/*

* Copyright (c) 2007-2009 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 "dhkeypairgenimpl.h"

#include "pluginconfig.h"

#include "keypair.h"

using namespace SoftwareCrypto;

using namespace CryptoSpi;

/* CDHKeyPairGenImpl */

CDHKeyPairGenImpl::CDHKeyPairGenImpl()

	{

	}

CDHKeyPairGenImpl::~CDHKeyPairGenImpl()

	{

	}

CDHKeyPairGenImpl* CDHKeyPairGenImpl::NewL(void)

	{

	CDHKeyPairGenImpl* self = CDHKeyPairGenImpl::NewLC();

	CleanupStack::Pop(self);

	return self;

	}

CDHKeyPairGenImpl* CDHKeyPairGenImpl::NewLC(void)

	{

	CDHKeyPairGenImpl* self = new(ELeave) CDHKeyPairGenImpl();

	CleanupStack::PushL(self);

	self->ConstructL();

	return self;

	}

void CDHKeyPairGenImpl::ConstructL(void)

	{

	CKeyPairGenImpl::ConstructL();

	}

CExtendedCharacteristics* CDHKeyPairGenImpl::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* CDHKeyPairGenImpl::GetExtendedCharacteristicsL()

	{

	return CDHKeyPairGenImpl::CreateExtendedCharacteristicsL();

	}

TUid CDHKeyPairGenImpl::ImplementationUid() const

	{

	return KCryptoPluginDhKeyPairGenUid;

	}

void CDHKeyPairGenImpl::Reset()

	{

	// does nothing in this plugin

	}

void CDHKeyPairGenImpl::GenerateKeyPairL(TInt /*aKeySize*/, const CCryptoParams& aKeyParameters, CKeyPair*& aKeyPair)

	{

	/*

	 * unpack the parameters, we're expecting the N and G parameters and if present the x parameter (aka private key)

	 */

	const TInteger& N = aKeyParameters.GetBigIntL(KDhKeyParameterNUid);

	const TInteger& G = aKeyParameters.GetBigIntL(KDhKeyParameterGUid);

	/*

	 * do some sanity checking

	 */

	RInteger nminus2 = RInteger::NewL(N);

	CleanupStack::PushL(nminus2);

	--nminus2;

	--nminus2;

	if ((G < TInteger::Two()) || (G > nminus2))

		{

		User::Leave(KErrArgument);

		}

	/*

	 * has a private key x been supplied? if not then generate it

	 */

	RInteger x;

	if (aKeyParameters.IsPresent(KDhKeyParameterxUid))

		{

		x = RInteger::NewL(aKeyParameters.GetBigIntL(KDhKeyParameterxUid));

		}

		else

		{

		// find a random x | 1 <= x <= n-2

		x = RInteger::NewRandomL(TInteger::One(), nminus2);

		}

	CleanupClosePushL(x);

	/*

	 * generate the public key with X = G^(x) mod N

	 */

	RInteger X = TInteger::ModularExponentiateL(G, x, N);

	CleanupClosePushL(X);

	/*

	 * create the keys parameters

	  */

	CCryptoParams* publicKeyParameters = CCryptoParams::NewLC();

	publicKeyParameters->AddL(X, KDhKeyParameterXUid);

	TKeyProperty publicKeyProperties = {KDHKeyPairGeneratorUid, 	KCryptoPluginDhKeyPairGenUid, 

									KDHPublicKeyUid, KNonEmbeddedKeyUid };

	CCryptoParams* privateKeyParameters = CCryptoParams::NewLC();

	privateKeyParameters->AddL(x, KDhKeyParameterxUid);

	TKeyProperty privateKeyProperties = {KDHKeyPairGeneratorUid, KCryptoPluginDhKeyPairGenUid,

									KDHPrivateKeyUid, KNonEmbeddedKeyUid };

	/*

	 * create the public key

	 */

	CKey* publicKey = CKey::NewL(publicKeyProperties, *publicKeyParameters);

	CleanupStack::PushL(publicKey);

	/*

	 * create the private key

	 */

	CKey* privateKey = CKey::NewL(privateKeyProperties, *privateKeyParameters);

	CleanupStack::PushL(privateKey);

	/*

	 * create the key pair

	 */

	aKeyPair = CKeyPair::NewL(publicKey, privateKey);

	/* 

	 * cleanup stack - it should contain nminus2, x (if allocated here), X, publicKeyParameters, privateKeyParameters, publicKey and privateKey

	 */

	CleanupStack::Pop(2, publicKey);

	CleanupStack::PopAndDestroy(5, &nminus2);

	}