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/* -*- 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 1999-2002 |
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|
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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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|
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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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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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*/ |
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|
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#include "rdesktop.h" |
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|
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#ifdef WITH_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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#else |
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#include "crypto/rc4.h" |
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#include "crypto/md5.h" |
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#include "crypto/sha.h" |
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#include "crypto/bn.h" |
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#endif |
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|
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extern char hostname[16]; |
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extern int width; |
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extern int height; |
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extern int keylayout; |
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extern BOOL encryption; |
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extern BOOL licence_issued; |
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extern BOOL use_rdp5; |
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extern int server_bpp; |
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|
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static int rc4_key_len; |
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static RC4_KEY rc4_decrypt_key; |
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static RC4_KEY rc4_encrypt_key; |
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static RSA *server_public_key; |
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|
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static uint8 sec_sign_key[16]; |
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static uint8 sec_decrypt_key[16]; |
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static uint8 sec_encrypt_key[16]; |
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static uint8 sec_decrypt_update_key[16]; |
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static uint8 sec_encrypt_update_key[16]; |
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static uint8 sec_crypted_random[SEC_MODULUS_SIZE]; |
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|
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uint16 server_rdp_version = 0; |
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|
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/* |
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* General purpose 48-byte transformation, using two 32-byte salts (generally, |
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* a client and server salt) and a global salt value used for padding. |
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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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|
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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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|
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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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|
