trunk/rdesktop/secure.c

/*
   rdesktop: A Remote Desktop Protocol client.
   Protocol services - RDP encryption and licensing
   Copyright (C) Matthew Chapman 1999-2001

   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"

#ifdef WITH_OPENSSL
#include <openssl/rc4.h>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include <openssl/bn.h>
#else
#include "crypto/rc4.h"
#include "crypto/md5.h"
#include "crypto/sha.h"
#include "crypto/bn.h"
#endif

extern char hostname[16];
extern int width;
extern int height;
extern int keylayout;
extern BOOL encryption;
extern BOOL licence_issued;

static int rc4_key_len;
static RC4_KEY rc4_decrypt_key;
static RC4_KEY rc4_encrypt_key;

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_MODULUS_SIZE];

/*
 * General purpose 48-byte transformation, using two 32-byte salts (generally,
 * a client and server salt) and a global salt value used for padding.
 * 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);
        }
}

/*
 * Weaker 16-byte transformation, also using two 32-byte salts, but
 * only using a single round of MD5.
 */
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 a session key and RC4 keys, given client and server randoms */
static void
sec_generate_keys(uint8 *client_key, uint8 *server_key, int rc4_key_size)
{
        uint8 session_key[48];
        uint8 temp_hash[48];
        uint8 input[48];

        /* Construct input data to hash */
        memcpy(input, client_key, 24);
        memcpy(input + 24, server_key, 24);

        /* Generate session key - two rounds of sec_hash_48 */
        sec_hash_48(temp_hash, input, client_key, server_key, 65);
        sec_hash_48(session_key, temp_hash, client_key, server_key, 88);

        /* Store first 16 bytes of session key, for generating signatures */
        memcpy(sec_sign_key, session_key, 16);

        /* Generate RC4 keys */
        sec_hash_16(sec_decrypt_key, &session_key[16], client_key,
                    server_key);
        sec_hash_16(sec_encrypt_key, &session_key[32], client_key,
                    server_key);

        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(("128-bit encryption enabled\n"));
                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 signature hash, 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 - similar to the signing process */
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)
{
        static int use_count;

        if (use_count == 4096)
        {
                sec_update(sec_encrypt_key, sec_encrypt_update_key);
                RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key);
                use_count = 0;
        }

        RC4(&rc4_encrypt_key, length, data, data);
        use_count++;
}

/* Decrypt data using RC4 */
static void
sec_decrypt(uint8 *data, int length)
{
        static int use_count;

        if (use_count == 4096)
        {
                sec_update(sec_decrypt_key, sec_decrypt_update_key);
                RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key);
                use_count = 0;
        }

        RC4(&rc4_decrypt_key, length, data, data);
        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,
                uint8 *modulus, uint8 *exponent)
{
        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);

        BN_CTX_init(&ctx);
        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 (!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 */
void
sec_send(STREAM s, uint32 flags)
{
        int datalen;

        s_pop_layer(s, sec_hdr);
        if (!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(s);
}

/* Transfer the client random to the server */
static void
sec_establish_key()
{
        uint32 length = SEC_MODULUS_SIZE + SEC_PADDING_SIZE;
        uint32 flags = SEC_CLIENT_RANDOM;
        STREAM s;

        s = sec_init(flags, 76);

        out_uint32_le(s, length);
        out_uint8p(s, sec_crypted_random, SEC_MODULUS_SIZE);
        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(hostname);

        out_uint16_be(s, 5);    /* unknown */
        out_uint16_be(s, 0x14);
        out_uint8(s, 0x7c);
        out_uint16_be(s, 1);

        out_uint16_be(s, (158 | 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);   /* "Duca" ?! */
        out_uint16_be(s, (144 | 0x8000));       /* remaining length */

