Android, DocumentProvider, ParcelFileDescriptor, override getStream()

Question

I am writing my DocuemtnProvider for Android OS. My application works with encrypted files. And i should return ParcelFileDescriptor on openDocument method.

I don't want store temp decrypted file. I Just want to override function like getStream() to return CipherInputStream.

Can anyone help me ?

Here is some code:

public static ParcelFileDescriptor prepareFileDescriptor(FileEntry entryForOpening, String mode, Handler handler) throws IOException {
    int parsedMode = ParcelFileDescriptor.parseMode(mode);
    File realFile = FileCache.get().fileFromRelCachePath(entryForOpening);
    //TODO decrypt to temp set it into listener
    FileDescriptorListener listener = new FileDescriptorListener(entryForOpening, parsedMode);
    return ParcelFileDescriptor.open(realFile, parsedMode, handler, listener);
}