The only markings I have heard of that link it to Khufu are the ones found by the French guy and they appear to be the subject of controversy anyway. Laying 2,000,000 blocks in 20 years is one hell of an effort. Particularly when you consider how sophisticated it is.They have a fair idea just based off the markings on the stone blocks themselves, where they came from, how they were hewn & how they were transported.