Paper 2019/853

A critique of game-based definitions of receipt-freeness for voting

Ashley Fraser and Elizabeth A. Quaglia and Ben Smyth

Abstract

We analyse three game-based definitions of receipt-freeness; uncovering soundness issues with two of the definitions and completeness issues with all three. Hence, two of the definitions are too weak, i.e., satisfiable by voting schemes that are not intuitively receipt-free. More precisely, those schemes need not even satisfy ballot secrecy. Consequently, the definitions are satisfiable by schemes that reveal how voters' vote. Moreover, we find that each definition is limited in scope. Beyond soundness and completeness issues, we show that each definition captures a different attacker model and we examine some of those differences.