/*

 * Copyright (c) 2006-2009 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: 

 *

 */

 #ifndef	ARC4IMPL_H

 #define	ARC4IMPL_H

 /**

 @file 

 @internalComponent

 @released

 */

 #include "symmetriccipherimpl.h"

 #include <e32base.h>

 #include <e32cmn.h>

 #include "keys.h"

 /**

 Plug-in class for ARC4 stream cipher

 */

 namespace SoftwareCrypto

 	{

 	using namespace CryptoSpi;

 	NONSHARABLE_CLASS(CArc4Impl) : public CSymmetricStreamCipherImpl

 		{

 	public:

 		/** 

 		Number of bytes to discard by default from an ARC4 key stream. 

 		*/

 		static const TUint KDefaultDiscardBytes = 768;

 		/** 

 		The size of the substitution box (i.e. lookup table) in bytes. 

 		*/

 		static const TInt KSBoxSize = 256;

 		/** 

 		Maximum ARC4 key size in bytes.2048 bits 

 		*/

 		static const TInt KMaxARC4KeyBytes = 256; 

 		/**

 		Creates an instance of an ARC4 symmetric cipher plug-in.

 		@param aKey The key

 		@param aDiscardBytes The number of bytes to drop from 

 							the beginning of the key stream.

 		@return A pointer to a CArc4Impl instance

 		*/

 		static CArc4Impl* NewL(const CKey& aKey, TInt aDiscardBytes);

 		/**

 		Creates an instance of an ARC4 symmetric cipher plug-in,

 		and leave it on the cleanup stack

 		@param aKey The key

 		@param aDiscardBytes The number of bytes to drop from 

 							the beginning of the key stream.

 		@return A pointer to a CArc4Impl instance

 		*/

 		static CArc4Impl* NewLC(const CKey& aKey, TInt aDiscardBytes);

 		//Destructor

 		~CArc4Impl();

 		//Override MPlugin virtual function

 		void Reset();

 		//Override CSymmetricCipherImpl virtual functions

 		TUid ImplementationUid() const;

 		TBool IsValidKeyLength(TInt aKeyBytes) const;

 		const CExtendedCharacteristics* GetExtendedCharacteristicsL();

 		static CExtendedCharacteristics* CreateExtendedCharacteristicsL();

 	private:

 		//Constructor

 		CArc4Impl(TInt aDiscardBytes);

 		//second phase of construction	

 		void ConstructL(const CKey& aKey);

 		//Override CSymmetricStreamCipherImpl virtual functions

 		void DoProcess(TDes8& aData);	

 		void GenerateSBox();

 		TUint8 GenerateByte();

 		void DiscardBytes(TInt aDiscardBytes);

 	private:

 		TUint8 ix;

 		TUint8 iy;

 		TInt iDiscardBytes;

 		TUint8 iState[KSBoxSize];

 		};

 	}

 #endif //ARC4IMPL_H