harbour-core/harbour/contrib/hbziparch/ZipCryptograph.h

////////////////////////////////////////////////////////////////////////////////
// This source file is part of the ZipArchive library source distribution and
// is Copyrighted 2000 - 2007 by Artpol Software - Tadeusz Dracz
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
// 
// For the licensing details refer to the License.txt file.
//
// Web Site: http://www.artpol-software.com
////////////////////////////////////////////////////////////////////////////////

/**
* \file ZipCryptograph.h
* Includes the CZipCryptograph class.
*
*/

#if !defined(ZIPARCHIVE_ZIPCRYPTOGRAPH_DOT_H)
#define ZIPARCHIVE_ZIPCRYPTOGRAPH_DOT_H

#if _MSC_VER > 1000
	#pragma once
	#pragma warning( push )
	#pragma warning (disable : 4100) // unreferenced formal parameter
#endif // _MSC_VER > 1000

#include "ZipAutoBuffer.h"
#include "ZipStorage.h"

class CZipFileHeader;

/**
	The base class for cryptographs used in encryption and decryption of file data.

	\see
		<a href="kb">0610201627</a>
*/
class ZIP_API CZipCryptograph
{
public:
	
	/**
		The encryption method.

		\see
			<a href="kb">0610201627</a>
	*/
	enum EncryptionMethod
	{
		encStandard,		///< The traditional zip encryption.
		encWinZipAes128,	///< WinZip AES 128-bit encryption.
		encWinZipAes192,	///< WinZip AES 192-bit encryption.
		encWinZipAes256,	///< WinZip AES 256-bit encryption.
		encNone = 0xFF		///< Indicates no encryption.
	};

	/**
		A factory method that creates an appropriate cryptograph for the given method.

		\param iEncryptionMethod
			The encryption method to create a cryptograph for. Can be one of #EncryptionMethod values.

		\return
			The new cryptograph. The caller is responsible for destroying the object.
			If the method is not supported, creates CZipCrc32Cryptograph.
	*/
	static CZipCryptograph* CreateCryptograph(int iEncryptionMethod);

	/**
		Determines if the given method is one of the WinZip AES encryption method.

		\param iEncryptionMethod
			The encryption method to test. Can be one of #EncryptionMethod values.

		\return
			\c true, if the method is one the WinZip AES encryption methods; \c false otherwise.
	*/
	static bool IsWinZipAesEncryption(int iEncryptionMethod)
	{
		return iEncryptionMethod == encWinZipAes128 || iEncryptionMethod == encWinZipAes192 || iEncryptionMethod == encWinZipAes256;
	}

	/**
		Returns the total size of the extra data that is added to the compression stream during encryption with the given method.

		\param iEncryptionMethod
			The encryption method. Can be one of #EncryptionMethod values.

		\return
			The total size of extra data for the given encryption method.

	*/
	static DWORD GetEncryptedInfoSize(int iEncryptionMethod);

	/**
		Returns the size of the extra data that is added before the compression stream during encryption with the given method.

		\param iEncryptionMethod
			The encryption method. Can be one of #EncryptionMethod values.

		\return
			The size of extra data at the beginning of the compression stream for the given encryption method.

	*/
	static DWORD GetEncryptedInfoSizeBeforeData(int iEncryptionMethod);

	/**
		Returns the size of the extra data that is added after the compression stream during encryption with the given method.

		\param iEncryptionMethod
			The encryption method. Can be one of #EncryptionMethod values.

		\return
			The size of extra data at the end of the compression stream for the given encryption method.

	*/
	static DWORD GetEncryptedInfoSizeAfterData(int iEncryptionMethod);

	/**
		Determines if the given encryption method is supported by the current compilation of the ZipArchive Library.

		\param iEncryptionMethod
			The encryption method to test. Can be one of #EncryptionMethod values.

		\return
			\c true, if the method is supported; \c false otherwise.
	*/
	static bool IsEncryptionSupported(int iEncryptionMethod)
	{		
		return iEncryptionMethod == encStandard;
	}

	/**
		The method called when an existing file is opened for extraction.
	
		\param password
			The supplied password with the CZipArchive::SetPassword method.
	
		\param currentFile
			The file being decoded and extracted.
	
		\param storage
			The current CZipStorage.
	
		\return
			\c true, if the password is initially considered correct; \c false otherwise.	
	 */
	virtual bool InitDecode(CZipAutoBuffer& password, CZipFileHeader& currentFile, CZipStorage& storage) = 0;

	/**
		The method called when a new file is opened for compression.
		
		\param password
			The supplied password with the CZipArchive::SetPassword method.
		
		\param currentFile
			The file being compressed and encoded.
		
		\param storage
			The current CZipStorage.		
	 */
	virtual void InitEncode(CZipAutoBuffer& password, CZipFileHeader& currentFile, CZipStorage& storage) = 0;

	/**
		Decodes the given data.
	
		\param pBuffer
			The buffer that holds the data to decode and that receives the results.
	
		\param uSize
			The size of \a pBuffer.	
	 */
	virtual void Decode(char* pBuffer, DWORD uSize) = 0;

	/**
		Encodes the given data.
	
		\param pBuffer
			The buffer that holds the data to encode and that receives the results.
	
		\param uSize
			The size of \a pBuffer.	
	 */
	virtual void Encode(char* pBuffer, DWORD uSize) = 0;

	/**
		The method called at the end of the decoding process.
	
		\param currentFile
			The file being decoded and extracted.
	
		\param storage
			The current CZipStorage.
	 */
	virtual void FinishDecode(CZipFileHeader& currentFile, CZipStorage& storage){};

	/**
		The method called at the end of the decoding process.
	
		\param currentFile
			The file being compressed and encoded.
	
		\param storage
			The current CZipStorage.
	 */
	virtual void FinishEncode(CZipFileHeader& currentFile, CZipStorage& storage){};

	/**
		Returns the value indicating whether the current compressor can handle the given encryption method.

		\param iEncryptionMethod
			The encryption method to test. Can be one of #EncryptionMethod values.

		\return 
			\c true, if the current compressor can handle the given encryption method; \c false otherwise.
	*/
	virtual bool CanHandle(int iEncryptionMethod)
	{
		return false;
	}
	virtual ~CZipCryptograph(){}
};

#if _MSC_VER > 1000
	#pragma warning( pop )
#endif // _MSC_VER > 1000

#endif