Optimal quantum strong coin flipping
Loading...
Date
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Description
Coin flipping is a fundamental cryptographic primitive that enables two distrustful and far apart parties to create a uniformly random bit [Blu81]. Quantum information allows for protocols in the information theoretic setting where no dishonest party can perfectly cheat. The previously best-known quantum protocol by Ambainis achieved a cheating probability of at most 3/4 [Amb01]. On the other hand, Kitaev showed that no quantum protocol can have cheating probability less than $1/\sqrt{2}$ [Kit03]. Closing this gap has been one of the important open questions in quantum cryptography.
In this paper, we resolve this question by presenting a quantum strong coin flipping protocol with cheating probability arbitrarily close to $1/\sqrt{2}$. More precisely, we show how to use any weak coin flipping protocol with cheating probability $1/2+ε$ in order to achieve a strong coin flipping protocol with cheating probability $1/\sqrt{2}+O(ε)$. The optimal quantum strong coin flipping protocol follows from our construction and the optimal quantum weak coin flipping protocol described by Mochon [Moc07].
12 pages
12 pages