Measuring Anonymity Revisited

Anonymous message transmission systems are the building blocks of several high-level anonymity services (e.g. epayment, e-voting). Therefore, it is essential to give a theoretically based but also practically usable objective numerical measure for the provided level of anonymity. In this paper two entropybased anonymity measures will be analyzed and some shortcomings of these methods will be highlighted. Finally, source- and destination-hiding properties will be introduced for so called local anonymity, an aspect reflecting the point of view of the users