/*

* Copyright (c) 2002-2009 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 "3des.h"

#include "../common/inlines.h"

#include "des.inl"

#include <cryptostrength.h>

const TInt K3DESBlockBytes = 8;

const TInt K3DESKeyBytes = 24;

const TInt KDESKeyBytes = 8;

void C3DES::Transform(TDes8& aBlock)

	{

	assert(aBlock.Size() == K3DESBlockBytes);

	TUint32 l, r;

//	Split the block into 2 word-sized big endian portions

	GetBlockBigEndian((TUint8*)&aBlock[0], l, r);

	IPerm(l,r);

	DoTransform(l, r, iK1);

	DoTransform(r, l, iK2);

	DoTransform(l, r, iK3);

	FPerm(l,r);

//	Put the portions back into the block as little endian

	PutBlockBigEndian((TUint8*)&aBlock[0], r, l);

	}

TInt C3DES::BlockSize() const

	{

	return K3DESBlockBytes;

	}

TInt C3DES::KeySize() const

	{

	return K3DESKeyBytes;

	}

C3DES::C3DES()

	{

	}

void C3DES::ConstructL(const TDesC8& aKey)

	{

	assert(aKey.Size() == K3DESKeyBytes);

	iKey = aKey.AllocL();

	DoSetKey(*iKey);

	}

void C3DES::Reset()

	{

	DoSetKey(*iKey);

	}

/* C3DESEncryptor */

EXPORT_C C3DESEncryptor* C3DESEncryptor::NewL(const TDesC8& aKey)

	{

	C3DESEncryptor* me = C3DESEncryptor::NewLC(aKey);

	CleanupStack::Pop(me);

	return (me);	

	}

EXPORT_C C3DESEncryptor* C3DESEncryptor::NewLC(const TDesC8& aKey)

	{

	C3DESEncryptor* me = new (ELeave) C3DESEncryptor();

	CleanupStack::PushL(me);

	me->ConstructL(aKey);

	// DES only used 7 bits out of every key byte

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

	return (me);	

	}

void C3DESEncryptor::DoSetKey(const TDesC8& aKey)

	{

	// Encryptor key	

	SetKey(aKey.Mid(0, KDESKeyBytes), iK1);

	// Decryptor key

	SetKey(aKey.Mid(KDESKeyBytes, 2*KDESKeyBytes), iK2);

	ReverseKeySchedule(iK2); // Reverse key schedule order

	// Encryptor key

	SetKey(aKey.Mid(2*KDESKeyBytes), iK3);

	}

/* C3DESDecryptor */

EXPORT_C C3DESDecryptor* C3DESDecryptor::NewL(const TDesC8& aKey)

	{

	C3DESDecryptor* me = C3DESDecryptor::NewLC(aKey);

	CleanupStack::Pop(me);

	return (me);

	}

EXPORT_C C3DESDecryptor* C3DESDecryptor::NewLC(const TDesC8& aKey)

	{

	C3DESDecryptor* me = new (ELeave) C3DESDecryptor();

	CleanupStack::PushL(me);

	me->ConstructL(aKey);

	// DES only used 7 bits out of every key byte

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

	return (me);

	}

void C3DESDecryptor::DoSetKey(const TDesC8& aKey)

	{

	// 3DES decryption, reverse through key

	// Decryptor key

	CDES::SetKey(aKey.Mid(2*KDESKeyBytes), iK1);

	ReverseKeySchedule(iK1);	//	Reverse key schedule order	

	// Encryptor key

	CDES::SetKey(aKey.Mid(KDESKeyBytes, 2*KDESKeyBytes), iK2);

	// Decryptor key

	CDES::SetKey(aKey.Mid(0, KDESKeyBytes), iK3);

	ReverseKeySchedule(iK3);	//	Reverse key schedule order

	}