Unconditionally secure relativistic multi-party biased coin flipping and die rolling

TL;DR

This paper presents the first practical, unconditionally secure multi-party relativistic protocols for biased die rolling, extending secure coin flipping to multiple parties and outcomes without quantum communication.

Contribution

It introduces unconditionally secure relativistic multi-party biased die rolling protocols, generalizing previous two-party coin flipping to multiple parties and outcomes, with practical implementation.

Findings

Protocols are unconditionally secure and extend to multiple parties and outcomes.

No quantum communication required, practical with current technology.

First multi-party relativistic cryptographic protocols known.

Abstract

We introduce relativistic multi-party biased die rolling protocols, generalizing coin flipping to $M \geq 2$ parties and to $N \geq 2$ outcomes for any chosen outcome biases, and show them unconditionally secure. Our results prove that the most general random secure multi-party computation, where all parties receive the output and there is no secret input by any party, can be implemented with unconditional security. Our protocols extend Kent's [A. Kent, Phys. Rev. Lett. 83, 5382 (1999)] two-party unbiased coin flipping protocol, do not require any quantum communication, are practical to implement with current technology, and to our knowledge are the first multi-party relativistic cryptographic protocols.