0,0 → 1,132 |
/* crypt.h -- base code for crypt/uncrypt ZIPfile |
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Version 1.01e, February 12th, 2005 |
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Copyright (C) 1998-2005 Gilles Vollant |
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This code is a modified version of crypting code in Infozip distribution |
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The encryption/decryption parts of this source code (as opposed to the |
non-echoing password parts) were originally written in Europe. The |
whole source package can be freely distributed, including from the USA. |
(Prior to January 2000, re-export from the US was a violation of US law.) |
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This encryption code is a direct transcription of the algorithm from |
Roger Schlafly, described by Phil Katz in the file appnote.txt. This |
file (appnote.txt) is distributed with the PKZIP program (even in the |
version without encryption capabilities). |
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If you don't need crypting in your application, just define symbols |
NOCRYPT and NOUNCRYPT. |
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This code support the "Traditional PKWARE Encryption". |
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The new AES encryption added on Zip format by Winzip (see the page |
http://www.winzip.com/aes_info.htm ) and PKWare PKZip 5.x Strong |
Encryption is not supported. |
*/ |
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#define CRC32(c, b) ((*(pcrc_32_tab+(((int)(c) ^ (b)) & 0xff))) ^ ((c) >> 8)) |
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/*********************************************************************** |
* Return the next byte in the pseudo-random sequence |
*/ |
static int decrypt_byte(unsigned long* pkeys, const unsigned long* pcrc_32_tab) |
{ |
unsigned temp; /* POTENTIAL BUG: temp*(temp^1) may overflow in an |
* unpredictable manner on 16-bit systems; not a problem |
* with any known compiler so far, though */ |
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temp = ((unsigned)(*(pkeys+2)) & 0xffff) | 2; |
return (int)(((temp * (temp ^ 1)) >> 8) & 0xff); |
} |
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/*********************************************************************** |
* Update the encryption keys with the next byte of plain text |
*/ |
static int update_keys(unsigned long* pkeys,const unsigned long* pcrc_32_tab,int c) |
{ |
(*(pkeys+0)) = CRC32((*(pkeys+0)), c); |
(*(pkeys+1)) += (*(pkeys+0)) & 0xff; |
(*(pkeys+1)) = (*(pkeys+1)) * 134775813L + 1; |
{ |
register int keyshift = (int)((*(pkeys+1)) >> 24); |
(*(pkeys+2)) = CRC32((*(pkeys+2)), keyshift); |
} |
return c; |
} |
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/*********************************************************************** |
* Initialize the encryption keys and the random header according to |
* the given password. |
*/ |
static void init_keys(const char* passwd,unsigned long* pkeys,const unsigned long* pcrc_32_tab) |
{ |
*(pkeys+0) = 305419896L; |
*(pkeys+1) = 591751049L; |
*(pkeys+2) = 878082192L; |
while (*passwd != '\0') { |
update_keys(pkeys,pcrc_32_tab,(int)*passwd); |
passwd++; |
} |
} |
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#define zdecode(pkeys,pcrc_32_tab,c) \ |
(update_keys(pkeys,pcrc_32_tab,c ^= decrypt_byte(pkeys,pcrc_32_tab))) |
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#define zencode(pkeys,pcrc_32_tab,c,t) \ |
(t=decrypt_byte(pkeys,pcrc_32_tab), update_keys(pkeys,pcrc_32_tab,c), t^(c)) |
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#ifdef INCLUDECRYPTINGCODE_IFCRYPTALLOWED |
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#define RAND_HEAD_LEN 12 |
/* "last resort" source for second part of crypt seed pattern */ |
# ifndef ZCR_SEED2 |
# define ZCR_SEED2 3141592654UL /* use PI as default pattern */ |
# endif |
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static int crypthead(passwd, buf, bufSize, pkeys, pcrc_32_tab, crcForCrypting) |
const char *passwd; /* password string */ |
unsigned char *buf; /* where to write header */ |
int bufSize; |
unsigned long* pkeys; |
const unsigned long* pcrc_32_tab; |
unsigned long crcForCrypting; |
{ |
int n; /* index in random header */ |
int t; /* temporary */ |
int c; /* random byte */ |
unsigned char header[RAND_HEAD_LEN-2]; /* random header */ |
static unsigned calls = 0; /* ensure different random header each time */ |
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if (bufSize<RAND_HEAD_LEN) |
return 0; |
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/* First generate RAND_HEAD_LEN-2 random bytes. We encrypt the |
* output of rand() to get less predictability, since rand() is |
* often poorly implemented. |
*/ |
if (++calls == 1) |
{ |
srand((unsigned)(time(NULL) ^ ZCR_SEED2)); |
} |
init_keys(passwd, pkeys, pcrc_32_tab); |
for (n = 0; n < RAND_HEAD_LEN-2; n++) |
{ |
c = (rand() >> 7) & 0xff; |
header[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, c, t); |
} |
/* Encrypt random header (last two bytes is high word of crc) */ |
init_keys(passwd, pkeys, pcrc_32_tab); |
for (n = 0; n < RAND_HEAD_LEN-2; n++) |
{ |
buf[n] = (unsigned char)zencode(pkeys, pcrc_32_tab, header[n], t); |
} |
buf[n++] = zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 16) & 0xff, t); |
buf[n++] = zencode(pkeys, pcrc_32_tab, (int)(crcForCrypting >> 24) & 0xff, t); |
return n; |
} |
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#endif |
Property changes: |
Added: svn:executable |
+* |
\ No newline at end of property |