Repository navigation
Expand file tree
/
Copy pathcrypt_zip.c
More file actions
158 lines (138 loc) · 3.38 KB
/
Copy pathcrypt_zip.c
File metadata and controls
158 lines (138 loc) · 3.38 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
/* vi:set ts=8 sts=4 sw=4 noet:
*
* VIM - Vi IMproved by Bram Moolenaar
*
* Do ":help uganda" in Vim to read copying and usage conditions.
* Do ":help credits" in Vim to see a list of people who contributed.
* See README.txt for an overview of the Vim source code.
*/
/*
* crypt_zip.c: Zip encryption support.
*/
#include "vim.h"
#if defined(FEAT_CRYPT) || defined(PROTO)
/*
* Optional encryption support.
* Mohsin Ahmed, mosh@sasi.com, 98-09-24
* Based on zip/crypt sources.
*
* NOTE FOR USA: Since 2000 exporting this code from the USA is allowed to
* most countries. There are a few exceptions, but that still should not be a
* problem since this code was originally created in Europe and India.
*/
/* Need a type that should be 32 bits. 64 also works but wastes space. */
# if VIM_SIZEOF_INT >= 4
typedef unsigned int u32_T; /* int is at least 32 bits */
# else
typedef unsigned long u32_T; /* long should be 32 bits or more */
# endif
/* The state of encryption, referenced by cryptstate_T. */
typedef struct {
u32_T keys[3];
} zip_state_T;
static void make_crc_tab(void);
static u32_T crc_32_table[256];
/*
* Fill the CRC table, if not done already.
*/
static void
make_crc_tab(void)
{
u32_T s, t, v;
static int done = FALSE;
if (done)
return;
for (t = 0; t < 256; t++)
{
v = t;
for (s = 0; s < 8; s++)
v = (v >> 1) ^ ((v & 1) * (u32_T)0xedb88320L);
crc_32_table[t] = v;
}
done = TRUE;
}
#define CRC32(c, b) (crc_32_table[((int)(c) ^ (b)) & 0xff] ^ ((c) >> 8))
/*
* Return the next byte in the pseudo-random sequence.
*/
#define DECRYPT_BYTE_ZIP(keys, t) { \
short_u temp = (short_u)keys[2] | 2; \
t = (int)(((unsigned)(temp * (temp ^ 1U)) >> 8) & 0xff); \
}
/*
* Update the encryption keys with the next byte of plain text.
*/
#define UPDATE_KEYS_ZIP(keys, c) { \
keys[0] = CRC32(keys[0], (c)); \
keys[1] += keys[0] & 0xff; \
keys[1] = keys[1] * 134775813L + 1; \
keys[2] = CRC32(keys[2], (int)(keys[1] >> 24)); \
}
/*
* Initialize for encryption/decryption.
*/
void
crypt_zip_init(
cryptstate_T *state,
char_u *key,
char_u *salt UNUSED,
int salt_len UNUSED,
char_u *seed UNUSED,
int seed_len UNUSED)
{
char_u *p;
zip_state_T *zs;
zs = (zip_state_T *)alloc(sizeof(zip_state_T));
state->method_state = zs;
make_crc_tab();
zs->keys[0] = 305419896L;
zs->keys[1] = 591751049L;
zs->keys[2] = 878082192L;
for (p = key; *p != NUL; ++p)
{
UPDATE_KEYS_ZIP(zs->keys, (int)*p);
}
}
/*
* Encrypt "from[len]" into "to[len]".
* "from" and "to" can be equal to encrypt in place.
*/
void
crypt_zip_encode(
cryptstate_T *state,
char_u *from,
size_t len,
char_u *to)
{
zip_state_T *zs = state->method_state;
size_t i;
int ztemp, t;
for (i = 0; i < len; ++i)
{
ztemp = from[i];
DECRYPT_BYTE_ZIP(zs->keys, t);
UPDATE_KEYS_ZIP(zs->keys, ztemp);
to[i] = t ^ ztemp;
}
}
/*
* Decrypt "from[len]" into "to[len]".
*/
void
crypt_zip_decode(
cryptstate_T *state,
char_u *from,
size_t len,
char_u *to)
{
zip_state_T *zs = state->method_state;
size_t i;
short_u temp;
for (i = 0; i < len; ++i)
{
temp = (short_u)zs->keys[2] | 2;
temp = (int)(((unsigned)(temp * (temp ^ 1U)) >> 8) & 0xff);
UPDATE_KEYS_ZIP(zs->keys, to[i] = from[i] ^ temp);
}
}
#endif /* FEAT_CRYPT */