/*+
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* Copyright (c) 2006-2010 Nokia Corporation and/or its subsidiary(-ies).+
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* All rights reserved.+
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* This component and the accompanying materials are made available+
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* under the terms of the License "Eclipse Public License v1.0"+
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* which accompanies this distribution, and is available+
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* at the URL "http://www.eclipse.org/legal/epl-v10.html".+
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*+
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* Initial Contributors:+
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* Nokia Corporation - initial contribution.+
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*+
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* Contributors:+
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*+
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* Description: +
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*+
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*/+
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+
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+
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#ifndef	__SYMMETRICCIPHERIMPL_H__+
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#define	__SYMMETRICCIPHERIMPL_H__+
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+
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/**+
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@file +
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@internalComponent+
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@released+
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*/+
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+
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#include <e32base.h>+
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#include <e32cmn.h>+
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#include <cryptospi/cryptospidef.h>+
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#include <padding.h>+
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#include <cryptospi/symmetriccipherplugin.h>+
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+
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/** The maximum block size supported (in bytes) */+
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const TUint KMaxBlockSizeSupported = 32;+
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+
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/**+
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Abstract base class for symmetric cipher plug-ins.+
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*/+
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namespace SoftwareCrypto+
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	{+
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	using namespace CryptoSpi;+
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		+
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	NONSHARABLE_CLASS(CSymmetricCipherImpl) : public CBase, public MSymmetricCipher+
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		{+
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	public:+
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		/**+
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		Implemented by each cipher subclass to determine whether the+
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		specified key length is valid for that cipher.+
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		This is called by ConstructL and SetKeyL+
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		@param aKeyLength The key length in bytes to verify.+
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		*/+
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		virtual TBool IsValidKeyLength(TInt aKeyBytes) const = 0;+
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		+
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		/**+
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		Helper function implemented by concrete cipher sub-class that +
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		allows GetCharacteristicsL to return the correct characteristics object.+
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		@return The implemention uid+
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		*/+
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		virtual TUid ImplementationUid() const = 0;+
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		+
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		/**+
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		Gets the strength of the current key, needed to check whether the cipher+
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		may operate if strong cryptography is not enabled.+
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		@return The strength of the current key+
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		*/+
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		virtual TInt GetKeyStrength() const;+
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		+
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				+
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		// Override MPlugin virtual functions+
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		void Close();+
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		TAny* GetExtension(TUid aExtensionId);+
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		void GetCharacteristicsL(const TCharacteristics*& aPluginCharacteristics);	+
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		// End of MPlugin+
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		+
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		// Override MSymmetricCipherBase virtual functions +
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		TInt KeySize() const;+
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						+
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		/// Destructor+
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		~CSymmetricCipherImpl();+
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+
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	protected:+
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		+
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		//Constructor+
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		CSymmetricCipherImpl();+
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		+
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		/**+
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		Second phase of construction. Always call ConstructL in the super-class+
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		if your override this method.+
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		+
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		@param aKey The key to initialise the cipher with.+
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		*/+
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		virtual void ConstructL(const CKey& aKey);			+
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		+
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		/**+
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		Extracts the raw symmetric key from a generic key object. The buffer+
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		is placed on the cleanup stack.+
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		+
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		@param aKey The key object+
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		@return A buffer containing the raw key value+
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		*/+
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		HBufC8* ExtractKeyDataLC(const CKey& aKey) const;	+
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	+
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		/**+
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		Zeros a buffer before deleting it to ensure that+
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		the contents will not be visible to another process if the page+
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		is re-used.+
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		@param aBuffer The pointer (possibly null) to the buffer to delete. This+
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		is set to null after deletion.+
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		*/+
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		void SecureDelete(HBufC8*& aBuffer);		+
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					+
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		/**+
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		Extracts the raw key from aKey and sets iKey and iKeyBytes+
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		The key length is also checked to meet export restrictions and+
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		to ensure that it is appropriate for the cipher.+
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		@param aKey The key+
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		*/+
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		virtual void DoSetKeyL(const CKey& aKey);+
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		+
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			+
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	protected:+
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		/// the key, extracted from a CKey object+
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		HBufC8* iKey;+
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		+
