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Trustworthy Sensor Networks

Trustworthy Sensor Networks. Daniel Aegerter, 41542053 Supervisor: Rajan Shankaran. Agenda. Problem Statement Wireless Sensor Networks Notion of Trust in Wireless Sensor Networks Comparative Analysis Recommendations. Problem.

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Trustworthy Sensor Networks

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  1. Trustworthy Sensor Networks Daniel Aegerter, 41542053 Supervisor: Rajan Shankaran

  2. Agenda • Problem Statement • Wireless Sensor Networks • Notion of Trust in Wireless Sensor Networks • Comparative Analysis • Recommendations

  3. Problem • Security is critical in many applications of Wireless Sensor Networks (WSNs) • Battlefield surveillance • Patient monitoring • Environment monitoring • Security mechanisms assume trustworthiness of participating nodes • What happens if nodes get compromised? • Access key material • Change content of messages • Drop messages • Lives and livelihoods might depend on the correctness of the data

  4. Wireless Sensor Networks (WSNs) • Sensor nodes sense data from the environment and detect specific events • Sensor nodes are equipped with sensors to monitor a wide range of physical conditions: • Temperature, Humidity, Light, Pressure, Object motion, Noise, etc. • Sensor nodes are constrained by limited resources Memory Communicationdevice Sensor Unit Processor Unit PowerUnit

  5. Network Architecture • Components of Wireless Sensor Networks • Common Sensor Nodes • Base Station • Multihop communication

  6. Notion of Trust • “Trust is the subjective probability by which an individual, A, expects that another individual, B, performs a given action on which its welfare depends” (Gambetta, 1988) In the context of WSNs • Trustworthy sensor nodes don’t: • Manipulate gathered information • Alter information received from neighbouring nodes • Flood the network with bogus routing information • Drop messages received from other nodes

  7. Challenges in Evaluating Trust for WSNs • Limited processing, storage, and energy resources • Existing protocols and mechanisms are not applicable • Minimise communication overhead • Trusted authority not present in WSNs • Public key mechanisms and certificates not suitable • Adoption of architectural network changes • Dynamic nature of WSNs • Nodes may become faulty or compromised  Trust re-evaluation is essential

  8. Concept of Reputation-Based Trust Systems • Trust is based on a node’s behaviour • Does the node behave in a correct manner? • Network events and correctness of gathered information • Trust evaluation through first and second-hand information • Direct observations • Recommendations from peers • Building blocks • Watchdog mechanism  collects evidence • Reputation system  evaluates and maintains trust

  9. Comparative Analysis • Compares five reviewed reputation-based frameworks • Reputation-based framework for high integrity sensor network (RFSN) • Gaussian trust model and reputation system (GRSSN) • Lightweight group based trust management scheme (GTMS) • Trust-based cluster head election • Certificate and behaviour-based approach • Determines characteristics and constraints of each framework • Proposes categories to conduct the comparative analysis • Trust management • Node and network requirement • Trust evaluation

  10. Comparative Analysis – Some Criteria • Evidence • Network events vs. correctness of sensed data • Pre-established trust relationships • Do sensor nodes trust each other at time of deployment? • Storage complexity • Tables, keys, certificates • Revocation • What happens with non-cooperative sensor nodes?

  11. Comparative Analysis – Outcomes • All frameworks have some design problems • Difficult to take all characteristics and constraints of WSNs into account • Frameworks are application specific • Different assumptions • Different requirements (e.g. supernodes, keys, certificates) • Sophisticated frameworks are more complex • Economical issues • Management issues • Evidence analysis • Network events or also correctness of sensed data?

  12. Recommendations • Collaborative reputation-based approach for establishing trust • Behaviour of nodes is observed by a subset of sensor nodes • Other nodes do not have to monitor network events • Guardian nodes • Guardian nodes evaluate collaborative trustworthiness of nodes • All sensor nodes are directly observable by guardian nodes • Guardian node evaluate whether a node is cooperative • Opinions are shared among guardian nodes • Blacklist entry has to be confirmed by other guardians • Sensor node keep list with non-cooperative nodes

  13. Recommendations - Example

  14. Future Research Directions • Analyse correctness of sensed data not only network events • Trust evaluation for different roles that sensor node can perform • Forward messages • Aggregate data • Sense information Thank you

  15. Questions

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