Dynamic enforcement of decentralized security policies

Abstract: This thesis explores defining security policies in a decentralized setting and dynamic methods of enforcing such policies. In a decentralized setting, principals are free to trust or distrust other principals. The key challenge is to provide possibilities for expressing and enforcing expressive decentralized policies. With foundation in security lattices, we develop a framework for decentralized policies for both confidentiality and declassification. The framework for describing policies takes into account the security policy of all involved principals. To enforce these policies in a highly dynamic setting, such as a web mashup, the thesis proposes a series of monitoring techniques. In particular, we investigate inlining of security monitors, a task which is made more complicated by dynamic code evluation fetures. We consider monitors executing in an environment under the influence of an attacker, identifying both attacks and how they are mitigated through use of defensive programming patterns.