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 "dsaverifyimpl.h"
sl@0: #include "pluginconfig.h"
sl@0: 
sl@0: using namespace SoftwareCrypto;
sl@0: 
sl@0: // Implementation of CDSAVerifierImpl
sl@0: CDSAVerifierImpl* CDSAVerifierImpl::NewL(const CKey& aKey)
sl@0: 	{
sl@0: 	CDSAVerifierImpl* self = CDSAVerifierImpl::NewLC(aKey);
sl@0: 	CleanupStack::Pop(self);
sl@0: 	return self;
sl@0: 	}
sl@0: 	
sl@0: CDSAVerifierImpl* CDSAVerifierImpl::NewLC(const CKey& aKey)
sl@0: 	{
sl@0: 	CDSAVerifierImpl* self = new(ELeave) CDSAVerifierImpl();
sl@0: 	CleanupStack::PushL(self);
sl@0: 	self->ConstructL(aKey);
sl@0: 	return self;
sl@0: 	}
sl@0: 	
sl@0: CDSAVerifierImpl::CDSAVerifierImpl() 
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: CDSAVerifierImpl::~CDSAVerifierImpl()
sl@0: 	{
sl@0: 	}
sl@0: 	
sl@0: void CDSAVerifierImpl::ConstructL(const CKey& aKey)
sl@0: 	{
sl@0: 	CVerifierImpl::ConstructL(aKey);
sl@0: 	}
sl@0: 	
sl@0: CExtendedCharacteristics* CDSAVerifierImpl::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* CDSAVerifierImpl::GetExtendedCharacteristicsL()
sl@0: 	{
sl@0: 	return CDSAVerifierImpl::CreateExtendedCharacteristicsL();
sl@0: 	}
sl@0: 	
sl@0: TUid CDSAVerifierImpl::ImplementationUid() const
sl@0: 	{
sl@0: 	return KCryptoPluginDsaVerifierUid;
sl@0: 	}
sl@0: 	
sl@0: void CDSAVerifierImpl::SetKeyL(const CKey& aPublicKey)
sl@0: 	{
sl@0: 	DoSetKeyL(aPublicKey);
sl@0: 	Reset();	
sl@0: 	}
sl@0: 
sl@0: TInt CDSAVerifierImpl::GetMaximumInputLengthL() const
sl@0: 	{
sl@0: 	return KSha1HashLength;
sl@0: 	}
sl@0: 
sl@0: void CDSAVerifierImpl::VerifyL(const TDesC8& aInput, const CCryptoParams& aSignature, TBool& aVerificationResult)
sl@0: 	{
sl@0: 	//Retrieve the parameter Q from the key	
sl@0: 	const TInteger& tQ=iKey->GetBigIntL(KDsaKeyParameterQUid);
sl@0: 
sl@0: 	//see HAC 11.56 or DSS section 6
sl@0: 	//I'll follow HAC as I like the description better
sl@0: 
sl@0: 	// a) Obtain A's authenticate public key
sl@0: 
sl@0: 	// b) Verify that 0 < r < q and 0 < s < q; if not reject signature
sl@0: 
sl@0: 	//Retrieve the R&S in DSA signature from the array
sl@0: 
sl@0: 	const TInteger& tR=aSignature.GetBigIntL(KDsaSignatureParameterRUid);
sl@0: 	const TInteger& tS=aSignature.GetBigIntL(KDsaSignatureParameterSUid);
sl@0: 
sl@0: 	if (tR <= 0 || tR >= tQ)
sl@0: 		{
sl@0: 		aVerificationResult=EFalse;
sl@0: 		return;
sl@0: 		}
sl@0: 	if (tS <= 0 || tS >= tQ)
sl@0: 		{
sl@0: 		aVerificationResult=EFalse;
sl@0: 		return;
sl@0: 		}
sl@0: 		
sl@0: 		
sl@0: 	// c) Compute w = s^(-1) mod q and h(m)
sl@0: 	RInteger w = tS.InverseModL(tQ);
sl@0: 	CleanupStack::PushL(w);
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: 	RInteger hm = RInteger::NewL(aInput);
sl@0: 	CleanupStack::PushL(hm);
sl@0: 
sl@0: 	// d) Compute u1 = w * hm mod q and u2 = r * w mod q
sl@0: 	RInteger u1 = TInteger::ModularMultiplyL(w, hm, tQ);
sl@0: 	CleanupStack::PushL(u1);
sl@0: 
sl@0: 	RInteger u2 = TInteger::ModularMultiplyL(tR, w, tQ);
sl@0: 	CleanupStack::PushL(u2);
sl@0: 
sl@0: 	// e) Compute v = ((g^u1 * y^u2) mod p) mod q
sl@0: 	
sl@0: 	const TInteger& tG=iKey->GetBigIntL(KDsaKeyParameterGUid);
sl@0: 	const TInteger& tY=iKey->GetBigIntL(KDsaKeyParameterYUid);
sl@0: 	const TInteger& tP=iKey->GetBigIntL(KDsaKeyParameterPUid);
sl@0: 
sl@0: 	RInteger temp = TInteger::ModularExponentiateL(tG, u1, tP);
sl@0: 	CleanupStack::PushL(temp);
sl@0: 	RInteger temp1 = TInteger::ModularExponentiateL(tY, u2, tP);
sl@0: 	CleanupStack::PushL(temp1);
sl@0: 	RInteger v = TInteger::ModularMultiplyL(temp, temp1, tP);
sl@0: 	CleanupStack::PushL(v);
sl@0: 	v %= tQ;
sl@0: 
sl@0: 	// f) Accept the signature if v == r
sl@0: 	if(v == tR)
sl@0: 		{
sl@0: 		aVerificationResult = ETrue;
sl@0: 		}
sl@0: 
sl@0: 	CleanupStack::PopAndDestroy(7, &w);
sl@0: 	}
sl@0: 
sl@0: 
sl@0: // Methods which are not supported can be excluded from the coverage.
sl@0: #ifdef _BullseyeCoverage
sl@0: #pragma suppress_warnings on
sl@0: #pragma BullseyeCoverage off
sl@0: #pragma suppress_warnings off
sl@0: #endif
sl@0: 
sl@0: void CDSAVerifierImpl::InverseSignL(HBufC8*& /*aOutput*/, const CCryptoParams& /*aSignature*/)
sl@0: 	{
sl@0: 	// Override in subclass
sl@0: 	User::Leave(KErrNotSupported);
sl@0: 	}