        /* Client information */
        out_uint16_le(s, SEC_TAG_CLI_INFO);
        out_uint16_le(s, 136);  /* length */
        out_uint16_le(s, 1);
        out_uint16_le(s, 8);
        out_uint16_le(s, width);
        out_uint16_le(s, height);
        out_uint16_le(s, 0xca01);
        out_uint16_le(s, 0xaa03);
        out_uint32_le(s, keylayout);
        out_uint32_le(s, 419);  /* client build? we are 419 compatible :-) */

        /* Unicode name of client, padded to 32 bytes */
        rdp_out_unistr(s, hostname, hostlen);
        out_uint8s(s, 30 - hostlen);

        out_uint32_le(s, 4);
        out_uint32(s, 0);
        out_uint32_le(s, 12);
        out_uint8s(s, 64);      /* reserved? 4 + 12 doublewords */

        out_uint16(s, 0xca01);
        out_uint16(s, 0);

        /* Client encryption settings */
        out_uint16_le(s, SEC_TAG_CLI_CRYPT);
        out_uint16(s, 8);       /* length */
        out_uint32_le(s, encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */
        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);
        if (modulus_len != SEC_MODULUS_SIZE + SEC_PADDING_SIZE)
        {
                error("modulus len 0x%x\n", modulus_len);
                return False;
        }

        in_uint8s(s, 8);        /* modulus_bits, unknown */
        in_uint8p(s, *exponent, SEC_EXPONENT_SIZE);
        in_uint8p(s, *modulus, SEC_MODULUS_SIZE);
        in_uint8s(s, SEC_PADDING_SIZE);

        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;
        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 */
        in_uint32_le(s, random_len);
        in_uint32_le(s, rsa_info_len);

        if (random_len != SEC_RANDOM_SIZE)
        {
                error("random len %d\n", random_len);
                return False;
        }

        in_uint8p(s, *server_random, random_len);

        /* RSA info */
        end = s->p + rsa_info_len;
        if (end > s->end)
                return False;

        in_uint8s(s, 12);       /* 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;

                                break;

                        case SEC_TAG_KEYSIG:
                                /* Is this a Microsoft key that we just got? */
                                /* Care factor: zero! */
                                break;

                        default:
                                unimpl("crypt tag 0x%x\n", tag);
                }

                s->p = next_tag;
        }

        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))
                return;

        /* Generate a client random, and hence determine encryption keys */
        generate_random(client_random);
        sec_rsa_encrypt(sec_crypted_random, client_random,
                        SEC_RANDOM_SIZE, modulus, exponent);
        sec_generate_keys(client_random, server_random, rc4_key_size);
}

/* Process connect response data blob */
static void
sec_process_mcs_data(STREAM s)
{
        uint16 tag, length;
        uint8 *next_tag;

        in_uint8s(s, 23);       /* header */

        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:
                        case SEC_TAG_SRV_3:
                                break;

                        case SEC_TAG_SRV_CRYPT:
                                sec_process_crypt_info(s);
                                break;

                        default:
                                unimpl("response tag 0x%x\n", tag);
                }

                s->p = next_tag;
        }
}

/* Receive secure transport packet */
STREAM
sec_recv()
{
        uint32 sec_flags;
        STREAM s;

        while ((s = mcs_recv()) != NULL)
        {
                if (encryption || !licence_issued)
                {
                        in_uint32_le(s, sec_flags);

                        if (sec_flags & SEC_LICENCE_NEG)
                        {
                                licence_process(s);
                                continue;
                        }

                        if (sec_flags & SEC_ENCRYPT)
                        {
                                in_uint8s(s, 8);        /* signature */
                                sec_decrypt(s->p, s->end - s->p);
                        }
                }

                return s;
        }

        return NULL;
}

/* Establish a secure connection */
BOOL
sec_connect(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 = xmalloc(mcs_data.size);
        sec_out_mcs_data(&mcs_data);

        if (!mcs_connect(server, &mcs_data))
                return False;

        sec_process_mcs_data(&mcs_data);
        if (encryption)
                sec_establish_key();
        return True;
}

