1. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems Assurance-aware Self-organization of Sensor Networks Chutima Boonthum, Irwin Levinstein, Stephan Olariu, Lan Wang, Qingwen Xu {cboont, ibl, olariu, walng_l, xu_q}@cs.odu.edu Department of Computer Science, Old Dominion University Norfolk, VA 23529 USA

2. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 2 Background & Motivation Wireless Sensor Networks (WSNs) have been widely used in various applications Securing WSNs has become a major issue and has number of proposed solutions Yet, none of these addresses the issue on information assurance Therefore, we explored various aspects related to “information assurance in WSNs”

3. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 3 Agenda WSNs overview Sensors and sensor networks Information assurance System longevity Securing individual sensors Self-organization Assurance-awareness

4. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 4 Sensors & Sensor Networks Sensor fundamental constraints 1.Sensors are anonymous 2.Modest non-renewable power 3.Sleep most of the time 4.Work unattended 5.Modest transmission range WSNs are multi-hop, limited no of sensors, and unknown topology

5. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 5 Information Assurance Network survivability Ability to function for a long period of time Information survivability Ability to have uninterrupted and secure access to information on network Network security Basic security services at network level Information security Secure information flow

6. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 6 System Longevity Appropriate sleep-wake schedules To save the energy Optimal workforce To provide results satisfying a number of quality of service requirements Topology and coverage control To enhance the effective functional lifetime of the network

7. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 7 Securing individual sensors Tampering/ Tamper resistance Trying to force open an individual sensor Blanking out memory, or Configuring the security service using frequency hopping and cryptographic keys. Physically removing sensors from the deployment area Establishing Signature Array (SA) of sensor’s neighborhood using signal strengths, immediately after deployment. If the sensor do not anymore receive the signals correspond with those in SA, then blank out memory

8. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 8 Assurance-aware Self-Organization A powerful multi-hop communication network capable of utilizing the limited resources of sensors in adaptive and efficient way Energy efficiency sensors need to sleep most of the time Adaptivity Virtual infrastructure adapts to network size, topology, density, and application requirement Multi-hop system Virtual infrastructure supports efficient multi-hop communication

9. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 9 Leader Election When sensor wakes up, it starts to listen for a beacon frame time period. If it has not received, that itself becomes a leader and start sending the “Beacon Packet” If it does, it then becomes a member of that cluster. T: sleeping period F: beacon frame length

10. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 10 Beacon Frame Beacon slot (B) – sending time of each beacon frame Collision slot (C) – reserved for member to report potential collision Wakeup slot (W) – reserved for member to wake up leaders Member slots (M) – for member to send messages to the cluster leader

11. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 11 Collision Resolution When a sensor receives some short beacon packets that are close to cause the collision problem, it sends a collision packet at its leader’s Collision slot and reset its listening timer. If a leader hears anything in its Collision slot, it selects another time to send its beacon packet.

12. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 12 Competing for slots A member randomly chooses a slot from “free” Member slots in the beacon frame and send a report packet twice (at Wakeup slot and at the chosen slot). The leader will confirm if the package arrive; otherwise, a member will choose another “free” a lot and resend the packet. If two members sent data on the same M-slot, the leader will receive no packet at that slot due to noises.

13. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 13 Maintaining the virtual infrastructure Every sensor needs to listen for a beacon frame once in a while Old leaders may fail and new leaders may show up When a leader dies, a part of network needs to be reorganized. Hence, leader reelection is triggered.

14. NCS-2006 March 29-31, 2006 Chiang Mai, Thailand The IASTED International Conference on Networks and Communication Systems 14 Conclusion We surveyed number of issues related to setting up the infrastructure that leveraged by information assurance Leader election, Beacon frame, Collision resolution, Competing for slots, Maintain the virtual infrastructure Research toward a solution is ongoing.