A Design for Secure and Survivable Wireless Sensor Networks Yi Qian, Kejie Lu, David Tipper Presented by: William Newton University of Maryland, Baltimore County

What is a Wireless Sensor Network? A Wireless Sensor Network (WSN) is a network of motes and base stations that communicate with each other over a wireless medium. Mote - battery operated node with limited computing and processing capabilities. Base Station (BS) – node with high computing capabilities. Examples: Military command and control, health-care, weather

Limitations & Environment Conditions Mote Lifespan – Dependent on the battery  Limits computations Cannot execute heavy crypto functions such as AES  Limits wireless communications Efficient power control Various Types of Attacks  Jamming (DoS), Sleep Deprivation Attack, Man in the Middle Attack, Sybil Attack, Physical Security Environmental Factors

Security and Survivability Security  Confidentiality – protect data from being viewed  Authentication – verify that data came from the “true” source  Integrity – protect data from modification  Secure Management Base station level Provide key management services Survivability  Reliability – maintain functionality (even if some nodes fail)  Availability – ensures network accessibility when it is required.  Energy Efficiency – preserve battery life

Architecture

Key Management Scheme Must maintain a keying scheme without “hogging” battery life Key Management Solutions  Single shared key – Not a good idea  Pairwise key scheme – Not your traditional slice of pie Challenge - distribute the keys (or keying materials) to each node before deployment in a secure fashion. Methods  Pre-distributed keys  Dynamically generated keys (from keying materials) Three Steps

Dynamically Generated Keys Keying Materials – polynomial key pool based Three Steps  Step 1: Initialization – distributing polynomial shares  Step 2: Direct Key Two nodes attempt to establish a session key  Step 3: Path Key Setup (Step 2 Failed) Establish a pairwise key with the aid of other sensors on the network Must consider the current condition of the network (who can and can’t we trust?)

Assumptions Not all of the motes are identical Two types of motes were used for testing  C1  Weaker motes  C2  Stronger motes (Focus was not based around the base stations) Metrics  Security: Scalability, efficiency, resilience, reliability  Survivability: Scalability, efficiency, key connectivity, resilience, reliability

Findings Resilience of the key management scheme under attack conditions (Number of C2 motes vary) Additional C2 motes provides stronger resilience and reliability

Findings (cont) Resilience of the key management scheme under attack conditions with different key pool sizes Larger key pools provide stronger resilience. Tradeoff – resilience and reliability

So What’s Missing? What the paper did not address…  What happens if a C2 mode is compromised?  Efficiency of the key management scheme  Attacks on key management scheme Intruder “sneaking” around Key replay attack Key authentication (good node/bad node)

Questions?