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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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/* |
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* Weaker 16-byte transformation, also using two 32-byte salts, but |
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* only using a single round of MD5. |
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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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|
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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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|
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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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|
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/* Generate a session key and RC4 keys, given client and server randoms */ |
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static void |
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sec_generate_keys(uint8 * client_key, uint8 * server_key, int rc4_key_size) |
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{ |
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uint8 session_key[48]; |
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uint8 temp_hash[48]; |
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uint8 input[48]; |
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|
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/* Construct input data to hash */ |
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memcpy(input, client_key, 24); |
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memcpy(input + 24, server_key, 24); |
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|
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/* Generate session key - two rounds of sec_hash_48 */ |
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sec_hash_48(temp_hash, input, client_key, server_key, 65); |
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sec_hash_48(session_key, temp_hash, client_key, server_key, 88); |
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|
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/* Store first 16 bytes of session key, for generating signatures */ |
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memcpy(sec_sign_key, session_key, 16); |
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|
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/* Generate RC4 keys */ |
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sec_hash_16(sec_decrypt_key, &session_key[16], client_key, server_key); |
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sec_hash_16(sec_encrypt_key, &session_key[32], client_key, server_key); |
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|
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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(sec_sign_key); |
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sec_make_40bit(sec_decrypt_key); |
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sec_make_40bit(sec_encrypt_key); |
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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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rc4_key_len = 16; |
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} |
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|
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/* Save initial RC4 keys as update keys */ |
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memcpy(sec_decrypt_update_key, sec_decrypt_key, 16); |
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memcpy(sec_encrypt_update_key, sec_encrypt_key, 16); |
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|
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/* Initialise RC4 state arrays */ |
