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xrdp-proprietary/uirdesktop/secure.c

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/* -*- c-basic-offset: 8 -*-
rdesktop: A Remote Desktop Protocol client.
Protocol services - RDP encryption and licensing
Copyright (C) Matthew Chapman 1999-2005
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "rdesktop.h"
//#include <openssl/rc4.h>
//#include <openssl/md5.h>
//#include <openssl/sha.h>
//#include <openssl/bn.h>
//#include <openssl/x509v3.h>
void *
ssl_sha1_info_create(void);
void
ssl_sha1_info_delete(void * sha1_info);
void
ssl_sha1_clear(void * sha1_info);
void
ssl_sha1_transform(void * sha1_info, char * data, int len);
void
ssl_sha1_complete(void * sha1_info, char * data);
void *
ssl_md5_info_create(void);
void
ssl_md5_info_delete(void * md5_info);
void *
ssl_md5_info_create(void);
void
ssl_md5_info_delete(void * md5_info);
void
ssl_md5_clear(void * md5_info);
void
ssl_md5_transform(void * md5_info, char * data, int len);
void
ssl_md5_complete(void * md5_info, char * data);
void *
ssl_rc4_info_create(void);
void
ssl_rc4_info_delete(void * rc4_info);
void
ssl_rc4_set_key(void * rc4_info, char * key, int len);
void
ssl_rc4_crypt(void * rc4_info, char * in_data, char * out_data, int len);
int
ssl_mod_exp(char* out, int out_len, char* in, int in_len,
char* mod, int mod_len, char* exp, int exp_len);
extern char g_hostname[16];
extern int g_width;
extern int g_height;
extern unsigned int g_keylayout;
extern int g_keyboard_type;
extern int g_keyboard_subtype;
extern int g_keyboard_functionkeys;
extern BOOL g_encryption;
extern BOOL g_licence_issued;
extern BOOL g_use_rdp5;
extern BOOL g_console_session;
extern int g_server_depth;
extern uint16 mcs_userid;
extern VCHANNEL g_channels[];
extern unsigned int g_num_channels;
static int rc4_key_len;
static void * rc4_decrypt_key = 0;
static void * rc4_encrypt_key = 0;
//static RSA *server_public_key;
static void * server_public_key;
static uint32 server_public_key_len;
static uint8 sec_sign_key[16];
static uint8 sec_decrypt_key[16];
static uint8 sec_encrypt_key[16];
static uint8 sec_decrypt_update_key[16];
static uint8 sec_encrypt_update_key[16];
static uint8 sec_crypted_random[SEC_MAX_MODULUS_SIZE];
uint16 g_server_rdp_version = 0;
/* These values must be available to reset state - Session Directory */
static int sec_encrypt_use_count = 0;
static int sec_decrypt_use_count = 0;
/*
* I believe this is based on SSLv3 with the following differences:
* MAC algorithm (5.2.3.1) uses only 32-bit length in place of seq_num/type/length fields
* MAC algorithm uses SHA1 and MD5 for the two hash functions instead of one or other
* key_block algorithm (6.2.2) uses 'X', 'YY', 'ZZZ' instead of 'A', 'BB', 'CCC'
* key_block partitioning is different (16 bytes each: MAC secret, decrypt key, encrypt key)
* encryption/decryption keys updated every 4096 packets
* See http://wp.netscape.com/eng/ssl3/draft302.txt
*/
/*
* 48-byte transformation used to generate master secret (6.1) and key material (6.2.2).
* Both SHA1 and MD5 algorithms are used.
*/
void
sec_hash_48(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2, uint8 salt)
{
uint8 shasig[20];
uint8 pad[4];
void * sha;
void * md5;
int i;
for (i = 0; i < 3; i++)
{
memset(pad, salt + i, i + 1);
sha = ssl_sha1_info_create();
ssl_sha1_clear(sha);
ssl_sha1_transform(sha, pad, i + 1);
ssl_sha1_transform(sha, in, 48);
ssl_sha1_transform(sha, salt1, 32);
ssl_sha1_transform(sha, salt2, 32);
ssl_sha1_complete(sha, shasig);
ssl_sha1_info_delete(sha);
md5 = ssl_md5_info_create();
ssl_md5_clear(md5);
ssl_md5_transform(md5, in, 48);
ssl_md5_transform(md5, shasig, 20);
ssl_md5_complete(md5, out + i * 16);
ssl_md5_info_delete(md5);
}
}
/*
* 16-byte transformation used to generate export keys (6.2.2).
