24-Hour Relativistic Bit Commitment

• Main Authors: Verbanis, Ephanielle, Martin, Anthony, Houlmann, Raphaël, Boso, Gianluca, Bussières, Félix, Zbinden, Hugo
• Format: Journal Article
• Language: English
• Published: 24-05-2016
• Subjects: Physics - Quantum Physics
• DOI: 10.48550/arxiv.1605.07442

Phys. Rev. Lett. 117, 140506 (2016) Bit commitment is a fundamental cryptographic primitive in which a party
wishes to commit a secret bit to another party. Perfect security between
mistrustful parties is unfortunately impossible to achieve through the
asynchronous exchange of classical and quantum messages. Perfect security can
nonetheless be achieved if each party splits into two agents exchanging
classical information at times and locations satisfying strict relativistic
constraints. A relativistic multi-round protocol to achieve this was previously
proposed and used to implement a 2~millisecond commitment time. Much longer
durations were initially thought to be insecure, but recent theoretical
progress showed that this is not so. In this letter, we report on the
implementation of a 24-hour bit commitment based on timed high-speed optical
communication and fast data processing only, with all agents located within the
city of Geneva. This duration is more than six orders of magnitude longer than
before, and we argue that it could be extended to one year and allow much more
flexibility on the locations of the agents. Our implementation offers a
practical and viable solution for use in applications such as digital
signatures, secure voting and honesty-preserving auctions.