/*

 * Copyright (c) 1998-2009 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 "pkixCons.h"

 //PKIX constraint

 //only function is remove

 TPKIXConstraint::TPKIXConstraint(	CPKIXValidationState& aState, 

 									CPKIXValidationResultBase& aResult)

 	:iState(aState), iResult(aResult)

 	{

 	}

 void TPKIXConstraint::Remove(CArrayPtrFlat<CX509CertExtension>& aCriticalExtensions, const TDesC& aOID)

 	{

 	TInt count = aCriticalExtensions.Count();

 	for (TInt i = 0; i < count; i++)

 		{

 		CX509CertExtension* ext = aCriticalExtensions.At(i);

 		if (ext->Id() == aOID)

 			{

 			aCriticalExtensions.Delete(i);

 			break;

 			}

 		}

 	}

 //policy constraint

 //public functions

 TPKIXPolicyConstraint::TPKIXPolicyConstraint(	CPKIXValidationState& aState, 

 												CPKIXValidationResultBase& aResult)

 	:TPKIXConstraint(aState, aResult)

 	{

 	}

 void TPKIXPolicyConstraint::CleanupPolicyInfoArray(TAny* aPolicies)

 	{

 	CArrayPtrFlat<CX509CertPolicyInfo>* array = REINTERPRET_CAST(CArrayPtrFlat<CX509CertPolicyInfo>*, aPolicies);

 	array->ResetAndDestroy();

 	delete array;

 	}

 void TPKIXPolicyConstraint::CheckCertPoliciesL(const CX509Certificate& aCert)

 	{

 	const CX509CertExtension* ext =  aCert.Extension(KCertPolicies);

 	CX509CertPoliciesExt* policyExt = NULL;

 	if (ext)

 		{

 		policyExt = CX509CertPoliciesExt::NewLC(ext->Data());

 		}

 	if (iState.iPos > iState.iPolicyRequired)

 		{

 		if (!(policyExt))

 			{

 			iResult.SetErrorAndLeaveL(ERequiredPolicyNotFound, iState.iPos);

 			}

 		const CArrayPtrFlat<CX509CertPolicyInfo>& policies = policyExt->Policies();

 		if ((iState.iUserPolicies->Count() == 0) || (PolicyIsPresentL(policies, *iState.iUserPolicies)))

 			{

 			}

 		else

 			{

 			iResult.SetErrorAndLeaveL(ERequiredPolicyNotFound, iState.iPos);

 			}

 		}

 	if (!policyExt)

 		{

 		if (!iState.iAnyAuthorityPolicy)

 			{

 			iState.iAuthorityConstrainedPolicies->ResetAndDestroy();//AP becomes NULL 

 			}

 		}

 	else

 		{

 		IntersectCertPoliciesL(*policyExt);

 		if (ext->Critical())

 			{

 			TInt count = iState.iAuthorityConstrainedPolicies->Count();

 			for (TInt i = 0; i < count; i++)

 				{

 				const CX509CertPolicyInfo* policy = iState.iAuthorityConstrainedPolicies->At(i);

 				if (policy->Qualifiers().Count() > 0)

 					{

 					iResult.AppendWarningL(TValidationStatus(ECriticalCertPoliciesWithQualifiers, i));

 					break;

 					}

 				}

 			Remove(*(iState.iCriticalExts), KCertPolicies);

 			}

 		CleanupStack::PopAndDestroy();//policyExt

 		}		

 	}

 void TPKIXPolicyConstraint::IntersectCertPoliciesL(const CX509CertPoliciesExt& aPolicyExt)

 	{

 	//1 intersect AP and CP, assign result to newAP

 	CArrayPtrFlat<CX509CertPolicyInfo>* newAP;

 	TInt certPolicyCount = aPolicyExt.Policies().Count();

 	if (iState.iAnyAuthorityPolicy)

 		{

 		newAP = new(ELeave) CArrayPtrFlat<CX509CertPolicyInfo> (1);

 		TCleanupItem cleanupPolicies(CleanupPolicyInfoArray, newAP);

 		CleanupStack::PushL(cleanupPolicies);

 		for (TInt i = 0; i < certPolicyCount; i++)

 			{

 			CX509CertPolicyInfo* info = CX509CertPolicyInfo::NewLC(*(aPolicyExt.Policies().At(i)));

 			newAP->AppendL(info);

