Ryan Amos will present General Exam Presentation May 21, 2018 at 1:00 pm in CS301. Title: Verifiable Random Beacons Abstract: Random beacons sources of open, public randomness, and play a critical role in many protocols. Their uses range from proofs of earliest possible creation date to secure multiparty computation to lottery systems. Existing sources of public randomness, including various random beacons, are subject to single points of failure, such that an opportunistic adversary might be able to meaningfully affect the outcome. We develop a random beacon that always requires compromising more than one party to meaningfully affect the outcome. In order to further discourage dishonest behavior, every critical step of our protocol is third-party auditable and backed by economic incentives that make honest behavior more profitable than dishonest behavior. Our method uses a variant of a verifiable random function (VRF) to "scramble" a public input in an unpredictable, thresholded manner, making it difficult for anyone one party to predict how changes to the public input affect the output, or to affect or suppress the output. The proofs of the VRFs are verified by smart contracts to provide monetary reward or penalty, as appropriate, to protocol participants, ensuring honesty is the best fiscal policy. Barbara A. Mooring Interim Graduate Coordinator Computer Science Department Princeton University