Publish-subscribe supports asynchronous interactions among processes in a distributed system. A process can describe its interest in messages by performing an operation called subscribe and will be notified about messages which match the specific interest. Provision of basic security mechanisms such as authentication of publishers and sub­scribers and confidentiality of events and subscriptions is difficult in a publish-subscribe system. Authentication is difficult to achieve due to the decoupled nature of interactions be­tween the publishers and subscribers. Similarly confidentiality conflicts with the content based routing. Moreover, confidentiality is harder to address in broker-less environment, where the subscribers are clustered according to their interest. In this thesis, new techniques to provide confidentiality and authentication in a broker­less content-based publish-subscribe built on P2P architecture are presented. Identity­based-encryption is used to provide authentication of publisher and subscriber and confi­dentiality of events. Furthermore, an algorithm is designed to duster subscribers accord­ing to their subscriptions while preserving a weaker notion of confidentiality. Evaluation results show the feasibility of the technique in terms of dissemination latencies and mes­sage overhead.