*/
void
sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2)
{
void * md5;
md5 = ssl_md5_info_create();
ssl_md5_clear(md5);
ssl_md5_transform(md5, in, 16);
ssl_md5_transform(md5, salt1, 32);
ssl_md5_transform(md5, salt2, 32);
ssl_md5_complete(md5, out);
ssl_md5_info_delete(md5);
}
/* Reduce key entropy from 64 to 40 bits */
static void
sec_make_40bit(uint8 * key)
{
key[0] = 0xd1;
key[1] = 0x26;
key[2] = 0x9e;
}
/* Generate encryption keys given client and server randoms */
static void
sec_generate_keys(uint8 * client_random, uint8 * server_random, int rc4_key_size)
{
uint8 pre_master_secret[48];
uint8 master_secret[48];
uint8 key_block[48];
/* Construct pre-master secret */
memcpy(pre_master_secret, client_random, 24);
memcpy(pre_master_secret + 24, server_random, 24);
/* Generate master secret and then key material */
sec_hash_48(master_secret, pre_master_secret, client_random, server_random, 'A');
sec_hash_48(key_block, master_secret, client_random, server_random, 'X');
/* First 16 bytes of key material is MAC secret */
memcpy(sec_sign_key, key_block, 16);
/* Generate export keys from next two blocks of 16 bytes */
sec_hash_16(sec_decrypt_key, &key_block[16], client_random, server_random);
sec_hash_16(sec_encrypt_key, &key_block[32], client_random, server_random);
if (rc4_key_size == 1)
{
DEBUG(("40-bit encryption enabled\n"));
sec_make_40bit(sec_sign_key);
sec_make_40bit(sec_decrypt_key);
sec_make_40bit(sec_encrypt_key);
rc4_key_len = 8;
}
else
{
DEBUG(("rc_4_key_size == %d, 128-bit encryption enabled\n", rc4_key_size));
rc4_key_len = 16;
}
/* Save initial RC4 keys as update keys */
memcpy(sec_decrypt_update_key, sec_decrypt_key, 16);
memcpy(sec_encrypt_update_key, sec_encrypt_key, 16);
/* Initialise RC4 state arrays */
ssl_rc4_info_delete(rc4_decrypt_key);
rc4_decrypt_key = ssl_rc4_info_create();
ssl_rc4_set_key(rc4_decrypt_key, sec_decrypt_key, rc4_key_len);
ssl_rc4_info_delete(rc4_encrypt_key);
rc4_encrypt_key = ssl_rc4_info_create();
ssl_rc4_set_key(rc4_encrypt_key, sec_encrypt_key, rc4_key_len);
}
static uint8 pad_54[40] = {
54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
54, 54, 54,
54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
54, 54, 54
};
static uint8 pad_92[48] = {
92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
92, 92, 92, 92, 92, 92, 92,
92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
92, 92, 92, 92, 92, 92, 92
};
/* Output a uint32 into a buffer (little-endian) */
void
buf_out_uint32(uint8 * buffer, uint32 value)
{
buffer[0] = (value) & 0xff;
buffer[1] = (value >> 8) & 0xff;
buffer[2] = (value >> 16) & 0xff;
buffer[3] = (value >> 24) & 0xff;
}
/* Generate a MAC hash (5.2.3.1), using a combination of SHA1 and MD5 */
void
sec_sign(uint8 * signature, int siglen, uint8 * session_key, int keylen, uint8 * data, int datalen)
{
uint8 shasig[20];
uint8 md5sig[16];
uint8 lenhdr[4];
void * sha;
void * md5;
buf_out_uint32(lenhdr, datalen);
sha = ssl_sha1_info_create();
ssl_sha1_clear(sha);
ssl_sha1_transform(sha, session_key, keylen);
ssl_sha1_transform(sha, pad_54, 40);
ssl_sha1_transform(sha, lenhdr, 4);
ssl_sha1_transform(sha, data, datalen);
ssl_sha1_complete(sha, shasig);
ssl_sha1_info_delete(sha);
md5 = ssl_md5_info_create();
ssl_md5_clear(md5);
ssl_md5_transform(md5, session_key, keylen);
ssl_md5_transform(md5, pad_92, 48);
ssl_md5_transform(md5, shasig, 20);
ssl_md5_complete(md5, md5sig);
ssl_md5_info_delete(md5);
memcpy(signature, md5sig, siglen);
}
/* Update an encryption key */
static void
sec_update(uint8 * key, uint8 * update_key)
{
uint8 shasig[20];
void * sha;
void * md5;
void * update;
sha = ssl_sha1_info_create();
ssl_sha1_clear(sha);
ssl_sha1_transform(sha, update_key, rc4_key_len);
ssl_sha1_transform(sha, pad_54, 40);
ssl_sha1_transform(sha, key, rc4_key_len);
