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Copy pathcrypt.h
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137 lines (114 loc) · 4.9 KB
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/* crypt.h -- base code for traditional PKWARE encryption
Version 1.01e, February 12th, 2005
Copyright (C) 1998-2005 Gilles Vollant
Modifications for Info-ZIP crypting
Copyright (C) 2003 Terry Thorsen
This code is a modified version of crypting code in Info-ZIP distribution
Copyright (C) 1990-2000 Info-ZIP. All rights reserved.
See the Info-ZIP LICENSE file version 2000-Apr-09 or later for terms of use
which also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
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.)
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).
If you don't need crypting in your application, just define symbols
NOCRYPT and NOUNCRYPT.
Mar 8th, 2016 - Lucio Cosmo
Fixed support for 64bit builds for archives with "PKWARE" password.
Changed long, unsigned long, unsigned to unsigned int in
access functions to crctables and pkeys
*/
#define CRC32(c, b) ((*(pcrc_32_tab+(((uint32_t)(c) ^ (b)) & 0xff))) ^ ((c) >> 8))
/***********************************************************************
* Return the next byte in the pseudo-random sequence
*/
static uint8_t decrypt_byte(uint32_t *pkeys)
{
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 */
temp = ((uint32_t)(*(pkeys+2)) & 0xffff) | 2;
return (uint8_t)(((temp * (temp ^ 1)) >> 8) & 0xff);
}
/***********************************************************************
* Update the encryption keys with the next byte of plain text
*/
static uint8_t update_keys(uint32_t *pkeys, const uint32_t *pcrc_32_tab, uint8_t c)
{
(*(pkeys+0)) = CRC32((*(pkeys+0)), c);
(*(pkeys+1)) += (*(pkeys+0)) & 0xff;
(*(pkeys+1)) = (*(pkeys+1)) * 134775813L + 1;
{
register uint32_t keyshift = (uint32_t)((*(pkeys + 1)) >> 24);
(*(pkeys+2)) = CRC32((*(pkeys+2)), keyshift);
}
return c;
}
/***********************************************************************
* Initialize the encryption keys and the random header according to
* the given password.
*/
static void init_keys(const char *passwd, uint32_t *pkeys, const uint32_t *pcrc_32_tab)
{
*(pkeys+0) = 305419896L;
*(pkeys+1) = 591751049L;
*(pkeys+2) = 878082192L;
while (*passwd != 0)
{
update_keys(pkeys, pcrc_32_tab, (uint8_t)*passwd);
passwd += 1;
}
}
#define zdecode(pkeys,pcrc_32_tab,c) \
(update_keys(pkeys,pcrc_32_tab,c ^= decrypt_byte(pkeys)))
#define zencode(pkeys,pcrc_32_tab,c,t) \
(t=decrypt_byte(pkeys), update_keys(pkeys,pcrc_32_tab,c), t^(c))
#ifdef INCLUDECRYPTINGCODE_IFCRYPTALLOWED
#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
static int crypthead(const char *passwd, /* password string */
uint8_t *buf, /* where to write header */
int buf_size,
uint32_t *pkeys,
const uint32_t *pcrc_32_tab,
uint32_t crc_for_crypting)
{
uint8_t n = 0; /* index in random header */
uint8_t c = 0; /* random byte */
uint8_t header[RAND_HEAD_LEN-2]; /* random header */
uint16_t t = 0; /* temporary */
static unsigned calls = 0; /* ensure different random header each time */
if (buf_size < RAND_HEAD_LEN)
return 0;
/* 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] = (uint8_t)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] = (uint8_t)zencode(pkeys, pcrc_32_tab, header[n], t);
}
buf[n++] = (uint8_t)zencode(pkeys, pcrc_32_tab, (uint8_t)((crc_for_crypting >> 16) & 0xff), t);
buf[n++] = (uint8_t)zencode(pkeys, pcrc_32_tab, (uint8_t)((crc_for_crypting >> 24) & 0xff), t);
return n;
}
#endif