Abstract
Coercion resistance and receipt freeness are critical properties for any voting system. However, many di fferent de finitions of these properties have been proposed, some formal and some informal; and there has been little attempt to tie these definitions together or identify relations between them. We give here a general framework for specifying di fferent coercion resistance and receipt freeness properties using the process algebra CSP. The framework is general enough to accommodate a wide range of defi nitions, and strong enough to cover both randomization attacks and forced abstention attacks. We provide models of some simple voting systems, and show how the framework can be used to analyze these models under di fferent de finitions of coercion resistance and receipt freeness. Our formalisation highlights the variation between the defi nitions, and the importance of understanding the relations between them.