/*

* 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: 

*

*/

#include "arc4impl.h"

#include "keys.h"

#include "pluginconfig.h"

#include "symmetriccipherimpl.h"

#include <cryptostrength.h>

#include "common/inlines.h"

using namespace SoftwareCrypto;

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

	{

	CArc4Impl* self = CArc4Impl::NewLC(aKey, aDiscardBytes);

	CleanupStack::Pop(self);

	return self;		

	}

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

	{

	CArc4Impl* self = new(ELeave) CArc4Impl(aDiscardBytes);

	CleanupStack::PushL(self);

	self->ConstructL(aKey);

	const TDesC8& keyContent = aKey.GetTDesC8L(KSymmetricKeyParameterUid);

	TCrypto::IsSymmetricWeakEnoughL(BytesToBits(keyContent.Size()) - keyContent.Size());

	return self;		

	}

CArc4Impl::CArc4Impl(TInt aDiscardBytes)

:ix(1), iy(0), iDiscardBytes(aDiscardBytes)

	{

	}

CArc4Impl::~CArc4Impl()

	{

	}

void CArc4Impl::ConstructL(const CKey& aKey)

	{

	CSymmetricStreamCipherImpl::ConstructL(aKey);

	GenerateSBox();

	}

CExtendedCharacteristics* CArc4Impl::CreateExtendedCharacteristicsL()

	{

	// All Symbian software plug-ins have unlimited concurrency, cannot be reserved

	// for exclusive use and are not CERTIFIED to be standards compliant.

	return CExtendedCharacteristics::NewL(KMaxTInt, EFalse);

	}

const CExtendedCharacteristics* CArc4Impl::GetExtendedCharacteristicsL()

	{

	return CArc4Impl::CreateExtendedCharacteristicsL();

	}

void CArc4Impl::DoProcess(TDes8& aData)

	{

	TInt blockLen = aData.Size();

	if (blockLen > 0)

		{

		TUint8* blockPtr = (TUint8*)&aData[0];	

		do

			{

			*blockPtr++ ^= GenerateByte();

			} 

		while (--blockLen);

		}

	}

TBool CArc4Impl::IsValidKeyLength(TInt aKeyBytes) const

	{

	return ((aKeyBytes > 0 && aKeyBytes <= KMaxARC4KeyBytes) ? ETrue : EFalse);

	}

void CArc4Impl::Reset()

	{

	ix = 1;

	iy = 0;

	GenerateSBox();

	}

TUid CArc4Impl::ImplementationUid() const

	{

	return KCryptoPluginArc4Uid;

	}

TUint8 CArc4Impl::GenerateByte()

	{

	TUint8 a = iState[ix];

	iy = (TUint8)((iy + a) & 0xff);

	TUint8 b = iState[iy];

	iState[ix] = b;

	iState[iy] = a;

	ix = (TUint8)((ix + 1) & 0xff);

	return (iState[(a + b) & 0xff]);

	}

void CArc4Impl::DiscardBytes(TInt aDiscardBytes)

	{	

	if (aDiscardBytes > 0)

		{

		do

			{

			GenerateByte();

			}

		while(--aDiscardBytes);

		}

	}

void CArc4Impl::GenerateSBox(void)

	{

	TUint keyBytes = iKey->Size();

	TInt i = 0;

	for (; i < KSBoxSize; i++)

		iState[i] = (TUint8)i;

	TUint keyIndex = 0, stateIndex = 0;

	i = 0;

	for (; i < KSBoxSize; i++)

		{

		TUint a = iState[i];

		stateIndex += (*iKey)[keyIndex] + a;

		stateIndex &= 0xff;

		iState[i] = iState[stateIndex];

		iState[stateIndex] = (TUint8)a;

		if (++keyIndex >= (TUint)keyBytes)

			keyIndex = 0;

		}

	DiscardBytes(iDiscardBytes);

	}