 			CleanupStack::Pop();

 			}

 		iState.iAnyAuthorityPolicy = EFalse;

 		}

 	else

 		{			

 		newAP = IntersectionLC(aPolicyExt.Policies(), *(iState.iAuthorityConstrainedPolicies));

 		}

 	TInt mappedCount = iState.iMappedPolicies->Count(); 

 	for (TInt i = 0; i < mappedCount; i++)

 		{

 		CX509PolicyMapping* mapping = iState.iMappedPolicies->At(i);

 		TInt apCount = iState.iAuthorityConstrainedPolicies->Count();

 	//2 for each mapping in MP, if issuer is in AP and subject is in CP, add subject to newAP

 		for (TInt j = 0; j < apCount; j++)

 			{

 			CX509CertPolicyInfo* aCP = iState.iAuthorityConstrainedPolicies->At(j);

 			if (aCP->Id() == mapping->IssuerPolicy())

 				{

 				for (TInt k = 0; k < certPolicyCount; k++)

 					{

 					CX509CertPolicyInfo* cp = aPolicyExt.Policies().At(k);

 					if (mapping->SubjectPolicy() == cp->Id())

 						{

 						CX509CertPolicyInfo* newPolicy = CX509CertPolicyInfo::NewLC(*cp);

 						newAP->AppendL(newPolicy);

 						CleanupStack::Pop();

 						}

 					}

 				}

 			}

 		}

 	//new acceptable policies  = intersection

 	iState.iAuthorityConstrainedPolicies->ResetAndDestroy(); 

 	delete iState.iAuthorityConstrainedPolicies;

 	iState.iAuthorityConstrainedPolicies = newAP;

 	CleanupStack::Pop();//newAP

 	}

 void TPKIXPolicyConstraint::UpdatePolicyConstraintsL(const CX509Certificate& aCert)

 	{

 	//get mapping ext

 	const CX509CertExtension* ext = aCert.Extension(KPolicyMapping);

 	if ((iState.iPos <= iState.iPolicyMapping) && (ext))

 		{

 		CX509PolicyMappingExt* policyMappingExt = CX509PolicyMappingExt::NewLC(ext->Data());

 		const CArrayPtrFlat<CX509PolicyMapping>& mappings = policyMappingExt->Mappings();

 		//for each policy mapping

 		TInt countM = mappings.Count();

 		for (TInt i = 0; i < countM; i++)

 			{

 			CX509PolicyMapping* mapping = mappings.At(i);

 			CX509PolicyMapping* newMapping = CX509PolicyMapping::NewLC(*mapping);

 			iState.iMappedPolicies->AppendL(newMapping);

 			CleanupStack::Pop();

 			TInt uCount = iState.iUserPolicies->Count();

 			for (TInt j = 0; j < uCount; j++)

 				{

 				HBufC* userPolicy = iState.iUserPolicies->At(j);

 				if (newMapping->IssuerPolicy() == *userPolicy)

 					{

 					HBufC* newUP = newMapping->SubjectPolicy().AllocL();

 					CleanupStack::PushL(newUP);

 					iState.iUserPolicies->AppendL(newUP);

 					CleanupStack::Pop();

 					break;

 					}

 				}

 			}

 		CleanupStack::PopAndDestroy();//mapping ext

 		}

 	iState.iPolicyMapping --;

 	iState.iPolicyRequired --;

 	//get constraints 

 	ext = aCert.Extension(KPolicyConstraints);

 	if ( ext )

 		{

 		CX509PolicyConstraintsExt* policyConstraintsExt = CX509PolicyConstraintsExt::NewLC(ext->Data());

 		UpdateConstraint(policyConstraintsExt->InhibitPolicyMapping(), iState.iPolicyMapping);

 		UpdateConstraint(policyConstraintsExt->ExplicitPolicyRequired(), iState.iPolicyRequired);

 		CleanupStack::PopAndDestroy();//constraint ext

 		//remove it from the 'critical list'

 		if (ext->Critical())

 			{

 			Remove(*(iState.iCriticalExts), KPolicyConstraints);

 			}	

 		}

 	}

 //private functions

 TBool TPKIXPolicyConstraint::PolicyIsPresentL(	const CArrayPtrFlat<CX509CertPolicyInfo>& aPolicies,

 												const CArrayPtr<HBufC>& aAcceptablePolicies)