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RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
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RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
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} |
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|
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static 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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|
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static 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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|
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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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} |
185 |
|
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/* Generate a signature hash, 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) |
189 |
{ |
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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; |
195 |
|
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buf_out_uint32(lenhdr, datalen); |
197 |
|
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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); |
203 |
SHA1_Final(shasig, &sha); |
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|
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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); |
210 |
|
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memcpy(signature, md5sig, siglen); |
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} |
213 |
|
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/* Update an encryption key - similar to the signing process */ |
215 |
static void |
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sec_update(uint8 * key, uint8 * update_key) |
217 |
{ |
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uint8 shasig[20]; |
219 |
SHA_CTX sha; |
220 |
MD5_CTX md5; |
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RC4_KEY update; |
222 |
|
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SHA1_Init(&sha); |
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SHA1_Update(&sha, update_key, rc4_key_len); |
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SHA1_Update(&sha, pad_54, 40); |
226 |
SHA1_Update(&sha, key, rc4_key_len); |
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SHA1_Final(shasig, &sha); |
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|
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MD5_Init(&md5); |
230 |
MD5_Update(&md5, update_key, rc4_key_len); |
231 |
MD5_Update(&md5, pad_92, 48); |
232 |
MD5_Update(&md5, shasig, 20); |
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MD5_Final(key, &md5); |
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|
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RC4_set_key(&update, rc4_key_len, key); |
236 |
RC4(&update, rc4_key_len, key, key); |
237 |
|
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if (rc4_key_len == 8) |
239 |
sec_make_40bit(key); |
240 |
} |
241 |
|
242 |
/* Encrypt data using RC4 */ |
243 |
static void |
244 |
sec_encrypt(uint8 * data, int length) |
245 |
{ |
246 |
static int use_count; |
247 |
|
248 |
if (use_count == 4096) |
249 |
{ |
250 |
sec_update(sec_encrypt_key, sec_encrypt_update_key); |
251 |
RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key); |
252 |
use_count = 0; |
253 |
} |
254 |
|
255 |
RC4(&rc4_encrypt_key, length, data, data); |
256 |
use_count++; |
257 |
} |
258 |
|
259 |
/* Decrypt data using RC4 */ |
260 |
void |
261 |
sec_decrypt(uint8 * data, int length) |
262 |
{ |
263 |
static int use_count; |
264 |
|
265 |
if (use_count == 4096) |
266 |
{ |
267 |
sec_update(sec_decrypt_key, sec_decrypt_update_key); |
268 |
RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key); |
269 |
use_count = 0; |
270 |
} |
271 |
|
272 |
RC4(&rc4_decrypt_key, length, data, data); |
273 |
use_count++; |
274 |
} |
