/*

* Copyright (c) 2002-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

* ** IMPORTANT ** PublishedPartner API's in this file are published to 3rd party developers via the 

* Symbian website. Changes to these API's should be treated as PublishedAll API changes and the Security TA should be consulted.

*

*/

/**

 @file 

 @publishedPartner

 @released 

*/

#ifndef __MODE_H__

#define __MODE_H__

#include <blocktransformation.h>

/**

* Abstract class defining the use of block transformation objects as block

* chaining modes.

*

* It is initialised with a subclass of CBlockTransformation,

* which it subsequently owns.  Calls to its Transform() function will call the

* Transform() function in the underlying CBlockTransformation object, and perform

* the additional transformation for block chaining in that mode.  This all means

* that if you want to do, say, AES encryption in CBC mode, you need to construct

* a CAESEncryptor object, then pass it to the CModeCBCEncryptor subclass of

* CBlockChainingMode, and subsequently use the CModeCBCEncryptor object to call

* Transform().

* 

* @publishedPartner

* @released 

*/

class CBlockChainingMode : public CBlockTransformation

{

public:

	virtual void Reset();

	virtual TInt BlockSize() const;

	virtual TInt KeySize() const;

public:

	/**

	* Sets the initialization vector.

	* 

	* @param aIV	The initialization vector.  The length of this descriptor must be

	*				the same as the underlying cipher's block size.

	*/

	virtual void SetIV(const TDesC8& aIV);

protected:

	/** Default constructor */

	IMPORT_C CBlockChainingMode();

	/** 

	 * Second phase constructor

	 * 

	 * This should be called last by derived classes' ContructL()s .

	 *

	 * @param aBT	A block transformation object

	 * @param aIV	Initialization vector, the length of this descriptor must be

	 *				the same as the underlying cipher's block size.

	 */

	IMPORT_C void ConstructL(CBlockTransformation* aBT, const TDesC8& aIV);

	/** The destructor frees all resources owned by the object, prior to its destruction. */

	IMPORT_C virtual ~CBlockChainingMode();

protected:

	/** A block transformation object */

	CBlockTransformation* iBT;

	/** 

	 * A buffer containing the feedback register

	 *

	 * This must equal the underlying cipher's block size in length. 

	 * Initially this register is filled with the initialization vector.

	 */

	HBufC8* iRegisterBuf;

	/** Encapsulates a pointer to iRegisterBuf */

	TPtr8 iRegister;

	/** 

	 * A buffer containing the Initialisation Vector (IV) 

	 *

	 * This must equal the underlying cipher's block size in length. 

	 */

	HBufC8* iIVBuf;

	/** Encapsulates a pointer to iIVBuf */

	TPtr8 iIV;

};

#endif	//	__MODE_H__