/*

* Copyright (c) 2004 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:    Provides a class for AES CM 128 key derivation

*

*/

#include "srtpkeyderivation_aescm128.h"

#include "srtpaesctrcrypto.h"

#include "srtpdef.h"

#include "srtputils.h"

// ---------------------------------------------------------------------------

// CSRTPEncryptionAESCM128::NewL

// ---------------------------------------------------------------------------

//

CSRTPKeyDerivation_AESCM128* CSRTPKeyDerivation_AESCM128::NewL()

    {

    CSRTPKeyDerivation_AESCM128* self = CSRTPKeyDerivation_AESCM128::NewLC();

    CleanupStack::Pop(self);

    return self;    

    }

// ---------------------------------------------------------------------------

// CSRTPKeyDerivation_AESCM128::NewLC

// ---------------------------------------------------------------------------

//

CSRTPKeyDerivation_AESCM128* CSRTPKeyDerivation_AESCM128::NewLC()

    {

    CSRTPKeyDerivation_AESCM128* self = new( ELeave ) CSRTPKeyDerivation_AESCM128();

    CleanupStack::PushL( self );

    self->ConstructL();

    return self;

    }

// ---------------------------------------------------------------------------

// CSRTPKeyDerivation_AESCM128::PRF_128BitL

// ---------------------------------------------------------------------------

//

HBufC8* CSRTPKeyDerivation_AESCM128::PRF_128BitL(TUint aBitLength, 

                                              const TDesC8& aKey, 

                                              const TDesC8& aIV)

    {    

    HBufC8* paddedIV = NULL;

    HBufC8* keystream = NULL;

    TBuf8<1> padChar;

    // if the IV value is shorter than the AES block size (128 bits, 16 octets),

    // --> do the padding       

    if (aIV.Length() < KAESCM128BlockSizeInBytes)

        {

        paddedIV = HBufC8::NewMaxL(KAESCM128BlockSizeInBytes);

        CleanupStack::PushL(paddedIV);

        TUint8* ptr = const_cast<TUint8*>(paddedIV->Des().Ptr());

        Mem::FillZ( ptr, KAESCM128BlockSizeInBytes);        

        Mem::Copy( ptr, aIV.Ptr(), aIV.Length() );                    

        }

     if (!paddedIV)

        {

        // get the AES keystream with the original IV value       

        keystream = iEncryptor->KeystreamL(aBitLength, aKey, aIV);            

        }

     else

        {        

        // get the AES keystream with the padded IV value       

        keystream = iEncryptor->KeystreamL(aBitLength, aKey, *paddedIV);            

        }

    if (paddedIV)

        {

        CleanupStack::Pop(paddedIV);

        delete paddedIV; paddedIV=NULL;

        } 

    return keystream;

    }

// ---------------------------------------------------------------------------

// CSRTPKeyDerivation_AESCM128::ConstructL

// ---------------------------------------------------------------------------

//

void CSRTPKeyDerivation_AESCM128::ConstructL()

    {    

    // Create AES-CTR Wrapper

    iEncryptor = CSrtpAESCTRCrypto::NewL();        

    }

// ---------------------------------------------------------------------------

// CSRTPKeyDerivation_AESCM128::~CSRTPKeyDerivation_AESCM128

// ---------------------------------------------------------------------------

//

CSRTPKeyDerivation_AESCM128::~CSRTPKeyDerivation_AESCM128()

    {    

    // delete AES-CTR Wrapper

    delete iEncryptor;

    }

// ---------------------------------------------------------------------------

// CSRTPKeyDerivation_AESCM128::CSRTPKeyDerivation_AESCM128

// ---------------------------------------------------------------------------

//

CSRTPKeyDerivation_AESCM128::CSRTPKeyDerivation_AESCM128()

    {    

    }