Publish-subscribe system is a messaging system which consists of different types agents where these agents are classified based on their roles. These agents can be the information producers or information consumers. In publish-subscribe system, messages are published by publishers and these messages or events are received by the subscribers based on their subscriptions. Event subscribers describe the kind of events that they want to receive with an event subscription which acts as a filter on the message or event contents. In the content based publish/subscribe system, publishers and subscribers are loosely coupled and they do not trust each other; so providing the basic security mechanisms like authentication and confidentiality in the publish/subscribe system is a difficult task.