275 |
|
276 |
static void |
277 |
reverse(uint8 * p, int len) |
278 |
{ |
279 |
int i, j; |
280 |
uint8 temp; |
281 |
|
282 |
for (i = 0, j = len - 1; i < j; i++, j--) |
283 |
{ |
284 |
temp = p[i]; |
285 |
p[i] = p[j]; |
286 |
p[j] = temp; |
287 |
} |
288 |
} |
289 |
|
290 |
/* Perform an RSA public key encryption operation */ |
291 |
static void |
292 |
sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint8 * modulus, uint8 * exponent) |
293 |
{ |
294 |
BN_CTX *ctx; |
295 |
BIGNUM mod, exp, x, y; |
296 |
uint8 inr[SEC_MODULUS_SIZE]; |
297 |
int outlen; |
298 |
|
299 |
reverse(modulus, SEC_MODULUS_SIZE); |
300 |
reverse(exponent, SEC_EXPONENT_SIZE); |
301 |
memcpy(inr, in, len); |
302 |
reverse(inr, len); |
303 |
|
304 |
ctx = BN_CTX_new(); |
305 |
BN_init(&mod); |
306 |
BN_init(&exp); |
307 |
BN_init(&x); |
308 |
BN_init(&y); |
309 |
|
310 |
BN_bin2bn(modulus, SEC_MODULUS_SIZE, &mod); |
311 |
BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp); |
312 |
BN_bin2bn(inr, len, &x); |
313 |
BN_mod_exp(&y, &x, &exp, &mod, ctx); |
314 |
outlen = BN_bn2bin(&y, out); |
315 |
reverse(out, outlen); |
316 |
if (outlen < SEC_MODULUS_SIZE) |
317 |
memset(out + outlen, 0, SEC_MODULUS_SIZE - outlen); |
318 |
|
319 |
BN_free(&y); |
320 |
BN_clear_free(&x); |
321 |
BN_free(&exp); |
322 |
BN_free(&mod); |
323 |
BN_CTX_free(ctx); |
324 |
} |
325 |
|
326 |
/* Initialise secure transport packet */ |
327 |
STREAM |
328 |
sec_init(uint32 flags, int maxlen) |
329 |
{ |
330 |
int hdrlen; |
331 |
STREAM s; |
332 |
|
333 |
if (!licence_issued) |
334 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4; |
335 |
else |
336 |
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0; |
337 |
s = mcs_init(maxlen + hdrlen); |
338 |
s_push_layer(s, sec_hdr, hdrlen); |
339 |
|
340 |
return s; |
341 |
} |
342 |
|
343 |
/* Transmit secure transport packet */ |
344 |
void |
345 |
sec_send(STREAM s, uint32 flags) |
346 |
{ |
347 |
int datalen; |
348 |
|
349 |
s_pop_layer(s, sec_hdr); |
350 |
if (!licence_issued || (flags & SEC_ENCRYPT)) |
351 |
out_uint32_le(s, flags); |
352 |
|
353 |
if (flags & SEC_ENCRYPT) |
354 |
{ |
355 |
flags &= ~SEC_ENCRYPT; |
356 |
datalen = s->end - s->p - 8; |
357 |
|
358 |
#if WITH_DEBUG |
359 |
DEBUG(("Sending encrypted packet:\n")); |
360 |
hexdump(s->p + 8, datalen); |
361 |
#endif |
362 |
|
363 |
sec_sign(s->p, 8, sec_sign_key, rc4_key_len, s->p + 8, datalen); |
364 |
sec_encrypt(s->p + 8, datalen); |
365 |
} |
366 |
|
367 |
mcs_send(s); |
368 |
} |
369 |
|
370 |
/* Transfer the client random to the server */ |
371 |
static void |
372 |
sec_establish_key(void) |
373 |
{ |
374 |
uint32 length = SEC_MODULUS_SIZE + SEC_PADDING_SIZE; |
375 |
uint32 flags = SEC_CLIENT_RANDOM; |
376 |
STREAM s; |
377 |
|
378 |
s = sec_init(flags, 76); |
379 |
|
380 |
out_uint32_le(s, length); |
381 |
out_uint8p(s, sec_crypted_random, SEC_MODULUS_SIZE); |
382 |
out_uint8s(s, SEC_PADDING_SIZE); |
383 |
|
384 |
s_mark_end(s); |
385 |
sec_send(s, flags); |
386 |
} |
387 |
|
388 |
/* Output connect initial data blob */ |
389 |
static void |
390 |
sec_out_mcs_data(STREAM s) |
391 |
{ |
392 |
int hostlen = 2 * strlen(hostname); |
393 |
int length = 158 + 76 + 12 + 4 + 20; |
394 |
|
395 |
if (hostlen > 30) |
396 |
hostlen = 30; |
397 |
|
398 |
out_uint16_be(s, 5); /* unknown */ |
399 |
out_uint16_be(s, 0x14); |
400 |
out_uint8(s, 0x7c); |
401 |
out_uint16_be(s, 1); |
402 |
|
403 |
out_uint16_be(s, (length | 0x8000)); /* remaining length */ |
404 |
|
405 |
out_uint16_be(s, 8); /* length? */ |
406 |
out_uint16_be(s, 16); |
407 |
out_uint8(s, 0); |
408 |
out_uint16_le(s, 0xc001); |
409 |
out_uint8(s, 0); |
410 |
|
411 |
out_uint32_le(s, 0x61637544); /* "Duca" ?! */ |
412 |
out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */ |
413 |
|
414 |
/* Client information */ |
415 |
out_uint16_le(s, SEC_TAG_CLI_INFO); |
416 |
out_uint16_le(s, 212); /* length */ |
417 |
out_uint16_le(s, use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */ |
418 |
out_uint16_le(s, 8); |