ssl_sha1_complete(sha, shasig);
ssl_sha1_info_delete(sha);
md5 = ssl_md5_info_create();
ssl_md5_clear(md5);
ssl_md5_transform(md5, update_key, rc4_key_len);
ssl_md5_transform(md5, pad_92, 48);
ssl_md5_transform(md5, shasig, 20);
ssl_md5_complete(md5, key);
ssl_md5_info_delete(md5);
update = ssl_rc4_info_create();
ssl_rc4_set_key(update, key, rc4_key_len);
ssl_rc4_crypt(update, key, key, rc4_key_len);
ssl_rc4_info_delete(update);
if (rc4_key_len == 8)
sec_make_40bit(key);
}
/* Encrypt data using RC4 */
static void
sec_encrypt(uint8 * data, int length)
{
if (sec_encrypt_use_count == 4096)
{
sec_update(sec_encrypt_key, sec_encrypt_update_key);
ssl_rc4_set_key(rc4_encrypt_key, sec_encrypt_key, rc4_key_len);
sec_encrypt_use_count = 0;
}
ssl_rc4_crypt(rc4_encrypt_key, data, data, length);
sec_encrypt_use_count++;
}
/* Decrypt data using RC4 */
void
sec_decrypt(uint8 * data, int length)
{
if (sec_decrypt_use_count == 4096)
{
sec_update(sec_decrypt_key, sec_decrypt_update_key);
ssl_rc4_set_key(rc4_decrypt_key, sec_decrypt_key, rc4_key_len);
sec_decrypt_use_count = 0;
}
ssl_rc4_crypt(rc4_decrypt_key, data, data, length);
sec_decrypt_use_count++;
}
/*static void
reverse(uint8 * p, int len)
{
int i, j;
uint8 temp;
for (i = 0, j = len - 1; i < j; i++, j--)
{
temp = p[i];
p[i] = p[j];
p[j] = temp;
}
}*/
/* Perform an RSA public key encryption operation */
static void
sec_rsa_encrypt(uint8 * out, uint8 * in, int len, uint32 modulus_size, uint8 * modulus,
uint8 * exponent)
{
ssl_mod_exp(out, 64, in, 32, modulus, modulus_size, exponent, 4);
/*
BN_CTX *ctx;
BIGNUM mod, exp, x, y;
uint8 inr[SEC_MODULUS_SIZE];
int outlen;
reverse(modulus, SEC_MODULUS_SIZE);
reverse(exponent, SEC_EXPONENT_SIZE);
memcpy(inr, in, len);
reverse(inr, len);
ctx = BN_CTX_new();
BN_init(&mod);
BN_init(&exp);
BN_init(&x);
BN_init(&y);
BN_bin2bn(modulus, SEC_MODULUS_SIZE, &mod);
BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp);
BN_bin2bn(inr, len, &x);
BN_mod_exp(&y, &x, &exp, &mod, ctx);
outlen = BN_bn2bin(&y, out);
reverse(out, outlen);
if (outlen < SEC_MODULUS_SIZE)
memset(out + outlen, 0, SEC_MODULUS_SIZE - outlen);
BN_free(&y);
BN_clear_free(&x);
BN_free(&exp);
BN_free(&mod);
BN_CTX_free(ctx);*/
}
/* Initialise secure transport packet */
STREAM
sec_init(uint32 flags, int maxlen)
{
int hdrlen;
STREAM s;
if (!g_licence_issued)
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4;
else
hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0;
s = mcs_init(maxlen + hdrlen);
s_push_layer(s, sec_hdr, hdrlen);
return s;
}
/* Transmit secure transport packet over specified channel */
void
sec_send_to_channel(STREAM s, uint32 flags, uint16 channel)
{
int datalen;
s_pop_layer(s, sec_hdr);
if (!g_licence_issued || (flags & SEC_ENCRYPT))
out_uint32_le(s, flags);
if (flags & SEC_ENCRYPT)
{
flags &= ~SEC_ENCRYPT;
datalen = s->end - s->p - 8;
#ifdef WITH_DEBUG
DEBUG(("Sending encrypted packet:\n"));
hexdump(s->p + 8, datalen);
#endif
sec_sign(s->p, 8, sec_sign_key, rc4_key_len, s->p + 8, datalen);
sec_encrypt(s->p + 8, datalen);
}
mcs_send_to_channel(s, channel);
}
/* Transmit secure transport packet */
void
sec_send(STREAM s, uint32 flags)
{
sec_send_to_channel(s, flags, MCS_GLOBAL_CHANNEL);
}
/* Transfer the client random to the server */
static void
sec_establish_key(void)
{
uint32 length = server_public_key_len + SEC_PADDING_SIZE;
uint32 flags = SEC_CLIENT_RANDOM;
STREAM s;
s = sec_init(flags, length+4);
out_uint32_le(s, length);
out_uint8p(s, sec_crypted_random, server_public_key_len);
out_uint8s(s, SEC_PADDING_SIZE);
s_mark_end(s);
sec_send(s, flags);
}
/* Output connect initial data blob */
static void
sec_out_mcs_data(STREAM s)
{
int hostlen = 2 * strlen(g_hostname);
int length = 158 + 76 + 12 + 4;
unsigned int i;
if (g_num_channels > 0)
