Repository navigation
Expand file tree
/
Copy pathcrypt.c
More file actions
216 lines (186 loc) · 6.18 KB
/
Copy pathcrypt.c
File metadata and controls
216 lines (186 loc) · 6.18 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
#ifndef __GNUC__
#pragma code_seg( "RTV_TEXT" )
#pragma data_seg( "RTV_DATA" )
#pragma bss_seg( "RTV_BSS" )
#pragma const_seg( "RTV_RD" )
#endif
/*
* Copyright (C) 2002 John Todd Larason <jtl@molehill.org>
*
* 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.
*/
#include "crypt.h"
#include "md5.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
static void checksum(unsigned char * dest, unsigned const char * src, u32 len,
int checksum_num)
{
static unsigned char extradata[][64] = {{
0x41,0x47,0xc8,0x09, 0xba,0x3c,0x99,0x6a,
0xda,0x09,0x9a,0x0f, 0xc0,0xd3,0x47,0xca,
0xd1,0x95,0x81,0x19, 0xab,0x17,0xc6,0x5f,
0xad,0xea,0xe5,0x75, 0x9c,0x49,0x18,0xa5,
0xdf,0x35,0x46,0x5b, 0x78,0x0e,0xcb,0xc7,
0x8c,0x3e,0xf4,0x90, 0xa2,0xb7,0x8e,0x00,
0x53,0x8d,0x4c,0xab, 0x13,0xa5,0x16,0x00,
0xff,0xb8,0x4b,0x20, 0x29,0x22,0x9d,0xee,
}, {
0xda,0x76,0x5c,0xd4, 0x34,0xc3,0xd7,0x2c,
0xac,0x40,0xb8,0xd8, 0x59,0xbc,0x59,0x34,
0xaa,0xbf,0x89,0xbd, 0x85,0xe8,0x40,0x27,
0x78,0x2b,0x18,0x6e, 0xa6,0x6e,0x5a,0xc6,
0xda,0xe3,0x86,0x84, 0x40,0x14,0x2a,0x23,
0x4f,0x5d,0x38,0x5e, 0x7f,0xd9,0x73,0x7d,
0xe4,0x80,0x3d,0x21, 0x28,0x41,0xf1,0xb2,
0x96,0x43,0x2b,0xcc, 0x0c,0x9d,0x26,0xb9,
}};
rtv_md5_context c;
rtv_md5_starts(&c);
rtv_md5_update(&c, src, len);
rtv_md5_update(&c, extradata[checksum_num], sizeof extradata[checksum_num]);
rtv_md5_finish(&c, dest);
}
static u32 cryptblock(u32 k, char * buf, u32 size)
{
u32 i;
for (i = 0; i < size; i++) {
k = k * 0xb8f7 + 0x15bb9;
buf[i] ^= k;
}
return k;
}
/* cyphertext bytes:
*
* 2, 4, 1, 7 -- key material block 1
* 0, 3, 5, 6 -- unknown/unused
* 8..23 -- checksum(24..end)
* 24..27 -- crypt(0x42ffdfa9)
* 28..31 -- crypt(time_t)
* 32..end -- crypt(text)
*
* it looks like you should be able to decrypt 24..end in one step, after
* getting the key material, if you don't want to do the sanity check first
* and don't mind it all in one buffer
*/
int rtv_decrypt(const char * cyphertext, u32 cyphertext_len,
char * plainbuf, u32 plainbuf_len,
u32 * p_time, u32 * p_plain_len,
int checksum_num)
{
unsigned char key_buf[4];
unsigned char sanity_buf[4];
unsigned char time_buf[4];
unsigned char csum_buf[16];
unsigned char * p;
u32 key;
u32 sanity;
#if VERBOSE_OBFUSC
unsigned char obfusc_buf[4];
u32 obfusc;
#endif
if (plainbuf_len < cyphertext_len - 32)
return -1;
/* unshuffle the key and unxor it */
key_buf[0] = cyphertext[2];
key_buf[1] = cyphertext[4];
