Securing broadcast based ad hoc routing protocols

Security, particularly integrity and confidentiality, is a prerequisite for using mobile ad hoc networks (MANETs) in sensitive or hostile environments. Existing MANET routing protocols, however, are commonly not designed to ensure, that only authorized nodes can join the MANET. The topology of the MANET and potential points of attack are revealed to (unauthorized) listeners if control messages are sent unencrypted. We propose a modification of the optimized link state routing (OLSR) protocol. In a reference implementation we replaced OLSR's broadcast messages with a set of unicast messages. To provide peer access and control in the mobile environment we issued certificates to all participating nodes and used these for mutual authentication. Additionally, we encrypted all OLSR messages using Internet Protocol Security (IPsec). This method adds additional traffic to the network. We discuss the complexity of our approach and estimate network parameters for which the impact can be considered tolerable.