 	{

 	TInt certCount = aPolicies.Count();

 	TInt chainCount = aAcceptablePolicies.Count();

 	for (TInt i = 0; i < certCount; i++)

 		{

 		CX509CertPolicyInfo* certPolicy = aPolicies.At(i);

 		for (TInt j = 0; j < chainCount; j++)

 			{

 			HBufC* chainPolicy = aAcceptablePolicies.At(j);

 			if (certPolicy->Id() == chainPolicy->Des())

 				{

 				return ETrue;

 				}

 			}

 		}

 	return EFalse;

 	}

 void TPKIXPolicyConstraint::UpdateConstraint(const TX509PolicyConstraint& aConstraint, TInt& aCountdown)

 	{

 	if (aConstraint.iRequired)

 		{

 		if (aConstraint.iCountdown < aCountdown)

 			aCountdown = aConstraint.iCountdown;

 		}

 	}

 void TPKIXPolicyConstraint::FinishPolicyCheckL()

 	{

 	if (iState.iUserConstrainedPolicies)

 		{

 		TBool passed = EFalse;

 		if (!(iState.iAnyAuthorityPolicy))

 			{//policy from user policies must be in authority policy set

 			if ((PolicyIsPresentL(*(iState.iAuthorityConstrainedPolicies), *(iState.iUserPolicies))))

 				{

 				passed = ETrue;

 				}

 			}		

 		if (!passed)

 			{

 			iResult.SetErrorAndLeaveL(ERequiredPolicyNotFound, iState.iPos);

 			}

 		}

 	}

 CArrayPtrFlat<CX509CertPolicyInfo>* TPKIXPolicyConstraint::IntersectionLC(

 									const CArrayPtrFlat<CX509CertPolicyInfo>& aFirst,

 									const CArrayPtrFlat<CX509CertPolicyInfo>& aSecond)

 	//constructs an array of certificate policy objects, 

 	//populating it with policies that occur in both of the array parameters

 	{

 	CArrayPtrFlat<CX509CertPolicyInfo>* inter = new(ELeave) CArrayPtrFlat<CX509CertPolicyInfo> (1);

 	TCleanupItem cleanupPolicies(CleanupPolicyInfoArray, inter);

 	CleanupStack::PushL(cleanupPolicies);

 	TInt count1 = aFirst.Count();

 	TInt count2 = aSecond.Count();

 	for (TInt i = 0; i < count1; i++)

 		{

 		CX509CertPolicyInfo* policy1 = aFirst.At(i);

 		for (TInt j = 0; j < count2; j++)

 			{

 			CX509CertPolicyInfo* policy2 = aSecond.At(j);

 			if (policy1->Id() == policy2->Id())

 				{

 				CX509CertPolicyInfo* info = CX509CertPolicyInfo::NewLC(*policy1);

 				inter->AppendL(info);

 				CleanupStack::Pop();

 				}

 			}

 		}

 	return inter;

 	}

 //name constraint

 //public functions

 TPKIXNameConstraint::TPKIXNameConstraint(	CPKIXValidationState& aState, 

 											CPKIXValidationResultBase& aResult)

 	:TPKIXConstraint(aState, aResult)

 	{

 	}

 void TPKIXNameConstraint::CheckNameConstraintsL(const CX509Certificate& aCert) 

 	{

 	//*do the subject name

 	if (NameIsPresentL(aCert.SubjectName(), *(iState.iExcludedDNSubtrees)))

 		{

 		iResult.SetErrorAndLeaveL(ENameIsExcluded, iState.iPos);

 		}

 	TInt pCount = iState.iPermittedDNSubtrees->Count();

 	if ((pCount > 0) && (!(NameIsPresentL(aCert.SubjectName(), *(iState.iPermittedDNSubtrees)))))

 		{

 		iResult.SetErrorAndLeaveL(ENameNotPermitted, iState.iPos);

 		}

 	//*do the alt name

 	const CX509CertExtension* ext = aCert.Extension(KSubjectAltName);

 	if (ext)

 		{

 		CX509AltNameExt* altNameExt = CX509AltNameExt::NewLC(ext->Data());

 		const CArrayPtrFlat<CX509GeneralName>& altName = altNameExt->AltName();

 		TInt count = altName.Count();

 		for (TInt i = 0; i < count; i++)

