Authentication and authorization are an essential part of any system allowing for information sharing and social interaction. Especially in such social settings

where mobile devices with restricted capabilities and new possibilities (e.g. screen size, ease of localization) are used, there is an increasing need for providing privacy-respecting integrity and access permission mechanisms by considering trade-offs related to usability aspects. In this paper we show how the usability of authentication and authorization related interaction can be enhanced in mobile social settings. This is carried out in our case by using proof-based anonymous credential systems such as Idemix. The requirements analysis is based on various case studies in building collaborative systems and oriented to the needs of the upcoming EU FP7 funded project Di.Me. We also present the prototypic implementation and future work directions.