As data stream management systems (DSMSs) become more and more popular, there is an increasing need to protect such systems from adversaries. In this paper we present an approach to secure DSMSs. We propose a general security framework and an access control model to secure DSMSs. We implement our framework into an existing data stream management system and show that our approach not only works, by protecting the system from major security threats, but also has little impact on the overall system performance.