Energy-efficient placement/activation algorithms for authorization servers in sensor network

Sensor networks are resource constrained environments and not physically secured. Sensor nodes may be physically captured and reverse engineered by the attacker. The goal of our research is to design energy-efficient distributed authorization servers (DAS) resilient to logical attack (hacking) and physical attack. We propose to organize our DAS as a layered directed acyclic graph (DAG). Any request to a sensor must be routed through and authorized by every layer of the DAG. Similar concepts have been investigated by other researchers. Our research adds a structural component to the existing research. A common method for achieving longer life for a sensor network is to deploy redundant nodes and activate only a subset of nodes at one point of time. To the best of our knowledge, nobody addressed the problem of choosing the nodes to be activated. In This work we designed a set of algorithms to choose the set of nodes for forming the DAS between the command and control centers (CCCs) and sensors collecting data. Our algorithms maximize the time required to compromise the security as well reduces the energy requirement for authorization and communication.