Unconditionally secure bit commitment by causally independent encryptions

TL;DR

This paper introduces a classical relativistic bit commitment protocol that guarantees unconditional security against classical and quantum attacks by leveraging causally independent encryptions and the finite speed of light.

Contribution

It presents a novel classical protocol using relativistic constraints that is unconditionally secure and practically implementable with current technology.

Findings

Protocol is unconditionally secure against classical and quantum attacks.

Commitment remains concealed for a duration proportional to distance divided by twice the speed of light.

Requires only classical communication and limited resources.

Abstract

We propose a new classical bit commitment protocol using the relativistic constraint that signals cannot travel faster than the speed of light $c$. This protocol is unconditionally secure against both classical or quantum attacks. The sender (Alice) and the receiver (Bob) each controls two secure stations separated by a large distance $d$, and they communicate by exchanging classical information only. Alice commits by sending from her stations two causally independent encrypted messages to the neighboring Bob's stations, after that the protocol is out of her control and she plays no role in the unveiling phase. The commitment remains concealed for a period of $\Delta t=d/2c$. This protocol requires only limited communication resources and is readily implementable with current technologies.