Privacy Enhanced Identity Management: Design Considerations and Open Problems

User centric identity management will be necessary to protect user's privacy in an electronic society. However, designing such systems is a complex task, as the expectations of the different parties involved in electronic transactions have to be met. In this work we give an overview on the actual situation in user centric identity management and point out problems encountered there. Especially we present the current state of research and mechanisms useful to protect the user's privacy. Additionally we show security problems that have to be borne in mind while designing such a system and point out possible solutions. Thereby, we concentrate on attacks on linkability and identifiability, and possible protection methods