419 |
out_uint16_le(s, width); |
420 |
out_uint16_le(s, height); |
421 |
out_uint16_le(s, 0xca01); |
422 |
out_uint16_le(s, 0xaa03); |
423 |
out_uint32_le(s, keylayout); |
424 |
out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */ |
425 |
|
426 |
/* Unicode name of client, padded to 32 bytes */ |
427 |
rdp_out_unistr(s, hostname, hostlen); |
428 |
out_uint8s(s, 30 - hostlen); |
429 |
|
430 |
out_uint32_le(s, 4); |
431 |
out_uint32(s, 0); |
432 |
out_uint32_le(s, 12); |
433 |
out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */ |
434 |
|
435 |
switch (server_bpp) |
436 |
{ |
437 |
case 8: |
438 |
out_uint16_le(s, 0xca01); |
439 |
break; |
440 |
case 15: |
441 |
out_uint16_le(s, 0xca02); |
442 |
break; |
443 |
case 16: |
444 |
out_uint16_le(s, 0xca03); |
445 |
break; |
446 |
case 24: |
447 |
out_uint16_le(s, 0xca04); |
448 |
break; |
449 |
} |
450 |
out_uint16_le(s, 1); |
451 |
|
452 |
out_uint32(s, 0); |
453 |
out_uint8(s, server_bpp); |
454 |
out_uint16_le(s, 0x0700); |
455 |
out_uint8(s, 0); |
456 |
out_uint32_le(s, 1); |
457 |
out_uint8s(s, 64); /* End of client info */ |
458 |
|
459 |
out_uint16_le(s, SEC_TAG_CLI_4); |
460 |
out_uint16_le(s, 12); |
461 |
out_uint32_le(s, 9); |
462 |
out_uint32(s, 0); |
463 |
|
464 |
/* Client encryption settings */ |
465 |
out_uint16_le(s, SEC_TAG_CLI_CRYPT); |
466 |
out_uint16_le(s, 12); /* length */ |
467 |
out_uint32_le(s, encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */ |
468 |
out_uint32(s, 0); /* Unknown */ |
469 |
|
470 |
out_uint16_le(s, SEC_TAG_CLI_CHANNELS); |
471 |
out_uint16_le(s, 20); /* length */ |
472 |
out_uint32_le(s, 1); /* number of virtual channels */ |
473 |
out_uint8p(s, "cliprdr", 8); /* name padded to 8(?) */ |
474 |
out_uint16(s, 0); |
475 |
out_uint16_le(s, 0xc0a0); /* Flags. Rumours tell this is documented in MSDN. */ |
476 |
|
477 |
s_mark_end(s); |
478 |
} |
479 |
|
480 |
/* Parse a public key structure */ |
481 |
static BOOL |
482 |
sec_parse_public_key(STREAM s, uint8 ** modulus, uint8 ** exponent) |
483 |
{ |
484 |
uint32 magic, modulus_len; |
485 |
|
486 |
in_uint32_le(s, magic); |
487 |
if (magic != SEC_RSA_MAGIC) |
488 |
{ |
489 |
error("RSA magic 0x%x\n", magic); |
490 |
return False; |
491 |
} |
492 |
|
493 |
in_uint32_le(s, modulus_len); |
494 |
if (modulus_len != SEC_MODULUS_SIZE + SEC_PADDING_SIZE) |
495 |
{ |
496 |
error("modulus len 0x%x\n", modulus_len); |
497 |
return False; |
498 |
} |
499 |
|
500 |
in_uint8s(s, 8); /* modulus_bits, unknown */ |
501 |
in_uint8p(s, *exponent, SEC_EXPONENT_SIZE); |
502 |
in_uint8p(s, *modulus, SEC_MODULUS_SIZE); |
503 |
in_uint8s(s, SEC_PADDING_SIZE); |
504 |
|
505 |
return s_check(s); |
506 |
} |
507 |
|
508 |
static BOOL |
509 |
sec_parse_x509_key(X509 * cert) |
510 |
{ |
511 |
EVP_PKEY *epk = NULL; |
512 |
/* By some reason, Microsoft sets the OID of the Public RSA key to |
513 |
the oid for "MD5 with RSA Encryption" instead of "RSA Encryption" |
514 |
|
515 |
Kudos to Richard Levitte for the following (. intiutive .) |
516 |
lines of code that resets the OID and let's us extract the key. */ |
517 |
if (OBJ_obj2nid(cert->cert_info->key->algor->algorithm) == NID_md5WithRSAEncryption) |
518 |
{ |
519 |
DEBUG_RDP5(("Re-setting algorithm type to RSA in server certificate\n")); |
520 |
cert->cert_info->key->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption); |
521 |
} |
522 |
epk = X509_get_pubkey(cert); |
523 |
if (NULL == epk) |
524 |
{ |
525 |
error("Failed to extract public key from certificate\n"); |
526 |
return False; |
527 |
} |
528 |
|
529 |
server_public_key = (RSA *) epk->pkey.ptr; |
530 |
|
531 |
return True; |
532 |
} |
533 |
|
534 |
|
535 |
/* Parse a crypto information structure */ |
536 |
static BOOL |
537 |
sec_parse_crypt_info(STREAM s, uint32 * rc4_key_size, |
538 |
uint8 ** server_random, uint8 ** modulus, uint8 ** exponent) |
539 |
{ |
540 |
uint32 crypt_level, random_len, rsa_info_len; |
541 |
uint32 cacert_len, cert_len, flags; |
542 |
X509 *cacert, *server_cert; |
543 |
