
/*
  * Copyright 2004,2005 The Apache Software Foundation.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
*/

/* crypt.h -- base code for crypt/uncrypt ZIPfile

   Version 1.01e, February 12th, 2005

   Copyright (C) 1998-2005 Gilles Vollant

   This code is a modified version of crypting code in Infozip distribution

   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.

   This code support the "Traditional PKWARE Encryption".

   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.
*/

#define CRC32(c, b) ((*(pcrc_32_tab+(((int)(c) ^ (b)) & 0xff))) ^ ((c) >> 8))

/***********************************************************************
 * Return the next byte in the pseudo-random sequence
 */
int decrypt_byte(
    unsigned long *pkeys,
    const unsigned long *pcrc_32_tab);

/***********************************************************************
 * Update the encryption keys with the next byte of plain text
 */
int update_keys(
    unsigned long *pkeys,
    const unsigned long *pcrc_32_tab,
    int c);

/***********************************************************************
 * Initialize the encryption keys and the random header according to
 * the given password.
 */
void init_keys(
    const char *passwd,
    unsigned long *pkeys,
    const unsigned long *pcrc_32_tab);

#define zdecode(pkeys,pcrc_32_tab,c) \
    (update_keys(pkeys,pcrc_32_tab,c ^= decrypt_byte(pkeys,pcrc_32_tab)))

#define zencode(pkeys,pcrc_32_tab,c,t) \
    (t=decrypt_byte(pkeys,pcrc_32_tab), 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

int crypthead(
    passwd,
    buf,
    bufSize,
    pkeys,
    pcrc_32_tab,
    crcForCrypting);

#endif