ReactOS  0.4.13-dev-100-gc8611ae
crypt.h
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1 /* crypt.h -- base code for crypt/uncrypt ZIPfile
2 
3 
4  Version 1.01e, February 12th, 2005
5 
6  Copyright (C) 1998-2005 Gilles Vollant
7 
8  This code is a modified version of crypting code in Infozip distribution
9 
10  The encryption/decryption parts of this source code (as opposed to the
11  non-echoing password parts) were originally written in Europe. The
12  whole source package can be freely distributed, including from the USA.
13  (Prior to January 2000, re-export from the US was a violation of US law.)
14 
15  This encryption code is a direct transcription of the algorithm from
16  Roger Schlafly, described by Phil Katz in the file appnote.txt. This
17  file (appnote.txt) is distributed with the PKZIP program (even in the
18  version without encryption capabilities).
19 
20  If you don't need crypting in your application, just define symbols
21  NOCRYPT and NOUNCRYPT.
22 
23  This code support the "Traditional PKWARE Encryption".
24 
25  The new AES encryption added on Zip format by Winzip (see the page
26  http://www.winzip.com/aes_info.htm ) and PKWare PKZip 5.x Strong
27  Encryption is not supported.
28 */
29 
30 #define CRC32(c, b) ((*(pcrc_32_tab+(((int)(c) ^ (b)) & 0xff))) ^ ((c) >> 8))
31 
32 /***********************************************************************
33  * Return the next byte in the pseudo-random sequence
34  */
35 static int decrypt_byte(unsigned long* pkeys, const z_crc_t* pcrc_32_tab)
36 {
37  unsigned temp; /* POTENTIAL BUG: temp*(temp^1) may overflow in an
38  * unpredictable manner on 16-bit systems; not a problem
39  * with any known compiler so far, though */
40 
41  temp = ((unsigned)(*(pkeys+2)) & 0xffff) | 2;
42  return (int)(((temp * (temp ^ 1)) >> 8) & 0xff);
43 }
44 
45 /***********************************************************************
46  * Update the encryption keys with the next byte of plain text
47  */
48 static int update_keys(unsigned long* pkeys,const z_crc_t* pcrc_32_tab,int c)
49 {
50  (*(pkeys+0)) = CRC32((*(pkeys+0)), c);
51  (*(pkeys+1)) += (*(pkeys+0)) & 0xff;
52  (*(pkeys+1)) = (*(pkeys+1)) * 134775813L + 1;
53  {
54  register int keyshift = (int)((*(pkeys+1)) >> 24);
55  (*(pkeys+2)) = CRC32((*(pkeys+2)), keyshift);
56  }
57  return c;
58 }
59 
60 
61 /***********************************************************************
62  * Initialize the encryption keys and the random header according to
63  * the given password.
64  */
65 static void init_keys(const char* passwd,unsigned long* pkeys,const z_crc_t* pcrc_32_tab)
66 {
67  *(pkeys+0) = 305419896L;
68  *(pkeys+1) = 591751049L;
69  *(pkeys+2) = 878082192L;
70  while (*passwd != '\0') {
71  update_keys(pkeys,pcrc_32_tab,(int)*passwd);
72  passwd++;
73  }
74 }
75 
76 #define zdecode(pkeys,pcrc_32_tab,c) \
77  (update_keys(pkeys,pcrc_32_tab,c ^= decrypt_byte(pkeys,pcrc_32_tab)))
78 
79 #define zencode(pkeys,pcrc_32_tab,c,t) \
80  (t=decrypt_byte(pkeys,pcrc_32_tab), update_keys(pkeys,pcrc_32_tab,c), t^(c))
81 
82 #ifdef INCLUDECRYPTINGCODE_IFCRYPTALLOWED
83 
84 #define RAND_HEAD_LEN 12
85  /* "last resort" source for second part of crypt seed pattern */
86 # ifndef ZCR_SEED2
87 # define ZCR_SEED2 3141592654UL /* use PI as default pattern */
88 # endif
89 
90 static int crypthead(const char* passwd, /* password string */
91  unsigned char* buf, /* where to write header */
92  int bufSize,
93  unsigned long* pkeys,
94  const z_crc_t* pcrc_32_tab,
95  unsigned long crcForCrypting)
96 {
97  int n; /* index in random header */
98  int t; /* temporary */
99  int c; /* random byte */
100  unsigned char header[RAND_HEAD_LEN-2]; /* random header */
101  static unsigned calls = 0; /* ensure different random header each time */
102 
103  if (bufSize<RAND_HEAD_LEN)
104  return 0;
105 
106  /* First generate RAND_HEAD_LEN-2 random bytes. We encrypt the
107  * output of rand() to get less predictability, since rand() is
108  * often poorly implemented.
109  */
110  if (++calls == 1)
111  {
112  srand((unsigned)(time(NULL) ^ ZCR_SEED2));
113  }
114  init_keys(passwd, pkeys, pcrc_32_tab);
115  for (n = 0; n < RAND_HEAD_LEN-2; n++)
116  {
117  c = (rand() >> 7) & 0xff;
118  header[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, c, t);
119  }
120  /* Encrypt random header (last two bytes is high word of crc) */
121  init_keys(passwd, pkeys, pcrc_32_tab);
122  for (n = 0; n < RAND_HEAD_LEN-2; n++)
123  {
124  buf[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, header[n], t);
125  }
126  buf[n++] = (unsigned char)zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 16) & 0xff, t);
127  buf[n++] = (unsigned char)zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 24) & 0xff, t);
128  return n;
129 }
130 
131 #endif
unsigned long z_crc_t
Definition: zconf.h:431
GLenum GLuint GLenum GLsizei const GLchar * buf
Definition: glext.h:7751
#define zencode(pkeys, pcrc_32_tab, c, t)
Definition: crypt.h:79
void __cdecl srand(_In_ unsigned int _Seed)
GLdouble n
Definition: glext.h:7729
GLdouble GLdouble t
Definition: gl.h:2047
__u16 time
Definition: mkdosfs.c:366
static void init_keys(const char *passwd, unsigned long *pkeys, const z_crc_t *pcrc_32_tab)
Definition: crypt.h:65
GLuint GLsizei bufSize
Definition: glext.h:6040
_Check_return_ int __cdecl rand(void)
Definition: rand.c:10
smooth NULL
Definition: ftsmooth.c:416
unsigned char
Definition: typeof.h:29
static int update_keys(unsigned long *pkeys, const z_crc_t *pcrc_32_tab, int c)
Definition: crypt.h:48
const GLubyte * c
Definition: glext.h:8905
static const WCHAR L[]
Definition: oid.c:1250
static int decrypt_byte(unsigned long *pkeys, const z_crc_t *pcrc_32_tab)
Definition: crypt.h:35
static calc_node_t temp
Definition: rpn_ieee.c:38
#define c
Definition: ke_i.h:80
#define CRC32(c, b)
Definition: crypt.h:30
struct CFHEADER header
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unsigned int(__cdecl typeof(jpeg_read_scanlines))(struct jpeg_decompress_struct *
Definition: typeof.h:31