1 | /* -*- c-basic-offset: 8 -*-
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2 | rdesktop: A Remote Desktop Protocol client.
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3 | RDP licensing negotiation
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4 | Copyright (C) Matthew Chapman 1999-2005
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5 |
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6 | This program is free software; you can redistribute it and/or modify
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7 | it under the terms of the GNU General Public License as published by
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8 | the Free Software Foundation; either version 2 of the License, or
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9 | (at your option) any later version.
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10 |
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11 | This program is distributed in the hope that it will be useful,
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12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 | GNU General Public License for more details.
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15 |
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16 | You should have received a copy of the GNU General Public License
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17 | along with this program; if not, write to the Free Software
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18 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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19 | */
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20 |
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21 | #include "rdesktop.h"
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22 | #include <openssl/rc4.h>
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23 |
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24 | extern char g_username[64];
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25 | extern char g_hostname[16];
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26 |
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27 | static uint8 g_licence_key[16];
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28 | static uint8 g_licence_sign_key[16];
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29 |
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30 | BOOL g_licence_issued = False;
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31 |
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32 | /* Generate a session key and RC4 keys, given client and server randoms */
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33 | static void
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34 | licence_generate_keys(uint8 * client_random, uint8 * server_random, uint8 * pre_master_secret)
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35 | {
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36 | uint8 master_secret[48];
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37 | uint8 key_block[48];
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38 |
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39 | /* Generate master secret and then key material */
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40 | sec_hash_48(master_secret, pre_master_secret, client_random, server_random, 'A');
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41 | sec_hash_48(key_block, master_secret, server_random, client_random, 'A');
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42 |
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43 | /* Store first 16 bytes of session key as MAC secret */
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44 | memcpy(g_licence_sign_key, key_block, 16);
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45 |
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46 | /* Generate RC4 key from next 16 bytes */
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47 | sec_hash_16(g_licence_key, &key_block[16], client_random, server_random);
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48 | }
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49 |
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50 | static void
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51 | licence_generate_hwid(uint8 * hwid)
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52 | {
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53 | buf_out_uint32(hwid, 2);
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54 | strncpy((char *) (hwid + 4), g_hostname, LICENCE_HWID_SIZE - 4);
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55 | }
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56 |
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57 | /* Present an existing licence to the server */
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58 | static void
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59 | licence_present(uint8 * client_random, uint8 * rsa_data,
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60 | uint8 * licence_data, int licence_size, uint8 * hwid, uint8 * signature)
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61 | {
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62 | uint32 sec_flags = SEC_LICENCE_NEG;
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63 | uint16 length =
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64 | 16 + SEC_RANDOM_SIZE + SEC_MODULUS_SIZE + SEC_PADDING_SIZE +
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65 | licence_size + LICENCE_HWID_SIZE + LICENCE_SIGNATURE_SIZE;
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66 | STREAM s;
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67 |
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68 | s = sec_init(sec_flags, length + 4);
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69 |
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70 | out_uint8(s, LICENCE_TAG_PRESENT);
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71 | out_uint8(s, 2); /* version */
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72 | out_uint16_le(s, length);
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73 |
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74 | out_uint32_le(s, 1);
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75 | out_uint16(s, 0);
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76 | out_uint16_le(s, 0x0201);
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77 |
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78 | out_uint8p(s, client_random, SEC_RANDOM_SIZE);
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79 | out_uint16(s, 0);
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80 | out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
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81 | out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
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82 | out_uint8s(s, SEC_PADDING_SIZE);
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83 |
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84 | out_uint16_le(s, 1);
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85 | out_uint16_le(s, licence_size);
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86 | out_uint8p(s, licence_data, licence_size);
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87 |
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88 | out_uint16_le(s, 1);
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89 | out_uint16_le(s, LICENCE_HWID_SIZE);
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90 | out_uint8p(s, hwid, LICENCE_HWID_SIZE);
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91 |
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92 | out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);
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93 |
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94 | s_mark_end(s);
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95 | sec_send(s, sec_flags);
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96 | }
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97 |
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98 | /* Send a licence request packet */
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99 | static void
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100 | licence_send_request(uint8 * client_random, uint8 * rsa_data, char *user, char *host)
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101 | {
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102 | uint32 sec_flags = SEC_LICENCE_NEG;
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103 | uint16 userlen = strlen(user) + 1;
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104 | uint16 hostlen = strlen(host) + 1;
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105 | uint16 length = 128 + userlen + hostlen;
