Information-theoretic security without an honest majority

TL;DR

This paper introduces six multiparty protocols that achieve information-theoretic security without requiring an honest majority, tolerating any number of corrupt participants under specific communication assumptions.

Contribution

The paper presents new multiparty protocols for various functionalities that operate securely without relying on computational assumptions or honest majority.

Findings

Protocols tolerate any number of corrupt participants.

Achieve functionalities not possible without honest majority.

Operate under pairwise authentic channels and broadcast channels.

Abstract

We present six multiparty protocols with information-theoretic security that tolerate an arbitrary number of corrupt participants. All protocols assume pairwise authentic private channels and a broadcast channel (in a single case, we require a simultaneous broadcast channel). We give protocols for veto, vote, anonymous bit transmission, collision detection, notification and anonymous message transmission. Not assuming an honest majority, in most cases, a single corrupt participant can make the protocol abort. All protocols achieve functionality never obtained before without the use of either computational assumptions or of an honest majority.