A method and system as disclosed for use in a virus-free certificate proxy, of retrieving from one or a plurality of virus-free certificate authorities a virus-free certificate certifying that a file is virus-free. The thermally curable resin composition for a protective film of the present invention includes an alkoxy group-containing silane-modified epoxy resin as an essential component to have excellent film strength and adhesive strength, and thus may be effectively used in a protective film of a color filter for a liquid crystal display device. The outer film layer has an inner surface adjacent to and bonded to the plastic layer and an outer surface opposed to the inner surface.