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		/// key size in bytes+
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		TUint iKeyBytes;+
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		+
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		};+
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+
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	NONSHARABLE_CLASS(CSymmetricStreamCipherImpl) : public CSymmetricCipherImpl+
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		{+
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	public:+
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		// Destructor+
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		~CSymmetricStreamCipherImpl();+
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		+
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		// Override MSymmetricCipherBase virtual functions +
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		TInt BlockSize() const;+
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		void SetKeyL(const CKey& aKey);		// override DoSetKeyL instead+
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		void SetCryptoModeL(TUid aCryptoMode);+
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		void SetOperationModeL(TUid aOperationMode);+
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		void SetPaddingModeL(TUid aPaddingMode);+
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		void SetIvL(const TDesC8& aIv);+
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		TInt MaxOutputLength(TInt aInputLength) const;+
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		TInt MaxFinalOutputLength(TInt aInputLength) const;+
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		// End of MSymmetricCipherBase+
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		+
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		// Override MSymmetricCipher virtual functions+
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		void ProcessL(const TDesC8& aInput, TDes8& aOutput);+
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		void ProcessFinalL(const TDesC8& aInput, TDes8& aOutput);						+
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		// End of MSymmetricCipher +
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	+
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	protected:+
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		// Constructor+
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		CSymmetricStreamCipherImpl();+
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		+
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		// Override CSymmetricCipherImpl virtual functions+
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		virtual void ConstructL(const CKey& aKey);+
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+
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		/**	+
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		Performs an encryption or decryption on supplied data.+
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		@param aData	On input, data to be transformed; +
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						on return, transformed data.+
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		*/+
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		virtual void DoProcess(TDes8& aData) = 0;+
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		};+
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+
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	NONSHARABLE_CLASS(CSymmetricBlockCipherImpl) : public CSymmetricCipherImpl+
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		{+
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	public:	+
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+
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+
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		/**+
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		This function is invoked by SetKey and SetCryptoMode+
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		allowing the cipher sub-class to rebuild it's key schedule. +
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		N.B. It is assumed that the key schedule is NOT modified+
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		by TransformEncrypt or TransformDecrypt+
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		*/+
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		virtual void SetKeySchedule() = 0;+
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		+
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		// Override MPlugin virtual functions		+
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		void Reset(); // Always call reset in super-class if you override this+
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		// End of MPlugin virtual functions+
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+
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		// Override MSymmetricCipherBase virtual functions +
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		TInt BlockSize() const;+
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		void SetKeyL(const CKey& aKey);  				// override DoSetKeyL instead+
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		void SetCryptoModeL(TUid aCryptoMode);			// override DoSetCryptoModeL instead+
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		void SetOperationModeL(TUid aOperationMode);	// override DoSetOperationMode instead		+
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		void SetPaddingModeL(TUid aPaddingMode);		// override DoSetPaddingModeL instead+
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		void SetIvL(const TDesC8& aIv);+
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		+
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		TInt MaxOutputLength(TInt aInputLength) const;+
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		TInt MaxFinalOutputLength(TInt aInputLength) const;+
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		// End of MSymmetricCipherBase+
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+
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		// Override MSymmetricCipher virtual functions+
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		void ProcessL(const TDesC8& aInput, TDes8& aOutput);+
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		void ProcessFinalL(const TDesC8& aInput, TDes8& aOutput);						+
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		// End of MSymmetricCipher+
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+
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		/// Destructor+
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		~CSymmetricBlockCipherImpl();		+
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	protected:	+
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		/**+
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		Constructor+
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		@param aBlockBytes The block size in bytes+
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		@param aOperationMode The mode of operation e.g. CBC+
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		@param aCryptoMode Whether to encrypt or decrypt+
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		*/+
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		CSymmetricBlockCipherImpl(+
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			TUint8 aBlockBytes,+
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			TUid aOperationMode,+
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			TUid aCryptoMode,+
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			TUid aPaddingMode);+
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			+
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		// Override CSymmetricCipherImpl virtual functions+
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		virtual void ConstructL(const CKey& aKey);+
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+
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		/**+
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		Validates and sets the crypto mode (iCryptoMode)+
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		@param aCryptoMode The crypto mode+
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		*/	+
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		virtual void DoSetCryptoModeL(TUid aCryptoMode);+
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		+
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		/**+
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		Validates and sets the operation mode (iOperationMode)+
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		@param aOperationMode The operation mode+
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		*/+
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		virtual void DoSetOperationModeL(TUid aOperationMode);+
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		+
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		/**+
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		Validates and sets the padding mode (iPaddingMode & iPadding)+
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		@param aPadding The desired padding mode+
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		*/+
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		virtual void DoSetPaddingModeL(TUid aPadding);+
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		+
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		void DoSetIvL(const TDesC8& aIv);+
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+
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		inline void ModeEncryptStart(TUint8* aBuffer);+
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		inline void ModeEncryptEnd(TUint8* aBuffer);+
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		inline void ModeDecryptStart(TUint8* aBuffer);+
