trunk/rdesktop/licence.c

/*
   rdesktop: A Remote Desktop Protocol client.
   RDP licensing negotiation
   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"
#include "crypto/rc4.h"

extern char username[16];
extern char hostname[16];
extern BOOL licence;

static uint8 licence_key[16];
static uint8 licence_sign_key[16];

BOOL licence_issued = False;

/* Generate a session key and RC4 keys, given client and server randoms */
void
licence_generate_keys(uint8 *client_key, uint8 *server_key, uint8 *client_rsa)
{
        uint8 session_key[48];
        uint8 temp_hash[48];

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

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

        /* Generate RC4 key */
        sec_hash_16(licence_key, &session_key[16], client_key, server_key);
}

/* Send a licence request packet */
static void
licence_send_request(uint8 *client_random, uint8 *rsa_data,
                     char *user, char *host)
{
        uint32 sec_flags = SEC_LICENCE_NEG;
        uint16 userlen = strlen(user) + 1;
        uint16 hostlen = strlen(host) + 1;
        uint16 length = 120 + userlen + hostlen;
        STREAM s;

        s = sec_init(sec_flags, length + 2);

        out_uint16_le(s, LICENCE_TAG_REQUEST);
        out_uint16_le(s, length);

        out_uint32_le(s, 1);
        out_uint32_le(s, 0xff010000);

        out_uint8p(s, client_random, SEC_RANDOM_SIZE);
        out_uint16(s, 0);
        out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
        out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
        out_uint8s(s, SEC_PADDING_SIZE);

        out_uint16(s, LICENCE_TAG_USER);
        out_uint16(s, userlen);
        out_uint8p(s, user, userlen);

        out_uint16(s, LICENCE_TAG_HOST);
        out_uint16(s, hostlen);
        out_uint8p(s, host, hostlen);

        s_mark_end(s);
        sec_send(s, sec_flags);
}

/* Process a licence demand packet */
static void
licence_process_demand(STREAM s)
{
        uint8 null_data[SEC_MODULUS_SIZE];
        uint8 *server_random;

        /* Retrieve the server random from the incoming packet */
        in_uint8p(s, server_random, SEC_RANDOM_SIZE);

        /* We currently use null client keys. This is a bit naughty but, hey,
           the security of licence negotiation isn't exactly paramount. */
        memset(null_data, 0, sizeof(null_data));
        licence_generate_keys(null_data, server_random, null_data);

        /* Send a certificate request back to the server */
        licence_send_request(null_data, null_data, username, hostname);
}

/* Send an authentication response packet */
static void
licence_send_authresp(uint8 *token, uint8 *crypt_hwid, uint8 *signature)
{
        uint32 sec_flags = SEC_LICENCE_NEG;
        uint16 length = 58;
        STREAM s;

        s = sec_init(sec_flags, length + 2);

        out_uint16_le(s, LICENCE_TAG_AUTHRESP);
        out_uint16_le(s, length);

        out_uint16_le(s, 1);
        out_uint16_le(s, LICENCE_TOKEN_SIZE);
        out_uint8p(s, token, LICENCE_TOKEN_SIZE);

        out_uint16_le(s, 1);
        out_uint16_le(s, LICENCE_HWID_SIZE);
        out_uint8p(s, crypt_hwid, LICENCE_HWID_SIZE);

        out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);

        s_mark_end(s);
        sec_send(s, sec_flags);
}

/* Parse an authentication request packet */
static BOOL
licence_parse_authreq(STREAM s, uint8 **token, uint8 **signature)
{
        uint16 tokenlen;

        in_uint8s(s, 6);        /* unknown: f8 3d 15 00 04 f6 */

        in_uint16_le(s, tokenlen);
        if (tokenlen != LICENCE_TOKEN_SIZE)
        {
                error("token len %d\n", tokenlen);
                return False;
        }

        in_uint8p(s, *token, tokenlen);
        in_uint8p(s, *signature, LICENCE_SIGNATURE_SIZE);