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106 | STREAM s;
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107 |
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108 | s = sec_init(sec_flags, length + 2);
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109 |
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110 | out_uint8(s, LICENCE_TAG_REQUEST);
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111 | out_uint8(s, 2); /* version */
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112 | out_uint16_le(s, length);
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113 |
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114 | out_uint32_le(s, 1);
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115 | out_uint16(s, 0);
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116 | out_uint16_le(s, 0xff01);
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117 |
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118 | out_uint8p(s, client_random, SEC_RANDOM_SIZE);
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119 | out_uint16(s, 0);
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120 | out_uint16_le(s, (SEC_MODULUS_SIZE + SEC_PADDING_SIZE));
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121 | out_uint8p(s, rsa_data, SEC_MODULUS_SIZE);
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122 | out_uint8s(s, SEC_PADDING_SIZE);
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123 |
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124 | out_uint16_le(s, LICENCE_TAG_USER);
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125 | out_uint16_le(s, userlen);
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126 | out_uint8p(s, user, userlen);
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127 |
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128 | out_uint16_le(s, LICENCE_TAG_HOST);
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129 | out_uint16_le(s, hostlen);
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130 | out_uint8p(s, host, hostlen);
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131 |
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132 | s_mark_end(s);
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133 | sec_send(s, sec_flags);
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134 | }
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135 |
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136 | /* Process a licence demand packet */
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137 | static void
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138 | licence_process_demand(STREAM s)
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139 | {
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140 | uint8 null_data[SEC_MODULUS_SIZE];
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141 | uint8 *server_random;
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142 | uint8 signature[LICENCE_SIGNATURE_SIZE];
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143 | uint8 hwid[LICENCE_HWID_SIZE];
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144 | uint8 *licence_data;
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145 | int licence_size;
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146 | RC4_KEY crypt_key;
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147 |
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148 | /* Retrieve the server random from the incoming packet */
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149 | in_uint8p(s, server_random, SEC_RANDOM_SIZE);
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150 |
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151 | /* We currently use null client keys. This is a bit naughty but, hey,
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152 | the security of licence negotiation isn't exactly paramount. */
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153 | memset(null_data, 0, sizeof(null_data));
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154 | licence_generate_keys(null_data, server_random, null_data);
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155 |
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156 | licence_size = load_licence(&licence_data);
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157 | if (licence_size > 0)
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158 | {
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159 | /* Generate a signature for the HWID buffer */
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160 | licence_generate_hwid(hwid);
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161 | sec_sign(signature, 16, g_licence_sign_key, 16, hwid, sizeof(hwid));
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162 |
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163 | /* Now encrypt the HWID */
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164 | RC4_set_key(&crypt_key, 16, g_licence_key);
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165 | RC4(&crypt_key, sizeof(hwid), hwid, hwid);
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166 |
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167 | licence_present(null_data, null_data, licence_data, licence_size, hwid, signature);
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168 | xfree(licence_data);
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169 | return;
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170 | }
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171 |
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172 | licence_send_request(null_data, null_data, g_username, g_hostname);
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173 | }
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174 |
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175 | /* Send an authentication response packet */
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176 | static void
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177 | licence_send_authresp(uint8 * token, uint8 * crypt_hwid, uint8 * signature)
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178 | {
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179 | uint32 sec_flags = SEC_LICENCE_NEG;
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180 | uint16 length = 58;
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181 | STREAM s;
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182 |
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183 | s = sec_init(sec_flags, length + 2);
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184 |
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185 | out_uint8(s, LICENCE_TAG_AUTHRESP);
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186 | out_uint8(s, 2); /* version */
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187 | out_uint16_le(s, length);
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188 |
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189 | out_uint16_le(s, 1);
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190 | out_uint16_le(s, LICENCE_TOKEN_SIZE);
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191 | out_uint8p(s, token, LICENCE_TOKEN_SIZE);
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192 |
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193 | out_uint16_le(s, 1);
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194 | out_uint16_le(s, LICENCE_HWID_SIZE);
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195 | out_uint8p(s, crypt_hwid, LICENCE_HWID_SIZE);
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196 |
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197 | out_uint8p(s, signature, LICENCE_SIGNATURE_SIZE);
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198 |
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199 | s_mark_end(s);
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200 | sec_send(s, sec_flags);
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201 | }
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202 |
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203 | /* Parse an authentication request packet */
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204 | static BOOL
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205 | licence_parse_authreq(STREAM s, uint8 ** token, uint8 ** signature)
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206 | {
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207 | uint16 tokenlen;
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208 |
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209 | in_uint8s(s, 6); /* unknown: f8 3d 15 00 04 f6 */
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210 |
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211 | in_uint16_le(s, tokenlen);
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212 | if (tokenlen != LICENCE_TOKEN_SIZE)
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213 | {