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		inline void ModeDecryptEnd(TUint8* aBuffer);+
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+
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	private:+
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	+
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		/**+
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		Encrypts a number of blocks of data+
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		+
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		@param aBuffer The buffer containing exactly aNumBlocks of data to destructively encrypt+
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		@param aNumBlocks The number of blocks of data to encrypt+
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		*/+
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		virtual void TransformEncrypt(TUint8* aBuffer, TUint aNumBlocks) = 0;+
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		+
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		/**+
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		Decrypts a number of blocks of data+
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				+
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		@param aBuffer The buffer containing exactly aNumBlocks of data to destructively decrypt+
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		@param aNumBlocks The number of blocks of data to decrypt+
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		*/+
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		virtual void TransformDecrypt(TUint8* aBuffer, TUint aNumBlocks) = 0;		+
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			+
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		/// Pad the last block and encrypt+
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		void DoProcessFinalEncryptL(const TDesC8& aInput, TDes8& aOutput);+
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		+
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		/// Decrypt and unpad the last block+
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		void DoProcessFinalDecryptL(const TDesC8& aInput, TDes8& aOutput);		+
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		+
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		inline void Transform(TUint8* aBuffer, TUint aNumBlocks);+
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		+
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	protected:+
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	+
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		/// block size in bytes, current largest block size is 16 bytes (AES)+
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		TUint8 iBlockBytes;	+
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		/// encryption or decryption+
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		TUid iCryptoMode;		+
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		/// The block cipher mode e.g. ECB, CBC+
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		TUid iOperationMode;+
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		/// the current padding scheme+
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		TUid iPaddingMode;+
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		+
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		/// the initialisation vector+
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		RBuf8 iIv;+
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		+
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		/// current padding scheme implementation+
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		CPadding* iPadding;+
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		/// buffer to store blocks+
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		RBuf8 iInputStore;+
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		/// buffer to store input / output of padding+
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		RBuf8 iPaddingBlock;+
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+
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		/// The current block of cipher text - for CBC +
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		TUint32* iCurrentCipherText;	+
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		/// A pointer to the current block of cipher text+
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		TUint8* iCurrentCipherTextPtr;		+
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		+
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		/// The result of the transform+
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		TUint32* iCbcRegister;	+
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		/// A pointer to the result of the transform+
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		TUint8* iCbcRegisterPtr;			+
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		};+
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+
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+
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	inline void CSymmetricBlockCipherImpl::Transform(TUint8* aBuffer, TUint aNumBlocks)+
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		{				+
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		if (iCryptoMode.iUid == KCryptoModeEncrypt)+
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			{				+
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			TransformEncrypt(aBuffer, aNumBlocks);+
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			}+
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		else if (iCryptoMode.iUid == KCryptoModeDecrypt)+
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			{				+
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			TransformDecrypt(aBuffer, aNumBlocks);+
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			}+
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		else +
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			{+
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			ASSERT(EFalse);+
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			}+
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		}+
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			+
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	inline void CSymmetricBlockCipherImpl::ModeEncryptStart(TUint8* aBuffer)+
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		{+
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		if (iOperationMode.iUid == KOperationModeCBC)+
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			{			+
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			for (TInt i = 0; i < iBlockBytes; ++i)+
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				{+
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				aBuffer[i] ^= iCbcRegisterPtr[i];+
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				}					+
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			}+
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		}		+
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	+
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	inline void CSymmetricBlockCipherImpl::ModeEncryptEnd(TUint8* aBuffer)+
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		{				+
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		if (iOperationMode.iUid == KOperationModeCBC)+
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			{+
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			for (TInt i = 0; i < iBlockBytes; ++i)+
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				{+
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				iCbcRegisterPtr[i] = aBuffer[i]; +
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				}													+
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			}									+
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		}		+
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+
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	inline void CSymmetricBlockCipherImpl::ModeDecryptStart(TUint8* aBuffer)+
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		{+
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		if (iOperationMode.iUid == KOperationModeCBC)+
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			{			+
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			for (TInt i = 0; i < iBlockBytes; ++i)+
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				{+
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				iCurrentCipherTextPtr[i] = aBuffer[i];+
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				}+
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			}+
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		}+
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+
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	inline void CSymmetricBlockCipherImpl::ModeDecryptEnd(TUint8* aBuffer)+
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		{		+
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		if (iOperationMode.iUid == KOperationModeCBC)+
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			{			+
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			// xor the output with the previous cipher text+
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			for (TInt i = 0; i < iBlockBytes; ++i)+
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				{+
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				aBuffer[i] ^= iCbcRegisterPtr[i];+
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				iCbcRegisterPtr[i] = iCurrentCipherTextPtr[i];+
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				}+
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			}	+
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		}		+
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	}						+
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+
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#endif	//	__SYMMETRICCIPHERIMPL_H__+
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