adding rdesktop files

1 files changed, 981 insertions, 0 deletions

diff --git a/uirdesktop/secure.c b/uirdesktop/secure.c
new file mode 100644
index 00000000..0d22ecc3
--- /dev/null
+++ b/uirdesktop/secure.c
@@ -0,0 +1,981 @@
+/* -*- 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>
+
+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 RC4_KEY rc4_decrypt_key;
+static RC4_KEY rc4_encrypt_key;
+static RSA *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];
+	SHA_CTX sha;
+	MD5_CTX md5;
+	int i;
+
+	for (i = 0; i < 3; i++)
+	{
+		memset(pad, salt + i, i + 1);
+
+		SHA1_Init(&sha);
+		SHA1_Update(&sha, pad, i + 1);
+		SHA1_Update(&sha, in, 48);
+		SHA1_Update(&sha, salt1, 32);
+		SHA1_Update(&sha, salt2, 32);
+		SHA1_Final(shasig, &sha);
+
+		MD5_Init(&md5);
+		MD5_Update(&md5, in, 48);
+		MD5_Update(&md5, shasig, 20);
+		MD5_Final(&out[i * 16], &md5);
+	}
+}
+
+/*
+ * 16-byte transformation used to generate export keys (6.2.2).
+ */
+void
+sec_hash_16(uint8 * out, uint8 * in, uint8 * salt1, uint8 * salt2)
+{
+	MD5_CTX md5;
+
+	MD5_Init(&md5);
+	MD5_Update(&md5, in, 16);
+	MD5_Update(&md5, salt1, 32);
+	MD5_Update(&md5, salt2, 32);
+	MD5_Final(out, &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 */
+	RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key);
+	RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key);
+}
+
+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];
+	SHA_CTX sha;
+	MD5_CTX md5;
+
+	buf_out_uint32(lenhdr, datalen);
+
+	SHA1_Init(&sha);
+	SHA1_Update(&sha, session_key, keylen);
+	SHA1_Update(&sha, pad_54, 40);
+	SHA1_Update(&sha, lenhdr, 4);
+	SHA1_Update(&sha, data, datalen);
+	SHA1_Final(shasig, &sha);
+
+	MD5_Init(&md5);
+	MD5_Update(&md5, session_key, keylen);
+	MD5_Update(&md5, pad_92, 48);
+	MD5_Update(&md5, shasig, 20);
+	MD5_Final(md5sig, &md5);
+
+	memcpy(signature, md5sig, siglen);
+}
+
+/* Update an encryption key */
+static void
+sec_update(uint8 * key, uint8 * update_key)
+{
+	uint8 shasig[20];
+	SHA_CTX sha;
+	MD5_CTX md5;
+	RC4_KEY update;
+
+	SHA1_Init(&sha);
+	SHA1_Update(&sha, update_key, rc4_key_len);
+	SHA1_Update(&sha, pad_54, 40);
+	SHA1_Update(&sha, key, rc4_key_len);
+	SHA1_Final(shasig, &sha);
+
+	MD5_Init(&md5);
+	MD5_Update(&md5, update_key, rc4_key_len);
+	MD5_Update(&md5, pad_92, 48);
+	MD5_Update(&md5, shasig, 20);
+	MD5_Final(key, &md5);
+
+	RC4_set_key(&update, rc4_key_len, key);
+	RC4(&update, rc4_key_len, key, key);
+
+	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);
+		RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key);
+		sec_encrypt_use_count = 0;
+	}
+
+	RC4(&rc4_encrypt_key, length, data, data);
+	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);
+		RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key);
+		sec_decrypt_use_count = 0;
+	}
+
+	RC4(&rc4_decrypt_key, length, data, data);
+	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)
+{
+	BN_CTX *ctx;
+	BIGNUM mod, exp, x, y;
+	uint8 inr[SEC_MAX_MODULUS_SIZE];
+	int outlen;
+
+	reverse(modulus, 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, 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 < modulus_size)
+		memset(out + outlen, 0, 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;
+
+#if 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);
+}
+
+static BOOL
+sec_parse_x509_key(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;
+	}
+
+	server_public_key = RSAPublicKey_dup((RSA *) epk->pkey.ptr);
+	EVP_PKEY_free(epk);
+
+	server_public_key_len = RSA_size(server_public_key);
+	if ((server_public_key_len < 64) || (server_public_key_len > SEC_MAX_MODULUS_SIZE))
+	{
+		error("Bad server public key size (%u bits)\n", server_public_key_len*8);
+		return False;
+	}
+
+	return True;
+}
+
+
+/* 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
+	{
+		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 */
+	}
+	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;
+
+	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_random(client_random);
+
+	if (NULL != server_public_key)
+	{			/* Which means we should use 
+				   RDP5-style encryption */
+		uint8 inr[SEC_MAX_MODULUS_SIZE];
+		uint32 padding_len = 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(server_public_key_len,
+				   inr, sec_crypted_random, server_public_key, RSA_NO_PADDING);
+
+		reverse(sec_crypted_random, server_public_key_len);
+
+		RSA_free(server_public_key);
+		server_public_key = NULL;
+	}
+	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();
+}