/*

* Copyright (c) 2005-2009 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 "pkcs7encrypteddataobject.h"

/** The last character in the PKCS7 EncryptedData OID */

const TInt KPkcs7EncryptedData = 6;

EXPORT_C CPKCS7EncryptedDataObject* CPKCS7EncryptedDataObject::NewL(const CPKCS7ContentInfo& aContentInfo)

	{

	CPKCS7EncryptedDataObject* self = new (ELeave) CPKCS7EncryptedDataObject();

	CleanupStack::PushL(self);

	self->ConstructL(aContentInfo);

	CleanupStack::Pop(self);

	return self;	

	}

CPKCS7EncryptedDataObject::CPKCS7EncryptedDataObject(void)

	{

	}

CPKCS7EncryptedDataObject::~CPKCS7EncryptedDataObject()

	{

	delete iEncryptParams;

	}

EXPORT_C TInt CPKCS7EncryptedDataObject::Version() const

	{

	return iVersion;

	}

EXPORT_C CPKCS7EncryptedDataObject::TContentType CPKCS7EncryptedDataObject::ContentType() const

	{

	return iContentType;

	}

EXPORT_C const TDesC8& CPKCS7EncryptedDataObject::EncryptedContentInfoData() const

	{

	return iEncryptedContent;

	}	

EXPORT_C const CPBEncryptParms& CPKCS7EncryptedDataObject::EncryptParams() const

	{

	return *iEncryptParams;

	}

CPBEncryptParms* CPKCS7EncryptedDataObject::DecodeContentEncryptionAlgorithmL(const TDesC8& aBinaryData) const

	{

	TASN1DecGeneric seqGen(aBinaryData);

	seqGen.InitL();

	if (seqGen.Tag() != EASN1Sequence || seqGen.Class() != EUniversal)

		{

		User::Leave(KErrArgument);

		}

    TPtrC8 theContent(seqGen.Encoding());

    CPBEncryptParms* encryptParams =  TASN1DecPKCS5::DecodeDERL(theContent);

    return encryptParams;

	}	

EXPORT_C HBufC8* CPKCS7EncryptedDataObject::DecryptDataL(const TDesC& aPassword) const

	{

	CPBEncryptElement* encryptElement;

    HBufC8* pkcs12Pwd = PKCS12KDF::GeneratePasswordLC(aPassword);

    if(iEncryptParams->Kdf() == CPBEncryptParms::EKdfPkcs12)

		{

	 	TPtrC8 iv = iEncryptParams->IV();

	    HBufC8* ivValue = HBufC8::NewMaxLC(iv.Length());

	    TPtr8 encryptKeyBuf = ivValue->Des();

	 	switch(iEncryptParams->Cipher())	

			{

	 		case ECipherARC4_128:

	 		case ECipherARC4_40:

	 			{

	 	    	//derive only key it is unnecessary to derive an IV for RC4

	 	    	break;

	 			}

			case ECipher3DES_CBC:

			case ECipher2Key3DES_CBC:

			case ECipherRC2_CBC_128_16:	 

			case ECipherRC2_CBC_40_5:	

				{

				PKCS12KDF::DeriveKeyL(encryptKeyBuf, PKCS12KDF::EIDByteIV, *pkcs12Pwd, iEncryptParams->Salt(), iEncryptParams->Iterations());

				iEncryptParams->SetIV(encryptKeyBuf);

		    	break;

				}

			default:

				{

		    	User::Leave(KErrNotSupported);

		    	break;

				}

	 		}

	 	CleanupStack::PopAndDestroy(ivValue);

		// Create the decryptor	

		encryptElement = CPBEncryptElement::NewLC(*pkcs12Pwd, *iEncryptParams);

		}

	else

		{

		TPBPassword password(aPassword);

		// Create the decryptor	

		encryptElement = CPBEncryptElement::NewLC(password.Password(), *iEncryptParams);	

		}

	CPBDecryptor* decryptor = encryptElement->NewDecryptLC();

	TPtrC8 encryptedKey(iEncryptedContent);

	TUint encryptLength = encryptedKey.Length();

	TUint maxDecryptLength = decryptor->MaxOutputLength(encryptLength);

	if ( maxDecryptLength <= 0 )

