/*

* Copyright (c) 2007 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:  AES encryption utility for drm engine use

*

*/

// INCLUDE FILES

#include <e32std.h>

#include <symmetric.h>

#include <rijndael.h>

#include "drmaescrypto.h"

// ============================ MEMBER FUNCTIONS ===============================

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

// DrmAesCrypto::DrmAesEncryptL

// Encrypt data using a given key and insert initial vector on beginning

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

//

EXPORT_C HBufC8* DrmAesCrypto::DrmAesEncryptL(

    const TDesC8& aKey,

    const TDesC8& aIV,

    const TBool aAddPadding,

    const TDesC8& aData )

    {

    HBufC8* retBuf( NULL );

    CModeCBCEncryptor* cbc( NULL );

    TInt lastBlockStart( 0 );

    TPtr8 data( NULL, 0, 0 );

    if( aIV.Length() != KDCFKeySize || aKey.Length() != KDCFKeySize )

        {

        User::Leave( KErrArgument );

        }

    cbc = CModeCBCEncryptor::NewL( CAESEncryptor::NewLC( aKey ), aIV );

    CleanupStack::Pop(); // CAESEncryptor, owned by cbc.

    CleanupStack::PushL( cbc );

    retBuf = HBufC8::NewLC( aData.Size() + aIV.Size() + KDCFKeySize );

    data.Set( retBuf->Des() );

    data.Copy( aIV );

    data.Append( aData );

    lastBlockStart = data.Length() - ( data.Length() % KDCFKeySize );

    // Loop through the data, excluding aIV

    for ( TInt i = KDCFKeySize; i  < lastBlockStart; i+= KDCFKeySize )

        {

        data.Set( retBuf->Des().MidTPtr( i, KDCFKeySize ) );

        cbc->Transform( data );

        }

    if ( aAddPadding )

        {

        TInt dataLength = retBuf->Length();

        TUint8 padding( static_cast< TUint8 >

            ( lastBlockStart + KDCFKeySize - dataLength ) );

        __ASSERT_DEBUG( lastBlockStart + KDCFKeySize - dataLength <= KDCFKeySize,

            User::Invariant() );

        retBuf->Des().SetLength( lastBlockStart + KDCFKeySize );

        for ( TInt i = dataLength; i < retBuf->Length(); ++i )

            {

            retBuf->Des()[ i ] = padding;

            }

        data.Set( retBuf->Des().MidTPtr( lastBlockStart, KDCFKeySize ) );

        cbc->Transform( data );

        }

    CleanupStack::Pop( retBuf );

    CleanupStack::PopAndDestroy( cbc );

    return retBuf;

    }

//  End of File