// 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 "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:

//

/**

 @file dhparamreader.cpp

 @internalTechnology

*/

#include "dhparamreader.h"

#include <f32file.h>

#include <asn1dec.h>

void CDHParamReader::DecodeDERL(const TDesC& aDerFile,

	RInteger& aPrimeOut, RInteger& aGeneratorOut)

	{

	RFs fs;

	User::LeaveIfError(fs.Connect());

	CleanupClosePushL(fs);

	RFile file;

	User::LeaveIfError(file.Open(fs, aDerFile, EFileRead));

	CleanupClosePushL(file);

	TInt fileSize(0);

	User::LeaveIfError(file.Size(fileSize));

	HBufC8* derData = HBufC8::NewLC(fileSize);

	TPtr8 derPtr = derData->Des();

	User::LeaveIfError(file.Read(derPtr));

	// we know this should just be an ASN.1 sequence, consisting of two integers....

	TASN1DecGeneric genDec(*derData);

	genDec.InitL();

	if (genDec.Tag() != EASN1Sequence)

		{

		// not a sequence...

		User::Leave(KErrNotSupported);

		}

	TASN1DecSequence seq;

	CArrayPtrFlat<TASN1DecGeneric>* ints = seq.DecodeDERLC(genDec);

	// validate the sequence data

	if (ints->Count() != 2 || 

		ints->At(0)->Tag() != EASN1Integer ||

		ints->At(1)->Tag() != EASN1Integer)

		{

		// This isn't a DH parameter file we can recognise...

		User::Leave(KErrNotSupported);

		}

	// Read the integers from the sequence....

	TASN1DecInteger decInt;

	aPrimeOut = decInt.DecodeDERLongL(*ints->At(0));

	aGeneratorOut = decInt.DecodeDERLongL(*ints->At(1));

	CleanupStack::PopAndDestroy(4, &fs); // file, derData, ints

	}