In this paper1 we discuss the security requirements for mediation, and present our approach towards satisfying them, with an emphasis on con dentiality and authenticity. Furthermore we outline the design of the basic security mechanisms for mediators. Our basic approach suitably combines the concepts of credentials, for authentic authorization with some kind of anonymity, and of asymmetric encryption, for con dentiality, and it can be extended to include additional mechanisms like digital signatures and ngerprints. Additionally it adopts the model of role based security policies because of its application orientation and of its potentials to integrate and unify various policies.