Turtles All The Way Down: Research Challenges in User-Based Attestation ∗
Jonathan M. McCune, Adrian Perrig, Arvind Seshadri, Leendert van Doorn · 2007
A scientist once gave a public lecture describing how the Earth orbits around the sun and how the sun, in turn, orbits around the center of a collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: What you have told us is rubbish. The world is really a at plate supported on the back of a giant tortoise. The scientist gave a superior smile before replying, What is the tortoise standing on? You're very clever, young man, very clever, said the old lady, but it's turtles all the way down! Current trusted computing technologies allow comput-ing devices to verify each other, but in a networked world, there is no reason to trust one computing device any more than another. Treating these devices as turtles, the user who seeks a trustworthy system from which to verify oth-ers quickly realizes that it’s turtles all the way down because of the endless loop of trust dependencies. We need to provide the user with one initial turtle (the iTur-tle) which is axiomatically trustworthy, thereby breaking the dependency loop. In this paper, we present some of the research challenges involved in designing and using such an iTurtle. 1