|
|
return False;
|
|
}
|
|
X509_free(server_cert);
|
|
return True; /* There's some garbage here we don't care about */
|
|
}
|
|
return s_check_end(s);
|
|
}
|
|
|
|
/* Process crypto information blob */
|
|
static void
|
|
sec_process_crypt_info(RDPCLIENT * This, STREAM s)
|
|
{
|
|
uint8 *server_random, *modulus, *exponent;
|
|
uint8 client_random[SEC_RANDOM_SIZE];
|
|
uint32 rc4_key_size;
|
|
|
|
if (!sec_parse_crypt_info(This, s, &rc4_key_size, &server_random, &modulus, &exponent))
|
|
{
|
|
DEBUG(("Failed to parse crypt info\n"));
|
|
return;
|
|
}
|
|
|
|
DEBUG(("Generating client random\n"));
|
|
generate_random(client_random);
|
|
|
|
if (NULL != This->secure.server_public_key)
|
|
{ /* Which means we should use
|
|
RDP5-style encryption */
|
|
uint8 inr[SEC_MAX_MODULUS_SIZE];
|
|
uint32 padding_len = This->secure.server_public_key_len - SEC_RANDOM_SIZE;
|
|
|
|
/* This is what the MS client do: */
|
|
memset(inr, 0, padding_len);
|
|
/* *ARIGL!* Plaintext attack, anyone?
|
|
I tried doing:
|
|
generate_random(inr);
|
|
..but that generates connection errors now and then (yes,
|
|
"now and then". Something like 0 to 3 attempts needed before a
|
|
successful connection. Nice. Not!
|
|
*/
|
|
memcpy(inr + padding_len, client_random, SEC_RANDOM_SIZE);
|
|
reverse(inr + padding_len, SEC_RANDOM_SIZE);
|
|
|
|
RSA_public_encrypt(This->secure.server_public_key_len,
|
|
inr, This->secure.crypted_random, This->secure.server_public_key, RSA_NO_PADDING);
|
|
|
|
reverse(This->secure.crypted_random, This->secure.server_public_key_len);
|
|
|
|
RSA_free(This->secure.server_public_key);
|
|
This->secure.server_public_key = NULL;
|
|
}
|
|
else
|
|
{ /* RDP4-style encryption */
|
|
sec_rsa_encrypt(This->secure.crypted_random,
|
|
client_random, SEC_RANDOM_SIZE, This->secure.server_public_key_len, modulus,
|
|
exponent);
|
|
}
|
|
sec_generate_keys(This, client_random, server_random, rc4_key_size);
|
|
}
|
|
|
|
|
|
/* Process SRV_INFO, find RDP version supported by server */
|
|
static void
|
|
sec_process_srv_info(RDPCLIENT * This, STREAM s)
|
|
{
|
|
in_uint16_le(s, This->server_rdp_version);
|
|
DEBUG_RDP5(("Server RDP version is %d\n", This->server_rdp_version));
|
|
if (1 == This->server_rdp_version)
|
|
{
|
|
This->use_rdp5 = 0;
|
|
This->server_depth = 8;
|
|
}
|
|
}
|
|
|
|
|
|
/* Process connect response data blob */
|
|
void
|
|
sec_process_mcs_data(RDPCLIENT * This, STREAM s)
|
|
{
|
|
uint16 tag, length;
|
|
uint8 *next_tag;
|
|
uint8 len;
|
|
|
|
in_uint8s(s, 21); /* header (T.124 ConferenceCreateResponse) */
|
|
in_uint8(s, len);
|
|
if (len & 0x80)
|
|
in_uint8(s, len);
|
|
|
|
while (s->p < s->end)
|
|
{
|
|
in_uint16_le(s, tag);
|
|
in_uint16_le(s, length);
|
|
|
|
if (length <= 4)
|
|
return;
|
|
|
|
next_tag = s->p + length - 4;
|
|
|
|
switch (tag)
|
|
{
|
|
case SEC_TAG_SRV_INFO:
|
|
sec_process_srv_info(This, s);
|
|
break;
|
|
|
|
case SEC_TAG_SRV_CRYPT:
|
|
sec_process_crypt_info(This, s);
|
|
break;
|
|
|
|
case SEC_TAG_SRV_CHANNELS:
|
|
/* FIXME: We should parse this information and
|
|
use it to map RDP5 channels to MCS
|
|
channels */
|
|
break;
|
|
|
|
default:
|
|
unimpl("response tag 0x%x\n", tag);
|
|
}
|
|
|
|
s->p = next_tag;
|
|
}
|
|
}
|
|
|
|
/* Receive secure transport packet */
|
|
STREAM
|
|
sec_recv(RDPCLIENT * This, uint8 * rdpver)
|
|
{
|
|
uint32 sec_flags;
|
|
uint16 channel;
|
|
STREAM s;
|
|
|
|
while ((s = mcs_recv(This, &channel, rdpver)) != NULL)
|
|
{
|
|
if (rdpver != NULL)
|
|
{
|
|
if (*rdpver != 3)
|
|
{
|
|
if (*rdpver & 0x80)
|
|
{
|
|
in_uint8s(s, 8); /* signature */
|
|
sec_decrypt(This, s->p, (int)(s->end - s->p));
|
|
}
|
|
return s;
|
|
}
|
|
}
|
|
if (This->encryption || !This->licence_issued)
|
|
{
|
|
in_uint32_le(s, sec_flags);
|
|
|
|
if (sec_flags & SEC_ENCRYPT)
|
|
{
|
|
in_uint8s(s, 8); /* signature */
|
|
sec_decrypt(This, s->p, (int)(s->end - s->p));
|
|
}
|
|
|
|
if (sec_flags & SEC_LICENCE_NEG)
|
|
{
|
|
licence_process(This, s);
|
|
continue;
|
|
}
|
|
|
|
if (sec_flags & 0x0400) /* SEC_REDIRECT_ENCRYPT */
|
|
{
|
|
uint8 swapbyte;
|
|
|
|
in_uint8s(s, 8); /* signature */
|
|
sec_decrypt(This, s->p, (int)(s->end - s->p));
|
|
|
|
/* Check for a redirect packet, starts with 00 04 */
|
|
if (s->p[0] == 0 && s->p[1] == 4)
|
|
{
|
|
/* for some reason the PDU and the length seem to be swapped.