uint16 tag, length; |
544 |
uint8 *next_tag, *end; |
545 |
|
546 |
in_uint32_le(s, *rc4_key_size); /* 1 = 40-bit, 2 = 128-bit */ |
547 |
in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */ |
548 |
if (crypt_level == 0) /* no encryption */ |
549 |
return False; |
550 |
in_uint32_le(s, random_len); |
551 |
in_uint32_le(s, rsa_info_len); |
552 |
|
553 |
if (random_len != SEC_RANDOM_SIZE) |
554 |
{ |
555 |
error("random len %d, expected %d\n", random_len, SEC_RANDOM_SIZE); |
556 |
return False; |
557 |
} |
558 |
|
559 |
in_uint8p(s, *server_random, random_len); |
560 |
|
561 |
/* RSA info */ |
562 |
end = s->p + rsa_info_len; |
563 |
if (end > s->end) |
564 |
return False; |
565 |
|
566 |
in_uint32_le(s, flags); /* 1 = RDP4-style, 0x80000002 = X.509 */ |
567 |
if (flags & 1) |
568 |
{ |
569 |
DEBUG_RDP5(("We're going for the RDP4-style encryption\n")); |
570 |
in_uint8s(s, 8); /* unknown */ |
571 |
|
572 |
while (s->p < end) |
573 |
{ |
574 |
in_uint16_le(s, tag); |
575 |
in_uint16_le(s, length); |
576 |
|
577 |
next_tag = s->p + length; |
578 |
|
579 |
switch (tag) |
580 |
{ |
581 |
case SEC_TAG_PUBKEY: |
582 |
if (!sec_parse_public_key(s, modulus, exponent)) |
583 |
return False; |
584 |
DEBUG_RDP5(("Got Public key, RDP4-style\n")); |
585 |
|
586 |
break; |
587 |
|
588 |
case SEC_TAG_KEYSIG: |
589 |
/* Is this a Microsoft key that we just got? */ |
590 |
/* Care factor: zero! */ |
591 |
/* Actually, it would probably be a good idea to check if the public key is signed with this key, and then store this |
592 |
key as a known key of the hostname. This would prevent some MITM-attacks. */ |
593 |
break; |
594 |
|
595 |
default: |
596 |
unimpl("crypt tag 0x%x\n", tag); |
597 |
} |
598 |
|
599 |
s->p = next_tag; |
600 |
} |
601 |
} |
602 |
else |
603 |
{ |
604 |
DEBUG_RDP5(("We're going for the RDP5-style encryption\n")); |
605 |
in_uint8s(s, 4); /* Number of certificates */ |
606 |
|
607 |
/* Do da funky X.509 stuffy |
608 |
|
609 |
"How did I find out about this? I looked up and saw a |
610 |
bright light and when I came to I had a scar on my forehead |
611 |
and knew about X.500" |
612 |
- Peter Gutman in a early version of |
613 |
http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt |
614 |
*/ |
615 |
|
616 |
in_uint32_le(s, cacert_len); |
617 |
cacert = d2i_X509(NULL, &(s->p), cacert_len); |
618 |
/* Note: We don't need to move s->p here - d2i_X509 is |
619 |
"kind" enough to do it for us */ |
620 |
if (NULL == cacert) |
621 |
{ |
622 |
error("Couldn't load CA Certificate from server\n"); |
623 |
return False; |
624 |
} |
625 |
|
626 |
/* Currently, we don't use the CA Certificate. |
627 |
FIXME: |
628 |
*) Verify the server certificate (server_cert) with the |
629 |
CA certificate. |
630 |
*) Store the CA Certificate with the hostname of the |
631 |
server we are connecting to as key, and compare it |
632 |
when we connect the next time, in order to prevent |
633 |
MITM-attacks. |
634 |
*/ |
635 |
|
636 |
in_uint32_le(s, cert_len); |
637 |
server_cert = d2i_X509(NULL, &(s->p), cert_len); |
638 |
if (NULL == server_cert) |
639 |
{ |
640 |
error("Couldn't load Certificate from server\n"); |
641 |
return False; |
642 |
} |
643 |
|
644 |
in_uint8s(s, 16); /* Padding */ |
645 |
|
646 |
/* Note: Verifying the server certificate must be done here, |
647 |
before sec_parse_public_key since we'll have to apply |
648 |
serious violence to the key after this */ |
649 |
|
650 |
if (!sec_parse_x509_key(server_cert)) |
651 |
{ |
652 |
DEBUG_RDP5(("Didn't parse X509 correctly\n")); |
653 |
return False; |
654 |
} |
655 |
return True; /* There's some garbage here we don't care about */ |
656 |
} |
657 |
return s_check_end(s); |
658 |
} |
659 |
|
660 |
/* Process crypto information blob */ |
661 |
static void |
662 |
sec_process_crypt_info(STREAM s) |
663 |
{ |
664 |
uint8 *server_random, *modulus, *exponent; |
665 |
uint8 client_random[SEC_RANDOM_SIZE]; |
666 |
uint32 rc4_key_size; |
667 |
uint8 inr[SEC_MODULUS_SIZE]; |
668 |
|
669 |