/* Disconnect a connection */
void
sec_disconnect()
{
        mcs_disconnect();
}
1	matty	10	/*
2			rdesktop: A Remote Desktop Protocol client.
3			Protocol services - RDP encryption and licensing
4	matty	30	Copyright (C) Matthew Chapman 1999-2001
5	matty	10
6			This program is free software; you can redistribute it and/or modify
7			it under the terms of the GNU General Public License as published by
8			the Free Software Foundation; either version 2 of the License, or
9			(at your option) any later version.
10
11			This program is distributed in the hope that it will be useful,
12			but WITHOUT ANY WARRANTY; without even the implied warranty of
13			MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14			GNU General Public License for more details.
15
16			You should have received a copy of the GNU General Public License
17			along with this program; if not, write to the Free Software
18			Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19			*/
20
21			#include "rdesktop.h"
22	matty	32
23			#ifdef WITH_OPENSSL
24			#include <openssl/rc4.h>
25			#include <openssl/md5.h>
26			#include <openssl/sha.h>
27			#include <openssl/bn.h>
28			#else
29	matty	10	#include "crypto/rc4.h"
30			#include "crypto/md5.h"
31			#include "crypto/sha.h"
32	matty	32	#include "crypto/bn.h"
33			#endif
34	matty	10
35			extern char hostname[16];
36			extern int width;
37			extern int height;
38			extern int keylayout;
39	matty	30	extern BOOL encryption;
40	matty	28	extern BOOL licence_issued;
41	matty	10
42			static int rc4_key_len;
43			static RC4_KEY rc4_decrypt_key;
44			static RC4_KEY rc4_encrypt_key;
45
46	matthewc	57	static uint8 sec_sign_key[16];
47	matty	10	static uint8 sec_decrypt_key[16];
48			static uint8 sec_encrypt_key[16];
49	matthewc	57	static uint8 sec_decrypt_update_key[16];
50			static uint8 sec_encrypt_update_key[16];
51			static uint8 sec_crypted_random[SEC_MODULUS_SIZE];
52	matty	10
53			/*
54			* General purpose 48-byte transformation, using two 32-byte salts (generally,
55			* a client and server salt) and a global salt value used for padding.
56			* Both SHA1 and MD5 algorithms are used.
57			*/
58	matty	25	void
59			sec_hash_48(uint8 out, uint8 in, uint8 salt1, uint8 salt2, uint8 salt)
60	matty	10	{
61			uint8 shasig[20];
62			uint8 pad[4];
63			SHA_CTX sha;
64			MD5_CTX md5;
65			int i;
66
67			for (i = 0; i < 3; i++)
68			{
69	matty	24	memset(pad, salt + i, i + 1);
70	matty	10
71			SHA1_Init(&sha);
72	matty	24	SHA1_Update(&sha, pad, i + 1);
73	matty	10	SHA1_Update(&sha, in, 48);
74			SHA1_Update(&sha, salt1, 32);
75			SHA1_Update(&sha, salt2, 32);
76			SHA1_Final(shasig, &sha);
77
78			MD5_Init(&md5);
79			MD5_Update(&md5, in, 48);
80			MD5_Update(&md5, shasig, 20);
81	matty	24	MD5_Final(&out[i * 16], &md5);
82	matty	10	}
83			}
84
85			/*
86			* Weaker 16-byte transformation, also using two 32-byte salts, but
87			* only using a single round of MD5.
88			*/
89	matty	25	void
90			sec_hash_16(uint8 out, uint8 in, uint8 salt1, uint8 salt2)
91	matty	10	{