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214 | error("token len %d\n", tokenlen);
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215 | return False;
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216 | }
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217 |
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218 | in_uint8p(s, *token, tokenlen);
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219 | in_uint8p(s, *signature, LICENCE_SIGNATURE_SIZE);
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220 |
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221 | return s_check_end(s);
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222 | }
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223 |
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224 | /* Process an authentication request packet */
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225 | static void
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226 | licence_process_authreq(STREAM s)
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227 | {
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228 | uint8 *in_token = NULL, *in_sig;
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229 | uint8 out_token[LICENCE_TOKEN_SIZE], decrypt_token[LICENCE_TOKEN_SIZE];
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230 | uint8 hwid[LICENCE_HWID_SIZE], crypt_hwid[LICENCE_HWID_SIZE];
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231 | uint8 sealed_buffer[LICENCE_TOKEN_SIZE + LICENCE_HWID_SIZE];
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232 | uint8 out_sig[LICENCE_SIGNATURE_SIZE];
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233 | RC4_KEY crypt_key;
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234 |
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235 | /* Parse incoming packet and save the encrypted token */
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236 | licence_parse_authreq(s, &in_token, &in_sig);
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237 | memcpy(out_token, in_token, LICENCE_TOKEN_SIZE);
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238 |
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239 | /* Decrypt the token. It should read TEST in Unicode. */
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240 | RC4_set_key(&crypt_key, 16, g_licence_key);
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241 | RC4(&crypt_key, LICENCE_TOKEN_SIZE, in_token, decrypt_token);
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242 |
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243 | /* Generate a signature for a buffer of token and HWID */
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244 | licence_generate_hwid(hwid);
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245 | memcpy(sealed_buffer, decrypt_token, LICENCE_TOKEN_SIZE);
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246 | memcpy(sealed_buffer + LICENCE_TOKEN_SIZE, hwid, LICENCE_HWID_SIZE);
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247 | sec_sign(out_sig, 16, g_licence_sign_key, 16, sealed_buffer, sizeof(sealed_buffer));
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248 |
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249 | /* Now encrypt the HWID */
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250 | RC4_set_key(&crypt_key, 16, g_licence_key);
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251 | RC4(&crypt_key, LICENCE_HWID_SIZE, hwid, crypt_hwid);
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252 |
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253 | licence_send_authresp(out_token, crypt_hwid, out_sig);
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254 | }
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255 |
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256 | /* Process an licence issue packet */
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257 | static void
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258 | licence_process_issue(STREAM s)
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259 | {
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260 | RC4_KEY crypt_key;
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261 | uint32 length;
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262 | uint16 check;
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263 | int i;
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264 |
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265 | in_uint8s(s, 2); /* 3d 45 - unknown */
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266 | in_uint16_le(s, length);
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267 | if (!s_check_rem(s, length))
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268 | return;
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269 |
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270 | RC4_set_key(&crypt_key, 16, g_licence_key);
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271 | RC4(&crypt_key, length, s->p, s->p);
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272 |
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273 | in_uint16(s, check);
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274 | if (check != 0)
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275 | return;
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276 |
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277 | g_licence_issued = True;
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278 |
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279 | in_uint8s(s, 2); /* pad */
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280 |
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281 | /* advance to fourth string */
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282 | length = 0;
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283 | for (i = 0; i < 4; i++)
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284 | {
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285 | in_uint8s(s, length);
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286 | in_uint32_le(s, length);
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287 | if (!s_check_rem(s, length))
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288 | return;
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289 | }
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290 |
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291 | g_licence_issued = True;
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292 | save_licence(s->p, length);
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293 | }
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294 |
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295 | /* Process a licence packet */
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296 | void
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297 | licence_process(STREAM s)
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298 | {
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299 | uint8 tag;
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300 |
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301 | in_uint8(s, tag);
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302 | in_uint8s(s, 3); /* version, length */
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303 |
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304 | switch (tag)
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305 | {
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306 | case LICENCE_TAG_DEMAND:
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307 | licence_process_demand(s);
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308 | break;
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309 |
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310 | case LICENCE_TAG_AUTHREQ:
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311 | licence_process_authreq(s);
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312 | break;
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313 |
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314 | case LICENCE_TAG_ISSUE:
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315 | licence_process_issue(s);
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316 | break;
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317 |
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318 | case LICENCE_TAG_REISSUE:
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319 | case LICENCE_TAG_RESULT:
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320 | break;
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321 |
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322 | default:
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323 | unimpl("licence tag 0x%x\n", tag);
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324 | }
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325 | }
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