 			{

 			const CX509GeneralName* gN = altName.At(i);

 			switch (gN->Tag())

 				{

 				case EX509DirectoryName://X500DN

 					{

 					const CX500DistinguishedName* dN = CX500DistinguishedName::NewLC(gN->Data());

 					if (NameIsPresentL(*dN, *(iState.iExcludedDNSubtrees)))

 						{

 						iResult.SetErrorAndLeaveL(ENameIsExcluded, iState.iPos);

 						}

 					if ((pCount > 0) && (!(NameIsPresentL(*dN, *(iState.iPermittedDNSubtrees)))))

 						{

 						iResult.SetErrorAndLeaveL(ENameNotPermitted, iState.iPos);

 						}

 					CleanupStack::PopAndDestroy();

 					}			

 					break;

 				case EX509RFC822Name://IA5String

 					{

 					const CX509RFC822Name* name = CX509RFC822Name::NewLC(gN->Data());

 					if (NameIsPresent(*name, *(iState.iExcludedRFC822Subtrees)))

 						{

 						iResult.SetErrorAndLeaveL(ENameIsExcluded, iState.iPos);

 						}

 					if ((iState.iPermittedRFC822Subtrees->Count() > 0) && (!(NameIsPresent(*name, *(iState.iPermittedRFC822Subtrees)))))

 						{

 						iResult.SetErrorAndLeaveL(ENameNotPermitted, iState.iPos);

 						}

 					CleanupStack::PopAndDestroy();

 					}

 					break;

 				case EX509URI://IA5String

 					{

 					const CX509IPBasedURI* name = CX509IPBasedURI::NewLC(gN->Data());

 					const CX509DNSName& domain = name->Host();

 					if (NameIsPresent(domain, *(iState.iExcludedDNSNameSubtrees)))

 						{

 						iResult.SetErrorAndLeaveL(ENameIsExcluded, iState.iPos);

 						}

 					if ((iState.iPermittedDNSNameSubtrees->Count() > 0) && (!(NameIsPresent(domain, *(iState.iPermittedDNSNameSubtrees)))))

 						{

 						iResult.SetErrorAndLeaveL(ENameNotPermitted, iState.iPos);

 						}

 					CleanupStack::PopAndDestroy();

 					}

 					break;

 				case EX509DNSName://IA5String

 					{

 					const CX509DNSName* name = CX509DNSName::NewLC(gN->Data());

 					if (NameIsPresent(*name, *(iState.iExcludedDNSNameSubtrees)))

 						{

 						iResult.SetErrorAndLeaveL(ENameIsExcluded, iState.iPos);

 						}

 					if ((iState.iPermittedDNSNameSubtrees->Count() > 0) && (!(NameIsPresent(*name, *(iState.iPermittedDNSNameSubtrees)))))

 						{

 						iResult.SetErrorAndLeaveL(ENameNotPermitted, iState.iPos);

 						}

 					CleanupStack::PopAndDestroy();

 					}

 					break;

 				case EX509IPAddress://octet string

 					{

 					const CX509IPAddress* name = CX509IPAddress::NewLC(gN->Data());

 					if (NameIsPresent(*name, *(iState.iExcludedIPAddressSubtrees)))

 						{

 						iResult.SetErrorAndLeaveL(ENameIsExcluded, iState.iPos);

 						}

 					if ((iState.iPermittedIPAddressSubtrees->Count() > 0) && (!(NameIsPresent(*name, *(iState.iPermittedIPAddressSubtrees)))))

 						{

 						iResult.SetErrorAndLeaveL(ENameNotPermitted, iState.iPos);

 						}

 					CleanupStack::PopAndDestroy();

 					}

 					break;

 				}

 			}//end of for loop

 		//we've handled this now, so can remove it from the critical list

 		Remove(*(iState.iCriticalExts), KSubjectAltName);

 		CleanupStack::PopAndDestroy();//altNameExt

 		}//end of if(ext)

 	}

 void TPKIXNameConstraint::UpdateNameConstraintsL(const CX509Certificate& aCert)

 	{

 	const CX509CertExtension* ext = aCert.Extension(KNameConstraints);

 	if (ext)

 		{

 		CX509NameConstraintsExt* nameCons = CX509NameConstraintsExt::NewLC(ext->Data());

 		const CArrayPtrFlat<CX509GeneralSubtree>& excSubtrees = nameCons->ExcludedSubtrees();

