A common challenge for applications requiring information and knowledge fusion is the conversion of data streams into knowledge adapted to the context of usage. In the context of the project Integrated Mobile Security Kit, this paper focuses on the knowledge fusion sub-system. It integrates different fusion aspects based on a common domain model and embedded into a distributed and mobile infrastructure. The fusion aspects considered are attribute and situation fusion, situation recognition and event correlation. The main contribution of the paper are (1) the architecture of the knowledge fusion sub-system, (2) the domain model for integrating the fusion aspects and (3) the specification of the inner workings of the three different fusion aspects.