		{

		User::Leave(KErrGeneral);		

		}

	HBufC8* decryptedContent = HBufC8::NewLC(maxDecryptLength);

	TPtr8 dcDes(decryptedContent->Des());

	decryptor->Process(encryptedKey, dcDes);

	CleanupStack::Pop(decryptedContent);

	CleanupStack::PopAndDestroy(3, pkcs12Pwd); // pkcs12Pwd, encryptElement, decryptor

   	return decryptedContent;

   	}

 void CPKCS7EncryptedDataObject::ConstructL(const CPKCS7ContentInfo& aContentInfo)

	{

	if(aContentInfo.ContentType() != KPkcs7EncryptedData)

		{

		User::Leave(KErrArgument);

		}

	// EncryptedData SEQUENCE

	TASN1DecGeneric decGen(aContentInfo.ContentData());

	decGen.InitL();

	if(decGen.Tag() != EASN1Sequence || decGen.Class() != EUniversal)

		{

	    User::Leave(KErrArgument);

		}

    TASN1DecSequence seq1;

    CArrayPtrFlat<TASN1DecGeneric>* EncryptedDataContents = seq1.DecodeDERLC(decGen);       					

	// Both version and encryptedContentInfo should be present

	if (EncryptedDataContents->Count() != 2)

		{

		User::Leave(KErrArgument);

		}

	// VERSION

	// version is the syntax version number. It shall be 0 for this version of the standard

	const TASN1DecGeneric* EncryptedDataContentsAt0 = EncryptedDataContents->At(0);

	if(EncryptedDataContentsAt0->Tag() != EASN1Integer || EncryptedDataContentsAt0->Class() != EUniversal)

		{

		User::Leave(KErrArgument);

		}

	TASN1DecInteger intDecoder;

	iVersion = intDecoder.DecodeDERShortL(*EncryptedDataContentsAt0);

	if (iVersion != 0)

		{

	    User::Leave(KErrArgument);		

	    }

    // ENCRYPTED CONTENT INFO a SEQUENCE

    const TASN1DecGeneric* EncryptedDataContentsAt1 = EncryptedDataContents->At(1);

	if (EncryptedDataContentsAt1->Tag() != EASN1Sequence || EncryptedDataContentsAt1->Class() != EUniversal)

		{

	    User::Leave(KErrArgument);

	    }		               

	TASN1DecSequence seq2;

    CArrayPtrFlat<TASN1DecGeneric>* EncryptedContentInfo = seq2.DecodeDERLC(*EncryptedDataContentsAt1);       

    // CONTENT TYPE IDENTIFIED BY AN OBJECT IDENTIFIER

	// Gets the oid

	TASN1DecObjectIdentifier ContentTypeoidDec;

	HBufC* contentType = ContentTypeoidDec.DecodeDERL(*EncryptedContentInfo->At(0));

	if(contentType->Compare(KPkcs7DataOID()) == 0)

		{

		iContentType = EPkcs7Data;

		}

	else

		{

		User::Leave(KErrNotSupported);

		}

	delete contentType;	        

	// CONTENT ENCRYPTION ALGORITHM

	// Get the Cipher used and the encoded params in it

    iEncryptParams = DecodeContentEncryptionAlgorithmL(EncryptedContentInfo->At(1)->Encoding());

    // ENCRYPTED CONTENT

	// This is an OPTIONAL field

	TInt encryptedContentInfoCount = EncryptedContentInfo->Count();

	if(encryptedContentInfoCount == 3)

		{

		TASN1DecGeneric decOctetString(*EncryptedContentInfo->At(2));

		decOctetString.InitL();

	    iEncryptedContent.Set(decOctetString.GetContentDER());

	   	}

	else if(encryptedContentInfoCount > 3 || encryptedContentInfoCount < 2)

	    {

	    User::Leave(KErrArgument);

	    }

	else if(encryptedContentInfoCount == 2)

		{

		iEncryptedContent.Set(KNullDesC8());

		}

	CleanupStack::PopAndDestroy(2, EncryptedDataContents); //EncryptedDataContents, EncryptedContentInfo    	

	}