Scalable and Privacy-Preserving Variants of the Austrian Electronic Mandate System in the Public Cloud

The current Austrian electronic mandate system, which allows citizens to act as representatives for other citizens or companies in e-Government services, relies on a centralized deployment approach. Thereby, a trusted central service generates and issues electronic mandates on the fly for service providers. The usage of this service is continuously increasing and high loads can be expected in the near future. In order to mitigate the associated scalability issues, this service could be moved into the public cloud. However, a move of a trusted service into the public cloud brings up new obstacles, especially with respect to citizens´ privacy. In this paper we propose two approaches how this move could be successfully realized by preserving citizens´ privacy and still being compliant to national law. The main objectives we focus on are minimal data disclosure to untrusted entities by still keeping the existing infrastructure nearly untouched. We present both approaches in detail and evaluate their capabilities with respect to citizens´ privacy protection as well as their practicability and conclude that both approaches are entirely practical.