if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent)) |
670 |
{ |
671 |
DEBUG(("Failed to parse crypt info\n")); |
672 |
return; |
673 |
} |
674 |
|
675 |
DEBUG(("Generating client random\n")); |
676 |
/* Generate a client random, and hence determine encryption keys */ |
677 |
generate_random(inr); |
678 |
// This is what the MS client do: |
679 |
// memset(inr, 0, SEC_RANDOM_SIZE); |
680 |
// *ARIGL!* |
681 |
generate_random(client_random); |
682 |
if (NULL != server_public_key) |
683 |
{ /* Which means we should use |
684 |
RDP5-style encryption */ |
685 |
|
686 |
memcpy(inr + SEC_RANDOM_SIZE, client_random, SEC_RANDOM_SIZE); |
687 |
reverse(inr + SEC_RANDOM_SIZE, SEC_RANDOM_SIZE); |
688 |
|
689 |
RSA_public_encrypt(SEC_MODULUS_SIZE, |
690 |
inr, sec_crypted_random, server_public_key, RSA_NO_PADDING); |
691 |
|
692 |
reverse(sec_crypted_random, SEC_MODULUS_SIZE); |
693 |
|
694 |
} |
695 |
else |
696 |
{ /* RDP4-style encryption */ |
697 |
sec_rsa_encrypt(sec_crypted_random, |
698 |
client_random, SEC_RANDOM_SIZE, modulus, exponent); |
699 |
} |
700 |
sec_generate_keys(client_random, server_random, rc4_key_size); |
701 |
} |
702 |
|
703 |
|
704 |
/* Process SRV_INFO, find RDP version supported by server */ |
705 |
static void |
706 |
sec_process_srv_info(STREAM s) |
707 |
{ |
708 |
in_uint16_le(s, server_rdp_version); |
709 |
DEBUG_RDP5(("Server RDP version is %d\n", server_rdp_version)); |
710 |
} |
711 |
|
712 |
|
713 |
/* Process connect response data blob */ |
714 |
void |
715 |
sec_process_mcs_data(STREAM s) |
716 |
{ |
717 |
uint16 tag, length; |
718 |
uint8 *next_tag; |
719 |
uint8 len; |
720 |
|
721 |
in_uint8s(s, 21); /* header (T.124 stuff, probably) */ |
722 |
in_uint8(s, len); |
723 |
if (len & 0x80) |
724 |
in_uint8(s, len); |
725 |
|
726 |
while (s->p < s->end) |
727 |
{ |
728 |
in_uint16_le(s, tag); |
729 |
in_uint16_le(s, length); |
730 |
|
731 |
if (length <= 4) |
732 |
return; |
733 |
|
734 |
next_tag = s->p + length - 4; |
735 |
|
736 |
switch (tag) |
737 |
{ |
738 |
case SEC_TAG_SRV_INFO: |
739 |
sec_process_srv_info(s); |
740 |
break; |
741 |
|
742 |
case SEC_TAG_SRV_3: |
743 |
break; |
744 |
|
745 |
case SEC_TAG_SRV_CRYPT: |
746 |
sec_process_crypt_info(s); |
747 |
break; |
748 |
|
749 |
default: |
750 |
unimpl("response tag 0x%x\n", tag); |
751 |
} |
752 |
|
753 |
s->p = next_tag; |
754 |
} |
755 |
} |
756 |
|
757 |
/* Receive secure transport packet */ |
758 |
STREAM |
759 |
sec_recv(void) |
760 |
{ |
761 |
uint32 sec_flags; |
762 |
uint16 channel; |
763 |
STREAM s; |
764 |
|
765 |
while ((s = mcs_recv(&channel)) != NULL) |
766 |
{ |
767 |
if (encryption || !licence_issued) |
768 |
{ |
769 |
in_uint32_le(s, sec_flags); |
770 |
|
771 |
if (sec_flags & SEC_LICENCE_NEG) |
772 |
{ |
773 |
if (sec_flags & SEC_ENCRYPT) { |
774 |
DEBUG_RDP5(("Encrypted license detected\n")); |
775 |
} |
776 |
licence_process(s); |
777 |
continue; |
778 |
} |
779 |
|
780 |
if (sec_flags & SEC_ENCRYPT) |
781 |
{ |
782 |
in_uint8s(s, 8); /* signature */ |
783 |
sec_decrypt(s->p, s->end - s->p); |
784 |
} |
785 |
} |
786 |
|
787 |
if (MCS_GLOBAL_CHANNEL == channel) |
788 |
{ |
789 |
return s; |
790 |
} |
791 |
else |
792 |
rdp5_process_channel(s, channel); |
793 |
|
794 |
} |
795 |
|
796 |
return NULL; |
797 |
} |
798 |
|
799 |
/* Establish a secure connection */ |
800 |
BOOL |
801 |
sec_connect(char *server, char *username) |
802 |
{ |
803 |
struct stream mcs_data; |
804 |
|
805 |
/* We exchange some RDP data during the MCS-Connect */ |
806 |
mcs_data.size = 512; |
807 |
mcs_data.p = mcs_data.data = (uint8*)xmalloc(mcs_data.size); |
808 |
sec_out_mcs_data(&mcs_data); |
809 |
|
810 |
if (!mcs_connect(server, &mcs_data, username)) |
811 |
return False; |
812 |
|
813 |
// sec_process_mcs_data(&mcs_data); |
814 |
if (encryption) |
815 |
sec_establish_key(); |
816 |
xfree(mcs_data.data); |
817 |
return True; |
818 |
} |
819 |
|
820 |
/* Disconnect a connection */ |
821 |
void |
822 |
sec_disconnect(void) |
823 |
{ |
824 |
mcs_disconnect(); |
825 |
} |