        return s_check_end(s);
}

/* Process an authentication request packet */
static void
licence_process_authreq(STREAM s)
{
        uint8 *in_token, *in_sig;
        uint8 out_token[LICENCE_TOKEN_SIZE],
                decrypt_token[LICENCE_TOKEN_SIZE];
        uint8 hwid[LICENCE_HWID_SIZE], crypt_hwid[LICENCE_HWID_SIZE];
        uint8 sealed_buffer[LICENCE_TOKEN_SIZE + LICENCE_HWID_SIZE];
        uint8 out_sig[LICENCE_SIGNATURE_SIZE];
        RC4_KEY crypt_key;

        /* Parse incoming packet and save the encrypted token */
        licence_parse_authreq(s, &in_token, &in_sig);
        memcpy(out_token, in_token, LICENCE_TOKEN_SIZE);

        /* Decrypt the token. It should read TEST in Unicode. */
        RC4_set_key(&crypt_key, 16, licence_key);
        RC4(&crypt_key, LICENCE_TOKEN_SIZE, in_token, decrypt_token);

        /* Construct HWID */
        buf_out_uint32(hwid, 2);
        strncpy(hwid + 4, hostname, LICENCE_HWID_SIZE - 4);

        /* Generate a signature for a buffer of token and HWID */
        memcpy(sealed_buffer, decrypt_token, LICENCE_TOKEN_SIZE);
        memcpy(sealed_buffer + LICENCE_TOKEN_SIZE, hwid, LICENCE_HWID_SIZE);
        sec_sign(out_sig, licence_sign_key, 16,
                 sealed_buffer, sizeof(sealed_buffer));

        /* Deliberately break signature if licencing disabled */
        if (!licence)
                memset(out_sig, 0, sizeof(out_sig));

        /* Now encrypt the HWID */
        RC4_set_key(&crypt_key, 16, licence_key);
        RC4(&crypt_key, LICENCE_HWID_SIZE, hwid, crypt_hwid);

        licence_send_authresp(out_token, crypt_hwid, out_sig);
}

/* Process an licence issue packet */
static void
licence_process_issue(STREAM s)
{
        RC4_KEY crypt_key;
        uint32 length;
        uint16 check;

        in_uint8s(s, 2);        /* 3d 45 - unknown */
        in_uint16_le(s, length);
        if (!s_check_rem(s, length))
                return;

        RC4_set_key(&crypt_key, 16, licence_key);
        RC4(&crypt_key, length, s->p, s->p);

        in_uint16(s, check);
        if (check != 0)
                return;

        licence_issued = True;

        /* We should save the licence here */
}

/* Process a licence packet */
void
licence_process(STREAM s)
{
        uint16 tag;

        in_uint16_le(s, tag);
        in_uint8s(s, 2);        /* length */

        switch (tag)
        {
                case LICENCE_TAG_DEMAND:
                        licence_process_demand(s);
                        break;

                case LICENCE_TAG_AUTHREQ:
                        licence_process_authreq(s);
                        break;

                case LICENCE_TAG_ISSUE:
                        licence_process_issue(s);
                        break;

                case LICENCE_TAG_RESULT:
                        break;

