Subversion Repositories autosfx

#include "stdafx.h"

#pragma hdrstop        

#include "common.h"

#include "crypt.h"

#include "dz_errs.h"

#undef _DZ_FILE_

#define _DZ_FILE_ DZ_CRYPT_CPP

//#include "ZipErr.h"

/* crypt.c (full version) by Info-ZIP.      Last revised:  [see crypt.h]

 *

 * This code is not copyrighted and is put in the public domain.  The

 * encryption/decryption parts (as opposed to the non-echoing password

 * parts) were originally written in Europe; the whole file can there-

 * fore be freely distributed from any country except the USA.  If this

 * code is imported into the USA, it cannot be re-exported from from

 * there to another country.  (This restriction might seem curious, but

 * this is what US law requires.)

 */

/* 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).

 * This version modified by Chris Vleghert and Eric Engler for BCB/Delphi Zip.

  ** distributed under LGPL license ** see license.txt for details

 */

/* For the encoding task used in Zip (and ZipCloak), we want to initialize

 * the crypt algorithm with some reasonably unpredictable bytes, see

 * the crypthead() function. The standard rand() library function is

 * used to supply these 'random' bytes, which in turn is initialized by

 * a srand() call. The srand() function takes an "unsigned" (at least 16bit)

 * seed value as argument to determine the starting point of the rand()

 * pseudo-random number generator.

 * This seed number is constructed as "Seed = Seed1 .XOR. Seed2" with

 * Seed1 supplied by the current time (= "(unsigned)time()") and Seed2

 * as some (hopefully) nondeterministic bitmask. On many (most) systems,

 * we use some "process specific" number, as the PID or something similar,

 * but when nothing unpredictable is available, a fixed number may be

 * sufficient.

 * NOTE:

 * 1.) This implementation requires the availability of the following

 *     standard UNIX C runtime library functions: time(), rand(), srand().

 *     On systems where some of them are missing, the environment that

 *     incorporates the crypt routines must supply suitable replacement

 *     functions.

 * 2.) It is a very bad idea to use a second call to time() to set the

 *     "Seed2" number! In this case, both "Seed1" and "Seed2" would be

 *     (almost) identical, resulting in a (mostly) "zero" constant seed

 *     number passed to srand().

 *

 * The implementation environment defined in the "zip.h" header should

 * supply a reasonable definition for ZCR_SEED2 (an unsigned number; for

 * most implementations of rand() and srand(), only the lower 16 bits are

 * significant!). An example that works on many systems would be

 *      "#define ZCR_SEED2  (unsigned)getpid()".

 * The default definition for ZCR_SEED2 supplied below should be regarded

 * as a fallback to allow successful compilation in "beta state"

 * environments.

 *

  Copyright (c) 1990-2007 Info-ZIP.  All rights reserved.

  See the accompanying file LICENSE, version 2007-Mar-4 or later

  (the contents of which are also included in zip.h) for terms of use.

  If, for some reason, all these files are missing, the Info-ZIP license

  also may be found at:  ftp://ftp.info-zip.org/pub/infozip/license.html

  parts Copyright (C) 1997 Mike White, Eric W. Engler

************************************************************************

 Copyright (C) 2009, 2010  by Russell J. Peters, Roger Aelbrecht

   This file is part of TZipMaster Version 1.9.

    TZipMaster is free software: you can redistribute it and/or modify

    it under the terms of the GNU Lesser General Public License as published by

    the Free Software Foundation, either version 3 of the License, or

    (at your option) any later version.

    TZipMaster 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License

    along with TZipMaster.  If not, see <http://www.gnu.org/licenses/>.

    contact: problems@delphizip.org (include ZipMaster in the subject).

    updates: http://www.delphizip.org

    DelphiZip maillist subscribe at http://www.freelists.org/list/delphizip

************************************************************************/

// "last resort" source for second part of crypt seed pattern

#ifndef ZCR_SEED2 // RCV: Is now defined in Zip.h

#define ZCR_SEED2 (unsigned)3141592654L // use PI as default pattern

#endif

#define CRC32(c, b) (crc_table[((int)(c) ^ (b)) & 0xFF] ^ ((c) >> 8))

// Return the next byte in the pseudo-random sequence

int _fastcall decrypt_byte(Keys keys)

{

    unsigned  temp;

    temp = ((unsigned)keys[2] & 0xFFFF) | 2;

    return (int)(((temp *(temp ^ 1)) >> 8) & 0xFF);

}

// Update the encryption keys with the next byte of plain text c :: Byte of

//   plain text.

int  _fastcall update_keys(int c, Keys keys)

{

    keys[0] = CRC32(keys[0], c);

    keys[1] += keys[0] & 0xFF;

    keys[1] = keys[1] * 134775813L + 1;

    {

        register int  keyshift = (int)(keys[1] >> 24);

        keys[2] = CRC32(keys[2], keyshift);

    }

    return c;

}

// Initialize the encryption keys and the random header according to the

//   given password. passwd :: Password string with which to modify keys.

void _fastcall init_keys(const char *passwd, Keys keys)

{

    keys[0] = 305419896L;

    keys[1] = 591751049L;

    keys[2] = 878082192L;

    while (*passwd != '\0')

    {

        update_keys((int) *passwd, keys);

        passwd++;

    }

}

int _fastcall zencode(int c, Keys keys)

{

    int t;

    unsigned  temp;

    temp = ((unsigned)keys[2] & 0xFFFF) | 2;

    t = (int)(((temp * (temp ^ 1)) >> 8) & 0xFF);

    keys[0] = CRC32(keys[0], c);

    keys[1] += keys[0] & 0xFF;

    keys[1] = keys[1] * 134775813L + 1;

    {

        register int  keyshift = (int)(keys[1] >> 24);

        keys[2] = CRC32(keys[2], keyshift);

    }

    return t ^ c;

}

int _fastcall zdecode(int c, Keys keys)

{

    int t;

    unsigned  temp;

    temp = ((unsigned)keys[2] & 0xFFFF) | 2;

    t = (int)(((temp * (temp ^ 1)) >> 8) & 0xFF);

    t ^= c;

    keys[0] = CRC32(keys[0], t);

    keys[1] += keys[0] & 0xFF;

        keys[1] = keys[1] * 134775813L + 1;

    {

        register int  keyshift = (int)(keys[1] >> 24);

        keys[2] = CRC32(keys[2], keyshift);

    }

    return t;

}