 		TInt count = excSubtrees.Count();

 		for (TInt i = 0; i < count; i++)

 			{

 			const CX509GeneralSubtree* subtree = excSubtrees.At(i);

 			const CX509GeneralName& gN = subtree->Name();

 			switch (gN.Tag())

 				{

 				case EX509DirectoryName://X500DN

 					{

 					CX500DistinguishedName* name = CX500DistinguishedName::NewLC(gN.Data());

 					iState.iExcludedDNSubtrees->AppendL(name);

 					CleanupStack::Pop();

 					}			

 					break;

 				case EX509RFC822Name://IA5String

 					{

 					CX509RFC822Name* name = CX509RFC822Name::NewLC(gN.Data());

 					iState.iExcludedRFC822Subtrees->AppendL(name);

 					CleanupStack::Pop();

 					}

 					break;

 				case EX509URI://IA5String

 					{

 					CX509IPBasedURI* name = CX509IPBasedURI::NewLC(gN.Data());

 					CX509DNSName* domain = CX509DNSName::NewLC(name->Host());

 					iState.iExcludedDNSNameSubtrees->AppendL(domain);

 					CleanupStack::Pop();

 					CleanupStack::PopAndDestroy();

 					}

 					break;

 				case EX509DNSName://IA5String

 					{

 					CX509DNSName* name = CX509DNSName::NewLC(gN.Data());

 					iState.iExcludedDNSNameSubtrees->AppendL(name);

 					CleanupStack::Pop();

 					}

 					break;

 				case EX509IPAddress://octet string

 					{

 					CX509IPSubnetMask* name = CX509IPSubnetMask::NewLC(gN.Data());

 					iState.iExcludedIPAddressSubtrees->AppendL(name);

 					CleanupStack::Pop();

 					}	

 					break;

 				default:

 					{

 					User::Leave(KErrNotSupported);

 					}

 					break;

 				}

 			}//end of for loop

 		const CArrayPtrFlat<CX509GeneralSubtree>& perSubtrees = nameCons->PermittedSubtrees();

 		count = perSubtrees.Count();

 		for (TInt j = 0; j < count; j++)

 			{

 			const CX509GeneralSubtree* subtree = perSubtrees.At(j);

 			const CX509GeneralName& gN = subtree->Name();

 			switch (gN.Tag())

 				{

 				case EX509DirectoryName://X500DN

 					{

 					CX500DistinguishedName* name = CX500DistinguishedName::NewLC(gN.Data());

 					iState.iPermittedDNSubtrees->AppendL(name);

 					CleanupStack::Pop();

 					}			

 					break;

 				case EX509RFC822Name://IA5String

 					{

 					CX509RFC822Name* name = CX509RFC822Name::NewLC(gN.Data());

 					iState.iPermittedRFC822Subtrees->AppendL(name);

 					CleanupStack::Pop();

 					}

 					break;

 				case EX509URI://IA5String

 					{

 					CX509IPBasedURI* name = CX509IPBasedURI::NewLC(gN.Data());

 					CX509DNSName* domain = CX509DNSName::NewLC(name->Host());

 					iState.iPermittedDNSNameSubtrees->AppendL(domain);

 					CleanupStack::Pop();

 					CleanupStack::PopAndDestroy();

 					}

 					break;

 				case EX509DNSName://IA5String

 					{

 					CX509DNSName* name = CX509DNSName::NewLC(gN.Data());

 					iState.iPermittedDNSNameSubtrees->AppendL(name);

 					CleanupStack::Pop();

 					}

 					break;

 				case EX509IPAddress://octet string

 					{

 					CX509IPSubnetMask* name = CX509IPSubnetMask::NewLC(gN.Data());

 					iState.iPermittedIPAddressSubtrees->AppendL(name);

 					CleanupStack::Pop();

 					}

 					break;

 				default:

 					{

 					User::Leave(KErrNotSupported);

 					}

 					break;

 				}

 			}//end of for loop

 		CleanupStack::PopAndDestroy();//nameConsExt

 		//we've handled this now, so can remove it from the critical list

 		Remove(*(iState.iCriticalExts), KNameConstraints);

 		}//end of if(ext)

 	}

 //private functions

 TBool TPKIXNameConstraint::NameIsPresentL(	const CX500DistinguishedName& aSubject,

 											const CArrayPtrFlat<CX500DistinguishedName>& aSubtrees)

