How can I compare a data binary with GridFs in MongoDb?

I am using C # and MongoDB as the database engine. In my application I keep the User's Footprint used the following lines in C #.

         var id3 = ObjectId.Empty;
            using (var file = File.OpenRead(rutaArchivo))
            {
                id3 = gridFs.AddFile(file, ruta);//Obtengo el id de mi  griffile mongo 
                 //y lo guarda en mi base de datos
            }

Save it as follows in my Fs.Files:

Likewise for my Fs.Chunks

What I can not do so far is compare the user's footprint with each one saved in my database.