/*

* 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 __BUFFEREDTRANSFORMATION_H__

#define __BUFFEREDTRANSFORMATION_H__

#include <e32std.h>

#include "msymmetriccipher.h"

#include "blocktransformation.h"

class CPadding;

/**

 * Abstract class, deriving from CSymmetricCipher, encapsulating the buffering

 * logic for block ciphers.

 *

 * It is responsible for feeding complete blocks of plaintext or ciphertext to

 * the underlying encryptor or decryptor.  Since the only difference between

 * block cipher encryption and decryption is the ProcessFinalL() call,

 * CBufferedTransformation implements all functions (by buffering and/or

 * forwarding to the encryptor/decryptor) except ProcessFinalL() and

 * MaxFinalOutputLength().

 *

 * See the Cryptography api-guide documentation for the rules that this class

 * and derived classes must follow.

 *

 */

class CBufferedTransformation : public CSymmetricCipher

{

public:

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

	IMPORT_C virtual ~CBufferedTransformation();

public:

	/**

	 * Encrypts or decrypts the input using the underlying block cipher, buffering

	 * the input as necessary. 

	 *

	 * See the Cryptography api-guide documentation.

	 *

	 * @param aInput	The input is appended to the internal buffer (initially empty),

	 *					then all whole blocks are encrypted using the underlying block

	 *					transformation and written into aOutput. Any leftover bytes will

	 *					be buffered.

	 * @param aOutput	The resulting processed data appended to aOutput.  aOutput must

	 *					have at least MaxOutputLength() empty bytes remaining in its length.

	 */

	virtual void Process(const TDesC8& aInput, TDes8& aOutput);

	virtual TInt MaxOutputLength(TInt aInputLength) const;

	virtual void Reset();

	virtual TInt BlockSize() const;

	virtual TInt KeySize() const;

public:

	/** 

	 * Gets the underlying block transform.

	 *

	 * @return	A pointer to the CBlockTransformation object

	 */

	 IMPORT_C CBlockTransformation* BlockTransformer() const;

protected:

	/** @internalAll */

	CBufferedTransformation();

	/** @internalAll */

	void ConstructL(CBlockTransformation* aBT, CPadding* aPadding);

protected:

	/** A block transformation object */

	CBlockTransformation* iBT;

	/** A descriptor which provides a buffer the length of the block size of iBT */

	HBufC8* iInputStoreBuf;

	/** A pointer to iInputStoreBuf */

	TPtr8 iInputStore;

	/** The padding */

	CPadding* iPadding;

};

/**

 * Subclass of CBufferedTransformation for buffered encryption.

 *

 * Objects of this class are intialised with, and subsequently own, an encryptor

 * derived from CBlockTransformation and a subclass of CPadding.

 *

 */

class CBufferedEncryptor : public CBufferedTransformation

{

public:

	/**

	 * Creates a CBufferedEncryptor object taking ownership of aBT and aPadding.

	 *

	 * @param aBT		Block transformation object (encryptor)

	 * @param aPadding	Padding object (deriving from CPadding)

	 * @return			A pointer to the new CBufferedEncryptor object

	 */

	IMPORT_C static CBufferedEncryptor* NewL(CBlockTransformation* aBT, 

		CPadding* aPadding);

	/**

	 * Creates a CBufferedEncryptor object taking ownership of aBT and aPadding.

	 *

	 * The returned pointer is put onto the cleanup stack.

	 *

	 * @param aBT		Block transformation object (encryptor)

	 * @param aPadding	Padding object (deriving from CPadding)

	 * @return			A pointer to the new CBufferedEncryptor object

	 */

	IMPORT_C static CBufferedEncryptor* NewLC(CBlockTransformation* aBT, 

		CPadding* aPadding);

public:

	/**

	 * Completes an encryption operation using the underlying block transformation, but

	 * first ensuring that input data is block aligned using the previously supplied

	 * CPadding object.  

	 *

	 * See the Cryptography api-guide documentation.

	 *

	 * @param aInput	The final input data to be processed.

	 * @param aOutput	The resulting processed data appended to aOutput.  aOutput must

	 *					have at least MaxFinalOutputLength() empty bytes remaining in its

	 *					length.

	 */

	virtual void ProcessFinalL(const TDesC8& aInput, TDes8& aOutput);

	virtual TInt MaxFinalOutputLength(TInt aInputLength) const;

protected:

	/** @internalAll */

	CBufferedEncryptor();

};

/**

 * Subclass of CBufferedTransformation for buffered decryption.

 *

 * Objects of this class are intialised with, and subsequently own, a decryptor

 * derived from CBlockTransformation and a subclass of CPadding.

 *

 */

class CBufferedDecryptor : public CBufferedTransformation

{

public:

	/**

	 * Creates a CBufferedDecryptor object taking ownership of aBT and aPadding.

	 *

	 * @param aBT		Block transformation object (decryptor)

	 * @param aPadding	Padding object (deriving from CPadding)

	 * @return			A pointer to the CBufferedDecryptor object.

	 */

	IMPORT_C static CBufferedDecryptor* NewL(CBlockTransformation* aBT, 

		CPadding* aPadding);

	/**

	 * Creates a CBufferedDecryptor object taking ownership of aBT and aPadding.

	 *

	 * The returned pointer is put onto the cleanup stack.

	 *

	 * @param aBT		Block transformation object (decryptor)

	 * @param aPadding	Padding object (deriving from CPadding)

	 * @return			A pointer to the new CBufferedDecryptor object

	 */

	IMPORT_C static CBufferedDecryptor* NewLC(CBlockTransformation* aBT, 

		CPadding* aPadding);

public:

	/**

	 * Completes a decryption operation using the underlying block transformation and

	 * unpads the decrypted data.

	 *

	 * @param aInput	The data to be processed and unpadded.  

	 *					aInput must be a whole number of blocks.

	 * @param aOutput	The resulting processed and unpadded data appened to aOutput.

	 *					aOutput must have at least MaxFinalOutputLength() empty bytes

	 *					remaining in its length.

	 */

	virtual void ProcessFinalL(const TDesC8& aInput, TDes8& aOutput);

	virtual TInt MaxFinalOutputLength(TInt aInputLength) const;

protected:

	/** @internalAll */

	CBufferedDecryptor();

};

#endif	//	__CBUFFEREDTRANSFORMATION_H__