92			MD5_CTX md5;
93
94			MD5_Init(&md5);
95			MD5_Update(&md5, in, 16);
96			MD5_Update(&md5, salt1, 32);
97			MD5_Update(&md5, salt2, 32);
98			MD5_Final(out, &md5);
99			}
100
101			/* Reduce key entropy from 64 to 40 bits */
102	matty	25	static void
103			sec_make_40bit(uint8 *key)
104	matty	10	{
105			key[0] = 0xd1;
106			key[1] = 0x26;
107			key[2] = 0x9e;
108			}
109
110			/* Generate a session key and RC4 keys, given client and server randoms */
111	matty	25	static void
112			sec_generate_keys(uint8 client_key, uint8 server_key, int rc4_key_size)
113	matty	10	{
114			uint8 session_key[48];
115			uint8 temp_hash[48];
116			uint8 input[48];
117
118			/* Construct input data to hash */
119	matty	24	memcpy(input, client_key, 24);
120			memcpy(input + 24, server_key, 24);
121	matty	10
122			/* Generate session key - two rounds of sec_hash_48 */
123	matty	24	sec_hash_48(temp_hash, input, client_key, server_key, 65);
124	matty	10	sec_hash_48(session_key, temp_hash, client_key, server_key, 88);
125
126	matthewc	57	/* Store first 16 bytes of session key, for generating signatures */
127			memcpy(sec_sign_key, session_key, 16);
128	matty	10
129			/* Generate RC4 keys */
130	matty	24	sec_hash_16(sec_decrypt_key, &session_key[16], client_key,
131			server_key);
132			sec_hash_16(sec_encrypt_key, &session_key[32], client_key,
133			server_key);
134	matty	10
135			if (rc4_key_size == 1)
136			{
137	matty	30	DEBUG(("40-bit encryption enabled\n"));
138	matty	10	sec_make_40bit(sec_sign_key);
139			sec_make_40bit(sec_decrypt_key);
140			sec_make_40bit(sec_encrypt_key);
141			rc4_key_len = 8;
142			}
143			else
144			{
145	matty	30	DEBUG(("128-bit encryption enabled\n"));
146	matty	10	rc4_key_len = 16;
147			}
148
149	matthewc	57	/* Save initial RC4 keys as update keys */
150			memcpy(sec_decrypt_update_key, sec_decrypt_key, 16);
151			memcpy(sec_encrypt_update_key, sec_encrypt_key, 16);
152	matty	10
153			/* Initialise RC4 state arrays */
154			RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key);
155			RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key);
156			}
157
158	matty	24	static uint8 pad_54[40] = {
159			54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
160	matty	25	54, 54, 54,
161	matty	24	54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54,
162	matty	25	54, 54, 54
163	matty	10	};
164
165	matty	24	static uint8 pad_92[48] = {
166			92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
167	matty	25	92, 92, 92, 92, 92, 92, 92,
168	matty	24	92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92, 92,
169	matty	25	92, 92, 92, 92, 92, 92, 92
170	matty	10	};
171
172			/* Output a uint32 into a buffer (little-endian) */
173	matty	25	void
174			buf_out_uint32(uint8 *buffer, uint32 value)
175	matty	10	{
176			buffer[0] = (value) & 0xff;
177			buffer[1] = (value >> 8) & 0xff;
178			buffer[2] = (value >> 16) & 0xff;
179			buffer[3] = (value >> 24) & 0xff;
180			}
181
182			/* Generate a signature hash, using a combination of SHA1 and MD5 */
183	matty	25	void