                default:
                        unimpl("licence tag 0x%x\n", tag);
        }
}
1	matty	10	/*
2			rdesktop: A Remote Desktop Protocol client.
3			RDP licensing negotiation
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			#include "crypto/rc4.h"
23
24			extern char username[16];
25			extern char hostname[16];
26			extern BOOL licence;
27
28			static uint8 licence_key[16];
29			static uint8 licence_sign_key[16];
30
31	matty	28	BOOL licence_issued = False;
32
33	matty	10	/* Generate a session key and RC4 keys, given client and server randoms */
34	matty	25	void
35			licence_generate_keys(uint8 client_key, uint8 server_key, uint8 *client_rsa)
36	matty	10	{
37			uint8 session_key[48];
38			uint8 temp_hash[48];
39
40			/* Generate session key - two rounds of sec_hash_48 */
41	matty	24	sec_hash_48(temp_hash, client_rsa, client_key, server_key, 65);
42			sec_hash_48(session_key, temp_hash, server_key, client_key, 65);
43	matty	10
44			/* Store first 16 bytes of session key, for generating signatures */
45	matty	24	memcpy(licence_sign_key, session_key, 16);
46	matty	10
47			/* Generate RC4 key */
48			sec_hash_16(licence_key, &session_key[16], client_key, server_key);
49			}
50
51			/* Send a licence request packet */
52	matty	25	static void
53			licence_send_request(uint8 client_random, uint8 rsa_data,
54			char user, char host)
55	matty	10	{
56			uint32 sec_flags = SEC_LICENCE_NEG;
57			uint16 userlen = strlen(user) + 1;
58			uint16 hostlen = strlen(host) + 1;
59			uint16 length = 120 + userlen + hostlen;
60			STREAM s;
61
62			s = sec_init(sec_flags, length + 2);
63
64			out_uint16_le(s, LICENCE_TAG_REQUEST);
65			out_uint16_le(s, length);
66
67			out_uint32_le(s, 1);
68			out_uint32_le(s, 0xff010000);
69
70			out_uint8p(s, client_random, SEC_RANDOM_SIZE);
71			out_uint16(s, 0);
72			out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
73			out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
74			out_uint8s(s, SEC_PADDING_SIZE);
75
76			out_uint16(s, LICENCE_TAG_USER);
77			out_uint16(s, userlen);
78			out_uint8p(s, user, userlen);
79
80			out_uint16(s, LICENCE_TAG_HOST);
81			out_uint16(s, hostlen);
82			out_uint8p(s, host, hostlen);
83
84			s_mark_end(s);
85			sec_send(s, sec_flags);
86			}
87
88			/* Process a licence demand packet */
89	matty	25	static void
90			licence_process_demand(STREAM s)
91	matty	10	{
92			uint8 null_data[SEC_MODULUS_SIZE];
93			uint8 *server_random;
94
95			/* Retrieve the server random from the incoming packet */
96			in_uint8p(s, server_random, SEC_RANDOM_SIZE);
97
98			/* We currently use null client keys. This is a bit naughty but, hey,
99			the security of licence negotiation isn't exactly paramount. */
100			memset(null_data, 0, sizeof(null_data));
101			licence_generate_keys(null_data, server_random, null_data);
102
103			/* Send a certificate request back to the server */
104			licence_send_request(null_data, null_data, username, hostname);
105			}
106
107			/* Send an authentication response packet */
108	matty	25	static void
109			licence_send_authresp(uint8 token, uint8 crypt_hwid, uint8 *signature)
110	matty	10	{
111			uint32 sec_flags = SEC_LICENCE_NEG;
112			uint16 length = 58;
113			STREAM s;
114
115			s = sec_init(sec_flags, length + 2);
116
117			out_uint16_le(s, LICENCE_TAG_AUTHRESP);
118			out_uint16_le(s, length);
119
120			out_uint16_le(s, 1);
121			out_uint16_le(s, LICENCE_TOKEN_SIZE);
122			out_uint8p(s, token, LICENCE_TOKEN_SIZE);
123
124			out_uint16_le(s, 1);
125			out_uint16_le(s, LICENCE_HWID_SIZE);
