sl@0: /*
sl@0: * Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: * All rights reserved.
sl@0: * This component and the accompanying materials are made available
sl@0: * under the terms of the License "Eclipse Public License v1.0"
sl@0: * which accompanies this distribution, and is available
sl@0: * at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: *
sl@0: * Initial Contributors:
sl@0: * Nokia Corporation - initial contribution.
sl@0: *
sl@0: * Contributors:
sl@0: *
sl@0: * Description: 
sl@0: *
sl@0: */
sl@0: 
sl@0: 
sl@0: #include "arc4impl.h"
sl@0: #include "keys.h"
sl@0: #include "pluginconfig.h"
sl@0: #include "symmetriccipherimpl.h"
sl@0: #include <cryptostrength.h>
sl@0: #include "common/inlines.h"
sl@0: 
sl@0: 
sl@0: using namespace SoftwareCrypto;
sl@0: 
sl@0: CArc4Impl* CArc4Impl::NewL(const CKey& aKey, TInt aDiscardBytes)
sl@0: 	{
sl@0: 	CArc4Impl* self = CArc4Impl::NewLC(aKey, aDiscardBytes);
sl@0: 	CleanupStack::Pop(self);
sl@0: 	return self;		
sl@0: 	}
sl@0: 
sl@0: CArc4Impl* CArc4Impl::NewLC(const CKey& aKey, TInt aDiscardBytes)
sl@0: 	{
sl@0: 	CArc4Impl* self = new(ELeave) CArc4Impl(aDiscardBytes);
sl@0: 	CleanupStack::PushL(self);
sl@0: 	self->ConstructL(aKey);
sl@0: 	
sl@0: 	const TDesC8& keyContent = aKey.GetTDesC8L(KSymmetricKeyParameterUid);
sl@0: 	TCrypto::IsSymmetricWeakEnoughL(BytesToBits(keyContent.Size()) - keyContent.Size());
sl@0: 
sl@0: 	return self;		
sl@0: 	}
sl@0: 
sl@0: CArc4Impl::CArc4Impl(TInt aDiscardBytes)
sl@0: :ix(1), iy(0), iDiscardBytes(aDiscardBytes)
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: CArc4Impl::~CArc4Impl()
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: void CArc4Impl::ConstructL(const CKey& aKey)
sl@0: 	{
sl@0: 	CSymmetricStreamCipherImpl::ConstructL(aKey);
sl@0: 	GenerateSBox();
sl@0: 	}
sl@0: 
sl@0: CExtendedCharacteristics* CArc4Impl::CreateExtendedCharacteristicsL()
sl@0: 	{
sl@0: 	// All Symbian software plug-ins have unlimited concurrency, cannot be reserved
sl@0: 	// for exclusive use and are not CERTIFIED to be standards compliant.
sl@0: 	return CExtendedCharacteristics::NewL(KMaxTInt, EFalse);
sl@0: 	}
sl@0: 	
sl@0: const CExtendedCharacteristics* CArc4Impl::GetExtendedCharacteristicsL()
sl@0: 	{
sl@0: 	return CArc4Impl::CreateExtendedCharacteristicsL();
sl@0: 	}
sl@0: 
sl@0: void CArc4Impl::DoProcess(TDes8& aData)
sl@0: 	{
sl@0: 	TInt blockLen = aData.Size();
sl@0: 
sl@0: 	if (blockLen > 0)
sl@0: 		{
sl@0: 		TUint8* blockPtr = (TUint8*)&aData[0];	
sl@0: 		do
sl@0: 			{
sl@0: 			*blockPtr++ ^= GenerateByte();
sl@0: 			} 
sl@0: 		while (--blockLen);
sl@0: 		}
sl@0: 	}
sl@0: 	
sl@0: TBool CArc4Impl::IsValidKeyLength(TInt aKeyBytes) const
sl@0: 	{
sl@0: 	return ((aKeyBytes > 0 && aKeyBytes <= KMaxARC4KeyBytes) ? ETrue : EFalse);
sl@0: 	}
sl@0: 
sl@0: void CArc4Impl::Reset()
sl@0: 	{
sl@0: 	ix = 1;
sl@0: 	iy = 0;
sl@0: 	GenerateSBox();
sl@0: 	}
sl@0: 
sl@0: TUid CArc4Impl::ImplementationUid() const
sl@0: 	{
sl@0: 	return KCryptoPluginArc4Uid;
sl@0: 	}
sl@0: 	
sl@0: TUint8 CArc4Impl::GenerateByte()
sl@0: 	{
sl@0: 	TUint8 a = iState[ix];
sl@0: 	iy = (TUint8)((iy + a) & 0xff);
sl@0: 	TUint8 b = iState[iy];
sl@0: 
sl@0: 	iState[ix] = b;
sl@0: 	iState[iy] = a;
sl@0: 	ix = (TUint8)((ix + 1) & 0xff);
sl@0: 	return (iState[(a + b) & 0xff]);
sl@0: 	}
sl@0: 
sl@0: void CArc4Impl::DiscardBytes(TInt aDiscardBytes)
sl@0: 	{	
sl@0: 	if (aDiscardBytes > 0)
sl@0: 		{
sl@0: 		do
sl@0: 			{
sl@0: 			GenerateByte();
sl@0: 			}
sl@0: 		while(--aDiscardBytes);
sl@0: 		}
sl@0: 	}
sl@0: 
sl@0: void CArc4Impl::GenerateSBox(void)
sl@0: 	{
sl@0: 	TUint keyBytes = iKey->Size();
sl@0: 		
sl@0: 	TInt i = 0;
sl@0: 	for (; i < KSBoxSize; i++)
sl@0: 		iState[i] = (TUint8)i;
sl@0: 	
sl@0: 	TUint keyIndex = 0, stateIndex = 0;
sl@0: 	i = 0;
sl@0: 	for (; i < KSBoxSize; i++)
sl@0: 		{
sl@0: 		TUint a = iState[i];
sl@0: 		stateIndex += (*iKey)[keyIndex] + a;
sl@0: 		stateIndex &= 0xff;
sl@0: 		iState[i] = iState[stateIndex];
sl@0: 		iState[stateIndex] = (TUint8)a;
sl@0: 		if (++keyIndex >= (TUint)keyBytes)
sl@0: 			keyIndex = 0;
sl@0: 		}
sl@0: 
sl@0: 	DiscardBytes(iDiscardBytes);
sl@0: 	}