184	matthewc	61	sec_sign(uint8 signature, int siglen, uint8 session_key, int keylen,
185	matty	25	uint8 *data, int datalen)
186	matty	10	{
187			uint8 shasig[20];
188			uint8 md5sig[16];
189			uint8 lenhdr[4];
190			SHA_CTX sha;
191			MD5_CTX md5;
192
193	matty	24	buf_out_uint32(lenhdr, datalen);
194	matty	10
195			SHA1_Init(&sha);
196	matthewc	61	SHA1_Update(&sha, session_key, keylen);
197	matty	10	SHA1_Update(&sha, pad_54, 40);
198			SHA1_Update(&sha, lenhdr, 4);
199			SHA1_Update(&sha, data, datalen);
200			SHA1_Final(shasig, &sha);
201
202			MD5_Init(&md5);
203	matthewc	61	MD5_Update(&md5, session_key, keylen);
204	matty	10	MD5_Update(&md5, pad_92, 48);
205			MD5_Update(&md5, shasig, 20);
206			MD5_Final(md5sig, &md5);
207
208	matthewc	61	memcpy(signature, md5sig, siglen);
209	matty	10	}
210
211			/* Update an encryption key - similar to the signing process */
212	matty	25	static void
213			sec_update(uint8 key, uint8 update_key)
214	matty	10	{
215			uint8 shasig[20];
216			SHA_CTX sha;
217			MD5_CTX md5;
218			RC4_KEY update;
219
220			SHA1_Init(&sha);
221	matthewc	57	SHA1_Update(&sha, update_key, rc4_key_len);
222	matty	10	SHA1_Update(&sha, pad_54, 40);
223	matthewc	57	SHA1_Update(&sha, key, rc4_key_len);
224	matty	10	SHA1_Final(shasig, &sha);
225
226			MD5_Init(&md5);
227	matthewc	57	MD5_Update(&md5, update_key, rc4_key_len);
228	matty	10	MD5_Update(&md5, pad_92, 48);
229			MD5_Update(&md5, shasig, 20);
230			MD5_Final(key, &md5);
231
232			RC4_set_key(&update, rc4_key_len, key);
233			RC4(&update, rc4_key_len, key, key);
234
235			if (rc4_key_len == 8)
236			sec_make_40bit(key);
237			}
238
239			/* Encrypt data using RC4 */
240	matty	25	static void
241			sec_encrypt(uint8 *data, int length)
242	matty	10	{
243			static int use_count;
244
245			if (use_count == 4096)
246			{
247			sec_update(sec_encrypt_key, sec_encrypt_update_key);
248			RC4_set_key(&rc4_encrypt_key, rc4_key_len, sec_encrypt_key);
249			use_count = 0;
250			}
251
252			RC4(&rc4_encrypt_key, length, data, data);
253			use_count++;
254			}
255
256			/* Decrypt data using RC4 */
257	matty	25	static void
258			sec_decrypt(uint8 *data, int length)
259	matty	10	{
260			static int use_count;
261
262			if (use_count == 4096)
263			{
264			sec_update(sec_decrypt_key, sec_decrypt_update_key);
265			RC4_set_key(&rc4_decrypt_key, rc4_key_len, sec_decrypt_key);
266			use_count = 0;
267			}
268
269			RC4(&rc4_decrypt_key, length, data, data);
270			use_count++;
271			}
272
273	matty	25	static void
274	matty	32	reverse(uint8 *p, int len)
275	matty	10	{
276			int i, j;
277	matty	32	uint8 temp;
278	matty	10
279	matty	32	for (i = 0, j = len-1; i < j; i++, j--)
280	matty	10	{
281	matty	32	temp = p[i];
282			p[i] = p[j];
283			p[j] = temp;
284	matty	10	}
285			}
286
287			/* Perform an RSA public key encryption operation */
288	matty	25	static void
289			sec_rsa_encrypt(uint8 out, uint8 in, int len,
290			uint8 modulus, uint8 exponent)
291	matty	10	{
292	matty	32	BN_CTX ctx;
293			BIGNUM mod, exp, x, y;
