/*

* 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;

	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