126			out_uint8p(s, crypt_hwid, LICENCE_HWID_SIZE);
127
128			out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);
129
130			s_mark_end(s);
131			sec_send(s, sec_flags);
132			}
133
134			/* Parse an authentication request packet */
135	matty	25	static BOOL
136			licence_parse_authreq(STREAM s, uint8 token, uint8 signature)
137	matty	10	{
138			uint16 tokenlen;
139
140	matty	24	in_uint8s(s, 6); /* unknown: f8 3d 15 00 04 f6 */
141	matty	10
142			in_uint16_le(s, tokenlen);
143			if (tokenlen != LICENCE_TOKEN_SIZE)
144			{
145	matty	30	error("token len %d\n", tokenlen);
146	matty	10	return False;
147			}
148
149			in_uint8p(s, *token, tokenlen);
150			in_uint8p(s, *signature, LICENCE_SIGNATURE_SIZE);
151
152			return s_check_end(s);
153			}
154
155			/* Process an authentication request packet */
156	matty	25	static void
157			licence_process_authreq(STREAM s)
158	matty	10	{
159			uint8 in_token, in_sig;
160	matty	24	uint8 out_token[LICENCE_TOKEN_SIZE],
161			decrypt_token[LICENCE_TOKEN_SIZE];
162	matty	10	uint8 hwid[LICENCE_HWID_SIZE], crypt_hwid[LICENCE_HWID_SIZE];
163			uint8 sealed_buffer[LICENCE_TOKEN_SIZE + LICENCE_HWID_SIZE];
164			uint8 out_sig[LICENCE_SIGNATURE_SIZE];
165			RC4_KEY crypt_key;
166
167			/* Parse incoming packet and save the encrypted token */
168			licence_parse_authreq(s, &in_token, &in_sig);
169			memcpy(out_token, in_token, LICENCE_TOKEN_SIZE);
170
171			/* Decrypt the token. It should read TEST in Unicode. */
172			RC4_set_key(&crypt_key, 16, licence_key);
173			RC4(&crypt_key, LICENCE_TOKEN_SIZE, in_token, decrypt_token);
174
175			/* Construct HWID */
176			buf_out_uint32(hwid, 2);
177			strncpy(hwid + 4, hostname, LICENCE_HWID_SIZE - 4);
178
179			/* Generate a signature for a buffer of token and HWID */
180			memcpy(sealed_buffer, decrypt_token, LICENCE_TOKEN_SIZE);
181			memcpy(sealed_buffer + LICENCE_TOKEN_SIZE, hwid, LICENCE_HWID_SIZE);
182			sec_sign(out_sig, licence_sign_key, 16,
183	matty	24	sealed_buffer, sizeof(sealed_buffer));
184	matty	10
185			/* Deliberately break signature if licencing disabled */
186			if (!licence)
187			memset(out_sig, 0, sizeof(out_sig));
188
189			/* Now encrypt the HWID */
190			RC4_set_key(&crypt_key, 16, licence_key);
191			RC4(&crypt_key, LICENCE_HWID_SIZE, hwid, crypt_hwid);
192
193			licence_send_authresp(out_token, crypt_hwid, out_sig);
194			}
195
196			/* Process an licence issue packet */
197	matty	25	static void
198			licence_process_issue(STREAM s)
199	matty	10	{
200			RC4_KEY crypt_key;
201			uint32 length;
202			uint16 check;
203
204	matty	24	in_uint8s(s, 2); /* 3d 45 - unknown */
205	matty	10	in_uint16_le(s, length);
206			if (!s_check_rem(s, length))
207			return;
208
209			RC4_set_key(&crypt_key, 16, licence_key);
210			RC4(&crypt_key, length, s->p, s->p);
211
212			in_uint16(s, check);
213			if (check != 0)
214			return;
215
216	matty	28	licence_issued = True;
217
218	matty	10	/* We should save the licence here */
219			}
220
221			/* Process a licence packet */
222	matty	25	void
223			licence_process(STREAM s)
224	matty	10	{
225			uint16 tag;
226
227			in_uint16_le(s, tag);
228	matty	24	in_uint8s(s, 2); /* length */
229	matty	10
230			switch (tag)
231			{
232			case LICENCE_TAG_DEMAND:
233			licence_process_demand(s);
234			break;
235
236			case LICENCE_TAG_AUTHREQ:
237			licence_process_authreq(s);
238			break;
239
240			case LICENCE_TAG_ISSUE:
241			licence_process_issue(s);
242			break;
243
244			case LICENCE_TAG_RESULT:
245			break;
246
247			default:
248	matty	30	unimpl("licence tag 0x%x\n", tag);
249	matty	10	}
250			}