Modeling X.509 Certificate Policies Using Description Logics

Public Key Infrastructures are gaining importance in today's IT environment for managing certificates and keys. It is recognized, that the quality and trustworthiness of certificates depend to a large extend on the practices and procedures a certification authority applies when issuing certificates. These procedures are documented in certificate policies, which are generally text-based documents and therefore cannot be processed by machines. This paper describes a framework based on description logics that addresses this situation. Subsumption will be used to compare policies. Based on a case study of modeling real policies some features of this framework will be described. Learnings and an outlook of future work conclude this paper.