/*

* Copyright (c) 2003-2010 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 <asymmetric.h>

#include <asymmetrickeys.h>

#include <cryptospi/keys.h>

#include "keyconverter.h"

#include <cryptospi/cryptokeyagreementapi.h>

#include <cryptospi/cryptospidef.h>

using namespace CryptoSpi;

CKeyAgreement* GetKeyAgreementCryptoInterfaceLC(TUid aKeyAgreementAlgoUid,

	  CKey& aPrivateKey, CCryptoParams* aParams)

	{

	CKeyAgreement* keyAgreementImpl =  0;

	CKeyAgreementFactory::CreateKeyAgreementL(keyAgreementImpl,

												aKeyAgreementAlgoUid, aPrivateKey,

												aParams);

	CleanupStack::PushL(keyAgreementImpl);

	return keyAgreementImpl;

	}

EXPORT_C CDH* CDH::NewL(const CDHPrivateKey& aPrivateKey)

	{

	CDH* self = CDH::NewLC(aPrivateKey);

	CleanupStack::Pop(self);

	return self;

	}

EXPORT_C CDH* CDH::NewLC(const CDHPrivateKey& aPrivateKey)

	{

	CDH* self = new (ELeave) CDH(aPrivateKey);

	CleanupStack::PushL(self);

	return self;

	}

EXPORT_C HBufC8* CDH::AgreeL(const CDHPublicKey& aPublicKey) const

	{

	/*

	 * both DH keys (ie our private and their public keys) must use the same N and G parameters

	 */

	if ((aPublicKey.N() != iPrivateKey.N()) || (aPublicKey.G() != iPrivateKey.G()))

		{

		User::Leave(KErrArgument);

		}

	CKey* privateKey = KeyConverter::CreateKeyL(iPrivateKey);

	CleanupStack::PushL(privateKey);

	/*

	 *  package the common parameters N and G into a crypto params array

	 * we've already checked that both the private and public keys have the 

	 * same N and G so we only need build this array once for both creating 

	 * and calling the interface

	 */

	CCryptoParams* keyParameters = CCryptoParams::NewLC();

	keyParameters->AddL(aPublicKey.N(), KDhKeyParameterNUid);

	keyParameters->AddL(aPublicKey.G(), KDhKeyParameterGUid);

	/* 

	 * get a DH key agreement interface

	 */

	CKeyAgreement* keyAgreementImpl =  GetKeyAgreementCryptoInterfaceLC(KDHAgreementUid, *privateKey, keyParameters);

	/* 

	 * call the api to get a DH agreed key

	 */

	CKey* publicKey = KeyConverter::CreateKeyL(aPublicKey);

	CleanupStack::PushL(publicKey);

	CKey* agreedKey = keyAgreementImpl->AgreeL(*publicKey, keyParameters);

	CleanupStack::PushL(agreedKey);

	/*

	 * extract the agreed key

	 */

	const TInteger& agreedKeyData = agreedKey->GetBigIntL(KSymmetricKeyParameterUid);

	HBufC8 *agreedKeyToReturn = agreedKeyData.BufferLC();

	CleanupStack::Pop(agreedKeyToReturn);

	/* 

	 * cleanup stack - it should contain privateKey, keyAgreementImpl, publicKey, keyParameters and agreedKey

	 */

	CleanupStack::PopAndDestroy(5, privateKey);

	return agreedKeyToReturn;

	}

EXPORT_C CDH::CDH(const CDHPrivateKey& aPrivateKey) : iPrivateKey(aPrivateKey)

	{

	}