294			uint8 inr[SEC_MODULUS_SIZE];
295			int outlen;
296	matty	10
297	matty	32	reverse(modulus, SEC_MODULUS_SIZE);
298			reverse(exponent, SEC_EXPONENT_SIZE);
299			memcpy(inr, in, len);
300			reverse(inr, len);
301	matty	10
302	matty	32	BN_CTX_init(&ctx);
303			BN_init(&mod);
304			BN_init(&exp);
305			BN_init(&x);
306			BN_init(&y);
307
308			BN_bin2bn(modulus, SEC_MODULUS_SIZE, &mod);
309			BN_bin2bn(exponent, SEC_EXPONENT_SIZE, &exp);
310			BN_bin2bn(inr, len, &x);
311			BN_mod_exp(&y, &x, &exp, &mod, &ctx);
312			outlen = BN_bn2bin(&y, out);
313			reverse(out, outlen);
314			if (outlen < SEC_MODULUS_SIZE)
315			memset(out+outlen, 0, SEC_MODULUS_SIZE-outlen);
316
317			BN_free(&y);
318			BN_clear_free(&x);
319			BN_free(&exp);
320			BN_free(&mod);
321			BN_CTX_free(&ctx);
322	matty	10	}
323
324			/* Initialise secure transport packet */
325	matty	25	STREAM
326			sec_init(uint32 flags, int maxlen)
327	matty	10	{
328			int hdrlen;
329			STREAM s;
330
331	matty	28	if (!licence_issued)
332			hdrlen = (flags & SEC_ENCRYPT) ? 12 : 4;
333			else
334			hdrlen = (flags & SEC_ENCRYPT) ? 12 : 0;
335	matty	24	s = mcs_init(maxlen + hdrlen);
336	matty	10	s_push_layer(s, sec_hdr, hdrlen);
337
338			return s;
339			}
340
341			/* Transmit secure transport packet */
342	matty	25	void
343			sec_send(STREAM s, uint32 flags)
344	matty	10	{
345			int datalen;
346
347			s_pop_layer(s, sec_hdr);
348	matty	28	if (!licence_issued \|\| (flags & SEC_ENCRYPT))
349			out_uint32_le(s, flags);
350	matty	10
351			if (flags & SEC_ENCRYPT)
352			{
353			flags &= ~SEC_ENCRYPT;
354			datalen = s->end - s->p - 8;
355
356	matty	30	#if WITH_DEBUG
357			DEBUG(("Sending encrypted packet:\n"));
358	matty	24	hexdump(s->p + 8, datalen);
359	matty	10	#endif
360
361	matthewc	61	sec_sign(s->p, 8, sec_sign_key, rc4_key_len, s->p + 8, datalen);
362	matty	24	sec_encrypt(s->p + 8, datalen);
363	matty	10	}
364
365			mcs_send(s);
366			}
367
368			/* Transfer the client random to the server */
369	matty	25	static void
370			sec_establish_key()
371	matty	10	{
372			uint32 length = SEC_MODULUS_SIZE + SEC_PADDING_SIZE;
373			uint32 flags = SEC_CLIENT_RANDOM;
374			STREAM s;
375
376			s = sec_init(flags, 76);
377
378			out_uint32_le(s, length);
379			out_uint8p(s, sec_crypted_random, SEC_MODULUS_SIZE);
380			out_uint8s(s, SEC_PADDING_SIZE);
381
382			s_mark_end(s);
383			sec_send(s, flags);
384			}
385
386			/* Output connect initial data blob */
387	matty	25	static void
388			sec_out_mcs_data(STREAM s)
389	matty	10	{
390			int hostlen = 2 * strlen(hostname);
391
392			out_uint16_be(s, 5); /* unknown */
393			out_uint16_be(s, 0x14);
394			out_uint8(s, 0x7c);
395			out_uint16_be(s, 1);
396
397	matty	24	out_uint16_be(s, (158 \| 0x8000)); /* remaining length */
398	matty	10
399			out_uint16_be(s, 8); /* length? */
400			out_uint16_be(s, 16);
401			out_uint8(s, 0);
402			out_uint16_le(s, 0xc001);
403			out_uint8(s, 0);
404
405	matty	24	out_uint32_le(s, 0x61637544); /* "Duca" ?! */
406			out_uint16_be(s, (144 \| 0x8000)); /* remaining length */
