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 "dsasignerimpl.h"
sl@0: #include "pluginconfig.h"
sl@0: 
sl@0: using namespace SoftwareCrypto;
sl@0: 
sl@0: // Implementation of CDSASignerImpl 
sl@0: CDSASignerImpl* CDSASignerImpl::NewL(const CKey& aKey)
sl@0: 	{
sl@0: 	CDSASignerImpl* self = CDSASignerImpl::NewLC(aKey);
sl@0: 	CleanupStack::Pop(self);
sl@0: 	return self;
sl@0: 	}
sl@0: 	
sl@0: CDSASignerImpl* CDSASignerImpl::NewLC(const CKey& aKey)
sl@0: 	{
sl@0: 	CDSASignerImpl* self = new(ELeave) CDSASignerImpl();
sl@0: 	CleanupStack::PushL(self);
sl@0: 	self->ConstructL(aKey);
sl@0: 	return self;
sl@0: 	}
sl@0: 
sl@0: CDSASignerImpl::CDSASignerImpl() 
sl@0: 	{
sl@0: 	}
sl@0: 	
sl@0: CDSASignerImpl::~CDSASignerImpl()
sl@0: 	{
sl@0: 	}
sl@0: 	
sl@0: void CDSASignerImpl::ConstructL(const CKey& aKey)
sl@0: 	{
sl@0: 	CSignerImpl::ConstructL(aKey);
sl@0: 	}
sl@0: 
sl@0: CExtendedCharacteristics* CDSASignerImpl::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* CDSASignerImpl::GetExtendedCharacteristicsL()
sl@0: 	{
sl@0: 	return CDSASignerImpl::CreateExtendedCharacteristicsL();
sl@0: 	}
sl@0: 
sl@0: TUid CDSASignerImpl::ImplementationUid() const
sl@0: 	{
sl@0: 	return KCryptoPluginDsaSignerUid;
sl@0: 	}
sl@0: 	
sl@0: void CDSASignerImpl::SetKeyL(const CKey& aPrivateKey) 
sl@0: 	{
sl@0: 	DoSetKeyL(aPrivateKey);
sl@0: 	Reset();
sl@0: 	}
sl@0: 
sl@0: TInt CDSASignerImpl::GetMaximumInputLengthL() const 
sl@0: 	{
sl@0: 	return KSha1HashLength;
sl@0: 	}
sl@0: 
sl@0: void CDSASignerImpl::SignL(const TDesC8& aInput, CCryptoParams& aSignature) 
sl@0: 	{
sl@0: 	
sl@0: 	//see HAC 11.56 or DSS section 5
sl@0: 	//I'll follow HAC as I like its description better
sl@0: 	//We don't check that r and s are non both non-null like the DSS
sl@0: 	//states you _optionally_ can.  The chances of this are _incredibly_ small.
sl@0: 	//You've got a much better chance of a bit failure ocurring in the hardware
sl@0: 	//than this.
sl@0: 
sl@0: 	const TInteger& tQ=iKey->GetBigIntL(KDsaKeyParameterQUid);
sl@0: 		
sl@0: 	// a) Select a random secret integer (k | 0 < k < q)
sl@0: 	RInteger qminus1 = RInteger::NewL(tQ);
sl@0: 	CleanupStack::PushL(qminus1);
sl@0: 	--qminus1;
sl@0: 	RInteger k = RInteger::NewRandomL(TInteger::One(), qminus1);
sl@0: 	CleanupStack::PopAndDestroy(&qminus1);
sl@0: 	CleanupStack::PushL(k);
sl@0: 	
sl@0: 	
sl@0: 	// b) compute r = (g^k mod p) mod q
sl@0: 	
sl@0: 	const TInteger& tG=iKey->GetBigIntL(KDsaKeyParameterGUid);
sl@0: 	const TInteger& tP=iKey->GetBigIntL(KDsaKeyParameterPUid);
sl@0: 	RInteger r = TInteger::ModularExponentiateL(tG, k, tP);
sl@0: 	CleanupStack::PushL(r);
sl@0: 	r %=tQ;
sl@0: 	
sl@0: 	
sl@0: 	// c) compute k^(-1) mod q
sl@0: 
sl@0: 	RInteger kinv = k.InverseModL(tQ);
sl@0: 	CleanupStack::PushL(kinv);
sl@0: 
sl@0: 
sl@0: 	// d) compute s = k^(-1) * {h(m) + xr} mod q
sl@0: 	// Note that in order to be interoperable, compliant with the DSS, and
sl@0: 	// secure, aInput must be the result of a SHA-1 hash
sl@0: 
sl@0: 	RInteger hm = RInteger::NewL(aInput);
sl@0: 	CleanupStack::PushL(hm);
sl@0: 	
sl@0: 	const TInteger& tX=iKey->GetBigIntL(KDsaKeyParameterXUid);	
sl@0: 	RInteger s = tX.TimesL(r);
sl@0: 	CleanupStack::PushL(s);
sl@0: 	s += hm;
sl@0: 	s *= kinv;
sl@0: 	s %= tQ;
sl@0: 
sl@0: 
sl@0: 	// e) signature for m is the pair (r,s)
sl@0: 	aSignature.AddL(r, KDsaSignatureParameterRUid);
sl@0: 	aSignature.AddL(s, KDsaSignatureParameterSUid);
sl@0: 	
sl@0: 	CleanupStack::PopAndDestroy(5, &k);
sl@0: 	}