IdLenses is a novel interaction concept to realize user-aware interfaces on shared surfaces. Users summon virtual lenses which allow for personalized input and output. The ability to create a lens instantaneously anywhere on the surface, and to move it around freely, enables users to fluidly control which part of their input is identifiable, and which shall remain anonymous. In this paper, we introduce the IdLenses concept and its interaction characteristics. Further, we discuss how it enables the personalization of input and output on shared surfaces.