Claude Crépeau, School of Computer Science, McGill University will deliver “Experimental Relativistic Zero-Knowledge Proofs” at 11 a.m. Aug. 9 in room 113 at the Stuart Building.

Protecting secrets is a key challenge in our contemporary
information-based era. In common situations, however, revealing
secrets appears unavoidable, for instance, when identifying oneself in
a bank to retrieve money. In turn, this may have highly undesirable
consequences in the unlikely, yet not unrealistic, case where the
bank’s security gets compromised. This naturally raises the question
of whether disclosing secrets is fundamentally necessary for
identifying oneself, or more generally for proving a statement to be
correct. Developments in computer science provide an elegant solution
via the concept of zero-knowledge proofs: a prover can convince a
verifier of the validity of a certain statement without facilitating
the elaboration of a proof at all. In this work, we report the
experimental realisation of such a zero-knowledge protocol involving
two separated verifier-prover pairs. Security is enforced via the
physical principle of special relativity, and no computational
assumption (such as the existence of one-way functions) is required.
Our implementation exclusively relies on off-the-shelf equipment and
works at both short (60m) and long distances (>400m) in about one
second. This demonstrates the practical potential of multi-prover
zero-knowledge protocols, promising for identification tasks.

Joint work with Pouriya Alikhani, Nicolas Brunner, Sébastien Designolle,

Raphaël Houlmann, Weixu Shi, Nan Yang, and Hugo Zbinden
in Nature.