Abstract. A physically unclonable function (PUF) is a multiple-input, multipleoutput, large entropy physical system that is unreproducible due to its structural complexity. A public physically unclonable function (PPUF) is a PUF that is created so that its simulation is feasible but requires very large time even when ample computational resources are available. Using PPUFs, we have developed conceptually new secret key exchange and public key protocols that are resilient against physical and side channel attacks and do not employ unproven mathematical conjectures. Judicious use of PPUF hardware sharing, parallelism, and provably correct partial simulation enables 1016 advantage of communicating parties over an attacker, requiring over 500 of years of computation even if the attacker uses all global computation resources.