length += g_num_channels * 12 + 8;
if (hostlen > 30)
hostlen = 30;
/* Generic Conference Control (T.124) ConferenceCreateRequest */
out_uint16_be(s, 5);
out_uint16_be(s, 0x14);
out_uint8(s, 0x7c);
out_uint16_be(s, 1);
out_uint16_be(s, (length | 0x8000)); /* remaining length */
out_uint16_be(s, 8); /* length? */
out_uint16_be(s, 16);
out_uint8(s, 0);
out_uint16_le(s, 0xc001);
out_uint8(s, 0);
out_uint32_le(s, 0x61637544); /* OEM ID: "Duca", as in Ducati. */
out_uint16_be(s, ((length - 14) | 0x8000)); /* remaining length */
/* Client information */
out_uint16_le(s, SEC_TAG_CLI_INFO);
out_uint16_le(s, 212); /* length */
out_uint16_le(s, g_use_rdp5 ? 4 : 1); /* RDP version. 1 == RDP4, 4 == RDP5. */
out_uint16_le(s, 8);
out_uint16_le(s, g_width);
out_uint16_le(s, g_height);
out_uint16_le(s, 0xca01);
out_uint16_le(s, 0xaa03);
out_uint32_le(s, g_keylayout);
out_uint32_le(s, 2600); /* Client build. We are now 2600 compatible :-) */
/* Unicode name of client, padded to 32 bytes */
rdp_out_unistr(s, g_hostname, hostlen);
out_uint8s(s, 30 - hostlen);
/* See
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wceddk40/html/cxtsksupportingremotedesktopprotocol.asp */
out_uint32_le(s, g_keyboard_type);
out_uint32_le(s, g_keyboard_subtype);
out_uint32_le(s, g_keyboard_functionkeys);
out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */
out_uint16_le(s, 0xca01); /* colour depth? */
out_uint16_le(s, 1);
out_uint32(s, 0);
out_uint8(s, g_server_depth);
out_uint16_le(s, 0x0700);
out_uint8(s, 0);
out_uint32_le(s, 1);
out_uint8s(s, 64); /* End of client info */
out_uint16_le(s, SEC_TAG_CLI_4);
out_uint16_le(s, 12);
out_uint32_le(s, g_console_session ? 0xb : 9);
out_uint32(s, 0);
/* Client encryption settings */
out_uint16_le(s, SEC_TAG_CLI_CRYPT);
out_uint16_le(s, 12); /* length */
out_uint32_le(s, g_encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */
out_uint32(s, 0); /* Unknown */
DEBUG_RDP5(("g_num_channels is %d\n", g_num_channels));
if (g_num_channels > 0)
{
out_uint16_le(s, SEC_TAG_CLI_CHANNELS);
out_uint16_le(s, g_num_channels * 12 + 8); /* length */
out_uint32_le(s, g_num_channels); /* number of virtual channels */
for (i = 0; i < g_num_channels; i++)
{
DEBUG_RDP5(("Requesting channel %s\n", g_channels[i].name));
out_uint8a(s, g_channels[i].name, 8);
out_uint32_be(s, g_channels[i].flags);
}
}
s_mark_end(s);
}
/* Parse a public key structure */
static BOOL
sec_parse_public_key(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);
server_public_key_len = modulus_len;
return s_check(s);
}
/* Parse a crypto information structure */
static BOOL
sec_parse_crypt_info(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(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
{
#if 0
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");
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");
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");
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(server_cert))
{
DEBUG_RDP5(("Didn't parse X509 correctly\n"));
X509_free(server_cert);
return False;
}
X509_free(server_cert);
return True; /* There's some garbage here we don't care about */
#endif
}
return s_check_end(s);
}
/* Process crypto information blob */
static void
sec_process_crypt_info(STREAM s)
{
uint8 *server_random, *modulus, *exponent;
uint8 client_random[SEC_RANDOM_SIZE];
uint32 rc4_key_size;
uint8 inr[SEC_MODULUS_SIZE];
if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random, &modulus, &exponent))
{
DEBUG(("Failed to parse crypt info\n"));
return;
}
DEBUG(("Generating client random\n"));
/* Generate a client random, and hence determine encryption keys */
/* This is what the MS client do: */
memset(inr, 0, SEC_RANDOM_SIZE);
/* *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!
