Virtual Proofs of Reality

In this paper, we discuss the question how physical statements can be proven remotely over digital communication channels without using classical secret keys, and without assuming tamper-resistant and trusted measurement hardware in the location of the prover. Examples for the considered physical statements are: (i) “the temperature of a certain object is X◦C”, (ii) “two certain objects are positioned at distance X”, or (iii) “a certain object has been irreversibly altered or destroyed”. In lack of an established name, we would like to call the corresponding security protocols ”virtual proofs of reality” (VPs). While a host of variants seems conceivable, this paper focuses on VPs in which the verifier has handed over one or more specific physical objects Oi to the prover at some point prior to the VP. These “witness objects” assist the prover during the proof, but shall not contain classical digital keys nor be assumed tamper-resistant in the classical sense. The prover is allowed to open, inspect and alter these objects in our adversarial model, only being limited by current technology, while he shall still be unable to prove false claims to the verifier. In order to illustrate our concept, we give example protocols built on temperature sensitive integrated circuits, disordered optical scattering media, and quantum systems. These protocols prove the temperature, destruction/modification, or relative position of witness objects in the prover’s location. Full experimental realizations of these schemes are beyond the scope of this paper. But the protocols utilize established technologies from the areas of physical unclonable functions and quantum cryptography, and hence appear plausible also without such proof. Finally, we also discuss potential advancements of our method in theory, for example “public virtual proofs” that function without exchanging witness objects Oi between the verifier and the prover. Our work touches upon and partly extends several established cryptographic and security concepts, including physical unclonable functions, quantum cryptography, and interactive proof systems. Keywords-Virtual Proofs of Reality (VPs), Physical Unclonable Functions (PUFs), Interactive Proof Systems, Quantum Cryptography, Physical Cryptography