|
|
This isn't good, but we're going to do a byte for byte
|
|
swap. So the first foure value appear as: 00 04 XX YY,
|
|
where XX YY is the little endian length. We're going to
|
|
use 04 00 as the PDU type, so after our swap this will look
|
|
like: XX YY 04 00 */
|
|
swapbyte = s->p[0];
|
|
s->p[0] = s->p[2];
|
|
s->p[2] = swapbyte;
|
|
|
|
swapbyte = s->p[1];
|
|
s->p[1] = s->p[3];
|
|
s->p[3] = swapbyte;
|
|
|
|
swapbyte = s->p[2];
|
|
s->p[2] = s->p[3];
|
|
s->p[3] = swapbyte;
|
|
}
|
|
#ifdef WITH_DEBUG
|
|
/* warning! this debug statement will show passwords in the clear! */
|
|
hexdump(s->p, s->end - s->p);
|
|
#endif
|
|
}
|
|
|
|
}
|
|
|
|
if (channel != MCS_GLOBAL_CHANNEL)
|
|
{
|
|
channel_process(This, s, channel);
|
|
*rdpver = 0xff;
|
|
return s;
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/* Establish a secure connection */
|
|
BOOL
|
|
sec_connect(RDPCLIENT * This, char *server, wchar_t *hostname, char *cookie)
|
|
{
|
|
struct stream mcs_data;
|
|
void * p = malloc(512);
|
|
|
|
if(p == NULL)
|
|
{
|
|
This->disconnect_reason = 262;
|
|
return False;
|
|
}
|
|
|
|
/* We exchange some RDP data during the MCS-Connect */
|
|
mcs_data.size = 512;
|
|
mcs_data.p = mcs_data.data = (uint8 *) p;
|
|
sec_out_mcs_data(This, &mcs_data, hostname);
|
|
|
|
if (!mcs_connect(This, server, cookie, &mcs_data))
|
|
return False;
|
|
|
|
/* sec_process_mcs_data(&mcs_data); */
|
|
if (This->encryption)
|
|
sec_establish_key(This);
|
|
free(mcs_data.data);
|
|
return True;
|
|
}
|
|
|
|
/* Establish a secure connection */
|
|
BOOL
|
|
sec_reconnect(RDPCLIENT * This, char *server, wchar_t *hostname, char *cookie)
|
|
{
|
|
struct stream mcs_data;
|
|
void * p = malloc(512);
|
|
|
|
if(p == NULL)
|
|
{
|
|
This->disconnect_reason = 262;
|
|
return False;
|
|
}
|
|
|
|
/* We exchange some RDP data during the MCS-Connect */
|
|
mcs_data.size = 512;
|
|
mcs_data.p = mcs_data.data = (uint8 *) p;
|
|
sec_out_mcs_data(This, &mcs_data, hostname);
|
|
|
|
if (!mcs_reconnect(This, server, cookie, &mcs_data))
|
|
return False;
|
|
|
|
/* sec_process_mcs_data(&mcs_data); */
|
|
if (This->encryption)
|
|
sec_establish_key(This);
|
|
free(mcs_data.data);
|
|
return True;
|
|
}
|
|
|
|
/* Disconnect a connection */
|
|
void
|
|
sec_disconnect(RDPCLIENT * This)
|
|
{
|
|
mcs_disconnect(This);
|
|
}
|
|
|
|
/* reset the state of the sec layer */
|
|
void
|
|
sec_reset_state(RDPCLIENT * This)
|
|
{
|
|
This->server_rdp_version = 0;
|
|
This->secure.encrypt_use_count = 0;
|
|
This->secure.decrypt_use_count = 0;
|
|
mcs_reset_state(This);
|
|
}
|