*/
generate_random(client_random);
if (NULL != server_public_key)
{ /* Which means we should use
RDP5-style encryption */
#if 0
memcpy(inr + SEC_RANDOM_SIZE, client_random, SEC_RANDOM_SIZE);
reverse(inr + SEC_RANDOM_SIZE, SEC_RANDOM_SIZE);
RSA_public_encrypt(SEC_MODULUS_SIZE,
inr, sec_crypted_random, server_public_key, RSA_NO_PADDING);
reverse(sec_crypted_random, SEC_MODULUS_SIZE);
RSA_free(server_public_key);
server_public_key = NULL;
#endif
}
else
{ /* RDP4-style encryption */
sec_rsa_encrypt(sec_crypted_random,
client_random, SEC_RANDOM_SIZE, server_public_key_len, modulus, exponent);
}
sec_generate_keys(client_random, server_random, rc4_key_size);
}
/* Process SRV_INFO, find RDP version supported by server */
static void
sec_process_srv_info(STREAM s)
{
in_uint16_le(s, g_server_rdp_version);
DEBUG_RDP5(("Server RDP version is %d\n", g_server_rdp_version));
if (1 == g_server_rdp_version)
{
g_use_rdp5 = 0;
g_server_depth = 8;
}
}
/* Process connect response data blob */
void
sec_process_mcs_data(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(s);
break;
case SEC_TAG_SRV_CRYPT:
sec_process_crypt_info(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(uint8 * rdpver)
{
uint32 sec_flags;
uint16 channel;
STREAM s;
while ((s = mcs_recv(&channel, rdpver)) != NULL)
{
if (rdpver != NULL)
{
if (*rdpver != 3)
{
if (*rdpver & 0x80)
{
in_uint8s(s, 8); /* signature */
sec_decrypt(s->p, s->end - s->p);
}
return s;
}
}
if (g_encryption || !g_licence_issued)
{
in_uint32_le(s, sec_flags);
if (sec_flags & SEC_ENCRYPT)
{
in_uint8s(s, 8); /* signature */
sec_decrypt(s->p, s->end - s->p);
}
if (sec_flags & SEC_LICENCE_NEG)
{
licence_process(s);
continue;
}
if (sec_flags & 0x0400) /* SEC_REDIRECT_ENCRYPT */
{
uint8 swapbyte;
in_uint8s(s, 8); /* signature */
sec_decrypt(s->p, 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(s, channel);
*rdpver = 0xff;
return s;
}
return s;
}
return NULL;
}
/* Establish a secure connection */
BOOL
sec_connect(char *server, char *username)
{
struct stream mcs_data;
/* We exchange some RDP data during the MCS-Connect */
mcs_data.size = 512;
mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size);
sec_out_mcs_data(&mcs_data);
if (!mcs_connect(server, &mcs_data, username))
return False;
/* sec_process_mcs_data(&mcs_data); */
if (g_encryption)
sec_establish_key();
xfree(mcs_data.data);
return True;
}
/* Establish a secure connection */
BOOL
sec_reconnect(char *server)
{
struct stream mcs_data;
/* We exchange some RDP data during the MCS-Connect */
mcs_data.size = 512;
mcs_data.p = mcs_data.data = (uint8 *) xmalloc(mcs_data.size);
sec_out_mcs_data(&mcs_data);
if (!mcs_reconnect(server, &mcs_data))
return False;
/* sec_process_mcs_data(&mcs_data); */
if (g_encryption)
sec_establish_key();
xfree(mcs_data.data);
return True;
}
/* Disconnect a connection */
void
sec_disconnect(void)
{
mcs_disconnect();
}
/* reset the state of the sec layer */
void
sec_reset_state(void)
{
g_server_rdp_version = 0;
sec_encrypt_use_count = 0;
sec_decrypt_use_count = 0;
mcs_reset_state();
}
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