407	matty	10
408			/* Client information */
409			out_uint16_le(s, SEC_TAG_CLI_INFO);
410			out_uint16_le(s, 136); /* length */
411			out_uint16_le(s, 1);
412			out_uint16_le(s, 8);
413			out_uint16_le(s, width);
414			out_uint16_le(s, height);
415			out_uint16_le(s, 0xca01);
416			out_uint16_le(s, 0xaa03);
417			out_uint32_le(s, keylayout);
418	matty	24	out_uint32_le(s, 419); /* client build? we are 419 compatible :-) */
419	matty	10
420			/* Unicode name of client, padded to 32 bytes */
421			rdp_out_unistr(s, hostname, hostlen);
422	matty	24	out_uint8s(s, 30 - hostlen);
423	matty	10
424			out_uint32_le(s, 4);
425			out_uint32(s, 0);
426			out_uint32_le(s, 12);
427	matty	24	out_uint8s(s, 64); /* reserved? 4 + 12 doublewords */
428	matty	10
429			out_uint16(s, 0xca01);
430			out_uint16(s, 0);
431
432			/* Client encryption settings */
433			out_uint16_le(s, SEC_TAG_CLI_CRYPT);
434			out_uint16(s, 8); /* length */
435	matthewc	57	out_uint32_le(s, encryption ? 0x3 : 0); /* encryption supported, 128-bit supported */
436	matty	10	s_mark_end(s);
437			}
438
439			/* Parse a public key structure */
440	matty	25	static BOOL
441			sec_parse_public_key(STREAM s, uint8 modulus, uint8 exponent)
442	matty	10	{
443			uint32 magic, modulus_len;
444
445			in_uint32_le(s, magic);
446			if (magic != SEC_RSA_MAGIC)
447			{
448	matty	30	error("RSA magic 0x%x\n", magic);
449	matty	10	return False;
450			}
451
452			in_uint32_le(s, modulus_len);
453			if (modulus_len != SEC_MODULUS_SIZE + SEC_PADDING_SIZE)
454			{
455	matty	30	error("modulus len 0x%x\n", modulus_len);
456	matty	10	return False;
457			}
458
459	matty	24	in_uint8s(s, 8); /* modulus_bits, unknown */
460	matty	10	in_uint8p(s, *exponent, SEC_EXPONENT_SIZE);
461			in_uint8p(s, *modulus, SEC_MODULUS_SIZE);
462			in_uint8s(s, SEC_PADDING_SIZE);
463
464			return s_check(s);
465			}
466
467			/* Parse a crypto information structure */
468	matty	25	static BOOL
469			sec_parse_crypt_info(STREAM s, uint32 *rc4_key_size,
470			uint8 server_random, uint8 modulus, uint8 **exponent)
471	matty	10	{
472			uint32 crypt_level, random_len, rsa_info_len;
473			uint16 tag, length;
474			uint8 next_tag, end;
475
476	matty	24	in_uint32_le(s, rc4_key_size); / 1 = 40-bit, 2 = 128-bit */
477			in_uint32_le(s, crypt_level); /* 1 = low, 2 = medium, 3 = high */
478	matty	10	in_uint32_le(s, random_len);
479			in_uint32_le(s, rsa_info_len);
480
481			if (random_len != SEC_RANDOM_SIZE)
482			{
483	matty	30	error("random len %d\n", random_len);
484	matty	10	return False;
485			}
486
487			in_uint8p(s, *server_random, random_len);
488
489			/* RSA info */
490			end = s->p + rsa_info_len;
491			if (end > s->end)
492			return False;
493
494	matty	24	in_uint8s(s, 12); /* unknown */
495	matty	10
496			while (s->p < end)
497			{
498			in_uint16_le(s, tag);
499			in_uint16_le(s, length);
500
501			next_tag = s->p + length;
502
503			switch (tag)
504			{
505			case SEC_TAG_PUBKEY:
506	matty	24	if (!sec_parse_public_key
507			(s, modulus, exponent))