 	{

 	TInt count = aSubtrees.Count();

 	for (TInt i = 0; i < count; i++)

 		{

 		const CX500DistinguishedName* excluded = aSubtrees.At(i);

 		if (aSubject.IsWithinSubtreeL(*excluded))

 			{

 			return ETrue;

 			}

 		}

 	return EFalse;

 	}

 TBool TPKIXNameConstraint::NameIsPresent(	const CX509DomainName& aSubject,

 											const CArrayPtrFlat<CX509DomainName>& aSubtrees)

 	{

 	TInt count = aSubtrees.Count();

 	for (TInt i = 0; i < count; i++)

 		{

 		const CX509DomainName* excluded = aSubtrees.At(i);

 		if (aSubject.IsWithinSubtree(*excluded))

 			{

 			return ETrue;

 			}

 		}

 	return EFalse;

 	}	

 TBool TPKIXNameConstraint::NameIsPresent(	const CX509IPAddress& aSubject,

 											const CArrayPtrFlat<CX509IPSubnetMask>& aSubtrees)

 	{

 	TInt count = aSubtrees.Count();

 	for (TInt i = 0; i < count; i++)

 		{

 		const CX509IPSubnetMask* excluded = aSubtrees.At(i);

 		if (aSubject.IsWithinSubtree(*excluded))

 			{

 			return ETrue;

 			}

 		}

 	return EFalse;

 	}

 //basic constraint

 TPKIXBasicConstraint::TPKIXBasicConstraint(	CPKIXValidationState& aState, 

 											CPKIXValidationResultBase& aResult)

 	:TPKIXConstraint(aState, aResult)

 	{

 	}

 void TPKIXBasicConstraint::CheckCertSubjectTypeL(const CX509Certificate& aCert)

 	{

 	TBool markedAsCA = EFalse;

 	TBool actsAsCA = iState.iPos > 0;

 	const CX509CertExtension* ext = aCert.Extension(KBasicConstraints);

 	if (ext)

 		{

 		CX509BasicConstraintsExt* basic = CX509BasicConstraintsExt::NewLC(ext->Data());

 		markedAsCA = basic->IsCA();

 		CleanupStack::PopAndDestroy();

 		}

 	if (actsAsCA && (!markedAsCA))

 		{

 		iResult.SetErrorAndLeaveL(ENotCACert, iState.iPos);

 		}

 	}

 void TPKIXBasicConstraint::UpdatePathLengthConstraintsL(const CX509Certificate& aCert)

 	{

 	const CX509CertExtension* ext = aCert.Extension(KBasicConstraints);

 	if (ext)

 		{

 		CX509BasicConstraintsExt* basic = CX509BasicConstraintsExt::NewLC(ext->Data());

 		TInt pathLength = basic->MaxChainLength();

 		if (pathLength < 0)

 			{

 			iResult.SetErrorAndLeaveL(ENegativePathLengthSpecified, iState.iPos);

 			}

 		if (iState.iPos > pathLength)

 			{

 			iState.iMaxPathLength = pathLength + 1;

 			}

 		Remove(*(iState.iCriticalExts), KBasicConstraints);

 		CleanupStack::PopAndDestroy();//basic

 		}

 	}

 //key usage constraint

 TPKIXKeyUsageConstraint::TPKIXKeyUsageConstraint(	CPKIXValidationState& aState, 

 											CPKIXValidationResultBase& aResult)

 	:TPKIXConstraint(aState, aResult)

 	{

 	}

 void TPKIXKeyUsageConstraint::CheckKeyUsageL(const CX509Certificate& aCert)

 	{

 	//if key usage is critical and this is a CA cert, the keyCertSign bit must be set

 	const CX509CertExtension* ext = aCert.Extension(KKeyUsage);

 	if (ext)

 			{

 			CX509KeyUsageExt* keyUsage = CX509KeyUsageExt::NewLC(ext->Data());

 			if ( (iState.iPos > 0) && (!(keyUsage->IsSet(EX509KeyCertSign))))

 				{

 				iResult.SetErrorAndLeaveL(EBadKeyUsage, iState.iPos);

 				}

 			CleanupStack::PopAndDestroy();

 			//we've processed this critical ext, so remove it

 			Remove(*(iState.iCriticalExts), KKeyUsage);

 			}

 	}