/*

* 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: 

* RSA Keypair implementation

* RSA keypair generation implementation

*

*/

/**

 @file

*/

#include "rsakeypairgenimpl.h"

#include "pluginconfig.h"

#include "keypair.h"

#include <cryptospi/cryptospidef.h>

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

using namespace SoftwareCrypto;

/* CRSAKeyPairGenImpl */

CRSAKeyPairGenImpl::CRSAKeyPairGenImpl()

	{

	}

CRSAKeyPairGenImpl::~CRSAKeyPairGenImpl()

	{

	}

CRSAKeyPairGenImpl* CRSAKeyPairGenImpl::NewL(void)

	{

	CRSAKeyPairGenImpl* self = CRSAKeyPairGenImpl::NewLC();

	CleanupStack::Pop(self);

	return self;

	}

CRSAKeyPairGenImpl* CRSAKeyPairGenImpl::NewLC(void)

	{

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

	CleanupStack::PushL(self);

	self->ConstructL();

	return self;

	}

void CRSAKeyPairGenImpl::ConstructL(void)

	{

	CKeyPairGenImpl::ConstructL();

	}

CExtendedCharacteristics* CRSAKeyPairGenImpl::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* CRSAKeyPairGenImpl::GetExtendedCharacteristicsL()

	{

	return CRSAKeyPairGenImpl::CreateExtendedCharacteristicsL();

	}

TUid CRSAKeyPairGenImpl::ImplementationUid() const

	{

	return KCryptoPluginRsaKeyPairGenUid;

	}

void CRSAKeyPairGenImpl::Reset()

	{

	// does nothing in this plugin

	}

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

	{

	/*

	 * extract e

	 */ 

	const TInt aKeyType = aKeyParameters.GetTIntL(KRsaKeyTypeUid);

	const TInt aPublicExponent = aKeyParameters.GetTIntL(KRsaKeyParameterEUid);

	RInteger e = RInteger::NewL(aPublicExponent);

	CleanupStack::PushL(e);

	/*

	 * calculate p, q, n & d

	 */ 

	RInteger p;

	RInteger q;

	//these make sure n is a least aKeySize long

	TInt pbits=(aKeySize+1)/2;

	TInt qbits=aKeySize-pbits;

	//generate a prime p such that GCD(e,p-1) == 1

	for (;;)

		{

		p = RInteger::NewPrimeL(pbits,TInteger::ETop2BitsSet);

		CleanupStack::PushL(p);

		--p;

		RInteger gcd = e.GCDL(p);

		if( gcd == 1 )

			{

			++p;

			gcd.Close();

			//p is still on cleanup stack

			break;

			}

		CleanupStack::PopAndDestroy(&p);

		gcd.Close();

		}

	//generate a prime q such that GCD(e,q-1) == 1 && (p != q)

	for (;;)

		{

		q = RInteger::NewPrimeL(qbits,TInteger::ETop2BitsSet);

		CleanupStack::PushL(q);

		--q;

		RInteger gcd = e.GCDL(q);

		if( gcd == 1 )

			{

			++q;

			if( p != q )

				{

				gcd.Close();

				//q is still on cleanup stack

				break;

				}

			}

		CleanupStack::PopAndDestroy(&q);

		gcd.Close();

		}

	//make sure p > q

	if ( p < q)

		{

		TClassSwap(p,q);

		}

	//calculate n = p * q

	RInteger n = p.TimesL(q);

	CleanupStack::PushL(n);

	--p;

	--q;

	//temp = (p-1)(q-1)

	RInteger temp = p.TimesL(q);

	CleanupStack::PushL(temp);

	//e * d = 1 mod ((p-1)(q-1))

	//d = e^(-1) mod ((p-1)(q-1))

	RInteger d = e.InverseModL(temp);

	CleanupStack::PopAndDestroy(&temp); //temp

	CleanupStack::PushL(d);

	/*

	 * create private key depending on aKeyType

	 */ 

	CCryptoParams* privateKeyParameters = CCryptoParams::NewLC();

	privateKeyParameters->AddL(n, KRsaKeyParameterNUid);

	TKeyProperty* privateKeyProperties = NULL;

	TKeyProperty privateKeyProperties_RsaPrivateKeyCRT = {KRSAKeyPairGeneratorUid, KCryptoPluginRsaKeyPairGenUid,

									KRsaPrivateKeyCRTUid, KNonEmbeddedKeyUid };

	TKeyProperty privateKeyProperties_RsaPrivateKeyStandard = {KRSAKeyPairGeneratorUid, KCryptoPluginRsaKeyPairGenUid,

									KRsaPrivateKeyStandardUid, KNonEmbeddedKeyUid };

	CCryptoParams*publicKeyParameters = CCryptoParams::NewLC();

	publicKeyParameters->AddL(n, KRsaKeyParameterNUid);

	publicKeyParameters->AddL(e, KRsaKeyParameterEUid);

	TKeyProperty publicKeyProperties = {KRSAKeyPairGeneratorUid, KCryptoPluginRsaKeyPairGenUid,

									KRsaPublicKeyUid, KNonEmbeddedKeyUid };

	if (aKeyType == KRsaPrivateKeyCRT)			// cleanup stack contains e, p, q, n, d and privateKeyParameters

	{

		/*

		 * calculate dP, dQ and qInv

		 */ 

		//calculate dP = d mod (p-1)

		RInteger dP = d.ModuloL(p); //p is still p-1

		CleanupStack::PushL(dP);

		privateKeyParameters->AddL(dP, KRsaKeyParameterDPUid);

		CleanupStack::PopAndDestroy(&dP);

		//calculate dQ = d mod (q-1)

		RInteger dQ = d.ModuloL(q); //q is still q-1

		CleanupStack::PushL(dQ);

		privateKeyParameters->AddL(dQ, KRsaKeyParameterDQUid);

		CleanupStack::PopAndDestroy(&dQ);

		++p;

		++q;

		//calculate inverse of qInv = q^(-1)mod(p)

		RInteger qInv = q.InverseModL(p);

		CleanupStack::PushL(qInv);

		privateKeyParameters->AddL(qInv, KRsaKeyParameterQInvUid);

		CleanupStack::PopAndDestroy(&qInv);

		privateKeyParameters->AddL(p, KRsaKeyParameterPUid);

		privateKeyParameters->AddL(q, KRsaKeyParameterQUid);

		privateKeyProperties = &privateKeyProperties_RsaPrivateKeyCRT;

	}

	else if (aKeyType == KRsaPrivateKeyStandard)

	{

		privateKeyParameters->AddL(d, KRsaKeyParameterDUid);

		privateKeyProperties = &privateKeyProperties_RsaPrivateKeyStandard;

	}

	else

	{

		User::Leave(KErrNotSupported);

	}

	// cleanup stack contains e, p, q, n, d and privateKeyParameters

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

	CleanupStack::PushL(privateKey);

	/*

	 * create public key

	 */

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

	CleanupStack::PushL(publicKey);

	/*

	* create the key pair

	*/

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

	CleanupStack::Pop(2, privateKey); //privateKey and publicKey

	CleanupStack::PopAndDestroy(7, &e); //e, p, q, n, d, privateKeyParameters and publicKeyParameters

	}