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
|
/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#ifndef ARCHETYPE_CRYPT
#define ARCHETYPE_CRYPT
#include "glk/archetype/string.h"
namespace Glk {
namespace Archetype {
enum EncryptionType {
NONE, SIMPLE, PURPLE, UNPURPLE, COMPLEX, DEBUGGING_ON
};
extern byte CryptMask;
extern EncryptionType Encryption;
/**
* Initializes fields local to the file
*/
extern void crypt_init();
extern void cryptinit(EncryptionType crypt_kind, uint seed);
/**
* Encrypts or decrypts a string.Since all encryption methods are based on XOR,
* the same method both encrypts anddecrypts.
* If <method> is SIMPLE, the CryptMask is simply XORed with each byte in the string.
* If <method> is PURPLE, the CryptMask is changed each time after using it,
* by adding to it the lowest three bits of the result of the last encrypted
* byte.This way the mask changes frequently anddynamically in a way that
* is difficult to predict.
* If <method> is UNPURPLE, the same algorithm as PURPLE is used except that
* the next CryptMask must be determined before altering the byte under consideration.
* if <method> is COMPLEX, a pseudorandom sequence is used to alter the
* CryptMask.This can make prediction well-nigh impossible.
*/
extern void cryptstr(char *buffer, size_t length);
} // End of namespace Archetype
} // End of namespace Glk
#endif
|
