Coin flipping of any constant bias implies one-way functions

Abstract

We show that the existence of a coin-flipping protocol safe against any non-trivial constant bias (e.g., .499) implies the existence of one-way functions. This improves upon a recent result of Haitner and Omri [FOCS '11], who proved this implication for protocols with bias [EQUATION] -- o(1) ≈ .207. Unlike the result of Haitner and Omri, our result also holds for weak coin-flipping protocols.