508	matty	10	return False;
509
510			break;
511
512			case SEC_TAG_KEYSIG:
513			/* Is this a Microsoft key that we just got? */
514			/* Care factor: zero! */
515			break;
516
517			default:
518	matty	30	unimpl("crypt tag 0x%x\n", tag);
519	matty	10	}
520
521			s->p = next_tag;
522			}
523
524			return s_check_end(s);
525			}
526
527			/* Process crypto information blob */
528	matty	25	static void
529			sec_process_crypt_info(STREAM s)
530	matty	10	{
531			uint8 server_random, modulus, *exponent;
532			uint8 client_random[SEC_RANDOM_SIZE];
533			uint32 rc4_key_size;
534
535			if (!sec_parse_crypt_info(s, &rc4_key_size, &server_random,
536	matty	24	&modulus, &exponent))
537	matty	10	return;
538
539			/* Generate a client random, and hence determine encryption keys */
540			generate_random(client_random);
541			sec_rsa_encrypt(sec_crypted_random, client_random,
542	matty	24	SEC_RANDOM_SIZE, modulus, exponent);
543	matty	10	sec_generate_keys(client_random, server_random, rc4_key_size);
544			}
545
546			/* Process connect response data blob */
547	matty	25	static void
548			sec_process_mcs_data(STREAM s)
549	matty	10	{
550			uint16 tag, length;
551			uint8 *next_tag;
552
553	matty	24	in_uint8s(s, 23); /* header */
554	matty	10
555			while (s->p < s->end)
556			{
557			in_uint16_le(s, tag);
558			in_uint16_le(s, length);
559
560			if (length <= 4)
561			return;
562
563			next_tag = s->p + length - 4;
564
565			switch (tag)
566			{
567			case SEC_TAG_SRV_INFO:
568			case SEC_TAG_SRV_3:
569			break;
570
571			case SEC_TAG_SRV_CRYPT:
572			sec_process_crypt_info(s);
573			break;
574
575			default:
576	matty	30	unimpl("response tag 0x%x\n", tag);
577	matty	10	}
578
579			s->p = next_tag;
580			}
581			}
582
583			/* Receive secure transport packet */
584	matty	25	STREAM
585			sec_recv()
586	matty	10	{
587			uint32 sec_flags;
588			STREAM s;
589
590			while ((s = mcs_recv()) != NULL)
591			{
592	matty	30	if (encryption \|\| !licence_issued)
593	matty	10	{
594	matty	28	in_uint32_le(s, sec_flags);
595	matty	10
596	matty	28	if (sec_flags & SEC_LICENCE_NEG)
597			{
598			licence_process(s);
599			continue;
600			}
601
602			if (sec_flags & SEC_ENCRYPT)
603			{
604			in_uint8s(s, 8); /* signature */
605			sec_decrypt(s->p, s->end - s->p);
606			}
607	matty	10	}
608
609			return s;
610			}
611
612			return NULL;
613			}
614
615			/* Establish a secure connection */
616	matty	25	BOOL
617			sec_connect(char *server)
618	matty	10	{
619			struct stream mcs_data;
620
621			/* We exchange some RDP data during the MCS-Connect */
622			mcs_data.size = 512;
623			mcs_data.p = mcs_data.data = xmalloc(mcs_data.size);
624			sec_out_mcs_data(&mcs_data);
625
626			if (!mcs_connect(server, &mcs_data))
627			return False;
628
629			sec_process_mcs_data(&mcs_data);
630	matty	30	if (encryption)
631	matty	28	sec_establish_key();
632	matty	10	return True;
633			}
634
635			/* Disconnect a connection */
636	matty	25	void
637			sec_disconnect()
638	matty	10	{
639			mcs_disconnect();
640			}