No Superluminal Signaling Implies Unconditionally Secure Bit Commitment

TL;DR

This paper presents a simple, practical, and unconditionally secure bit commitment protocol based solely on classical communication and the no superluminal signaling principle, eliminating the need for quantum mechanics.

Contribution

It introduces the first classical, unconditionally secure bit commitment scheme relying only on no superluminal signaling, simplifying implementation and theoretical understanding.

Findings

Scheme is based on classical communication and NSS.

Achieves unconditional security without quantum mechanics.

Practical implementation with existing telecom technologies.

Abstract

Bit commitment (BC) is an important cryptographic primitive for an agent to convince a mutually mistrustful party that she has already made a binding choice of 0 or 1 but only to reveal her choice at a later time. Ideally, a BC protocol should be simple, reliable, easy to implement using existing technologies, and most importantly unconditionally secure in the sense that its security is based on an information-theoretic proof rather than computational complexity assumption or the existence of a trustworthy arbitrator. Here we report such a provably secure scheme involving only one-way classical communications whose unconditional security is based on no superluminal signaling (NSS). Our scheme is inspired by the earlier works by Kent, who proposed two impractical relativistic protocols whose unconditional securities are yet to be established as well as several provably unconditionally secure protocols which rely on both quantum mechanics and NSS. Our scheme is conceptually simple and shows for the first time that quantum communication is not needed to achieve unconditional security for BC. Moreover, with purely classical communications, our scheme is practical and easy to implement with existing telecom technologies. This completes the cycle of study of unconditionally secure bit commitment based on known physical laws.