key_buf[2] = cyphertext[1];
key_buf[3] = cyphertext[7];
p = key_buf;
key = rtv_to_u32(&p) ^ 0xcb0baf47;
#if VERBOSE_OBFUSC
obfusc_buf[0] = cyphertext[0];
obfusc_buf[1] = cyphertext[3];
obfusc_buf[2] = cyphertext[5];
obfusc_buf[3] = cyphertext[6];
p = key_buf;
obfusc = rtv_to_u32(&p);
//fprintf(stderr, "Key: %ld (0x%lx)\n", (unsigned long)key, (unsigned long)key);
//fprintf(stderr, "Obfusc: %ld (0x%lx)\n", (unsigned long)obfusc, (unsigned long)obfusc);
#endif
/* check the sanity field */
memcpy(sanity_buf, cyphertext + 24, 4);
key = cryptblock(key, (char*)sanity_buf, 4);
p = sanity_buf;
sanity = rtv_to_u32(&p);
if (sanity != 0x42ffdfa9)
return -1;
/* decrypt the time field */
memcpy(time_buf, cyphertext + 28, 4);
key = cryptblock(key, (char*)time_buf, 4);
/* decrypt the actual text */
memcpy(plainbuf, cyphertext + 32, cyphertext_len - 32);
cryptblock(key, (char*)plainbuf, cyphertext_len - 32);
/* check the checksum */
checksum(csum_buf, (unsigned const char*)(cyphertext + 24), cyphertext_len - 24, checksum_num);
if (memcmp(csum_buf, cyphertext + 8, 16) != 0)
return -2;
if (p_plain_len) {
*p_plain_len = cyphertext_len - 32;
}
if (p_time) {
p = time_buf;
*p_time = rtv_to_u32(&p);
#if VERBOSE_OBFUSC
// fprintf(stderr, "Time: %ld (0x%lx)\n", (unsigned long)*p_time, (unsigned long)*p_time);
#endif
}
return 0;
}
int rtv_encrypt(const char * plaintext, u32 plaintext_len,
char * cyphertext, u32 buffer_len, u32 * cyphertext_len,
int checksum_num)
{
u32 key;
u32 t;
u32 obfusc;
unsigned char key_buf[4];
unsigned char obfusc_buf[4];
unsigned char * p;
if (buffer_len < plaintext_len + 32)
return -1;
/* make up a key and obfuscatory material; get the time */
key = rand();
obfusc = rand();
t = (u32)time(NULL);
p = NULL;//getenv("TIMEOFF");
if (p)
t += atoi((char*)p);
/* encrypt the key */
p = key_buf;
rtv_from_u32(&p, key ^ 0xcb0baf47);
p = obfusc_buf;
rtv_from_u32(&p, obfusc);
/* scramble the key and obfusc material */
cyphertext[0] = obfusc_buf[3];
cyphertext[1] = key_buf[2];
cyphertext[2] = key_buf[0];
cyphertext[3] = obfusc_buf[2];
cyphertext[4] = key_buf[1];
cyphertext[5] = obfusc_buf[1];
cyphertext[6] = obfusc_buf[0];
cyphertext[7] = key_buf[3];
/* store the sanity check & time */
p = (unsigned char*)(cyphertext + 24);
rtv_from_u32(&p, 0x42ffdfa9);
rtv_from_u32(&p, t);
/* copy the plaintext */
memcpy(p, plaintext, plaintext_len);
/* encrypt the whole thing */
cryptblock(key, cyphertext+24, plaintext_len+8);
/* fill in the checksum */
checksum((unsigned char*)(cyphertext + 8), (unsigned const char*)(cyphertext + 24), plaintext_len + 8, checksum_num);
/* and we're done */
*cyphertext_len = plaintext_len + 32;
return 0;
}