Security and Privacy in Sensor Networks: Research Challenges

1. Security and Privacy in Sensor Networks: Research Challenges Radha Poovendran University of Washington http://www.ee.washington.edu/people/faculty/radha

2. Outline • Panda-Hunter Game • Sensor Network Security • How is it different? • Incomplete List of challenges • Problem #1- Problem #5

3. Panda-Hunter Game Model • A generic asset monitoring sensor network application • Panda-Hunter Game: • Sensor Network monitors Panda • Hunter observes Panda_Here messages and go after Panda • Panda’s Challenge • Want Location Privacy • Hunter’s Challenge • Want valid message • Want the network to work reliably • Detect any faulty or compromised sensor • Both need different services Data Sink Sensor Node

4. Sensor Network Security • What do we mean by sensor network security? • Conventional view of security from cryptography community: cryptographically unbreakable design in practical sense • Network Reality: very few security breaches in practice are to exploit flaws in cryptographic algorithms; side channel attacks • Malicious versus selfish (DoS vs. resource gobbler) • Security v.s. robustness, fault tolerance, resiliency • Security is not a black/white world, it is progressive • We must secure entire networked system, not just an individual component • Solutions must be robust/adapt to new threats as much as possible

5. How is it Different? • Wireless Sensor networks have NO clear line of defense • Each node is a host as well as a “router” • Security solutions in wired or cellular networks may leverage the networking infrastructure • Secure Network/service “infrastructure” has to be collaboratively established • Wireless channel is easily accessible by both good citizens and attackers • Resource constraints on portable devices • Energy, computation, memory, etc. • Some devices may be compromised • Heterogeneity prevents a single security solution

6. Capability based Abstraction of a Heterogeneous Network Capability-based Abstraction Processing Capabilities Network Granularity BN-Backbone node RN-Regular Node BN BN RN BN RN RN RN RN RN A B

7. Incomplete List of Challenges • Resource-Efficient Secure Network Services • Network Initialization, single/multihop neighbor discovery • Multihop path establishment & Routing • Supporting application services • Cryptographic services • Broadcast authentication • Key management • Security mechanisms for fundamental services • Clock synchronization • Secure location discovery and verification of claims • Location privacy • Secure aggregation and in-network processing • Cluster formation/cluster head election • Middleware (will not discuss further)

8. Incomplete List of Challenges • Modeling vulnerabilities • VERY POOR state of understanding • Needed by services and applications • Cross-layer design techniques • Routing/location-aware protocols that are also robust! • Incorporating semantics such as geometry, radio model and range for context-based security • Functionality instead of optimality

9. Problem #1: Robust Designs • Attacks and compromise of network are reality • Misconfiguration cannot be fully eliminated • Maybe we can never enumerate • Software bugs are #1 cause for all possible attacks • Not every device can implement maximum-strength solutions • Shift from prevention to tolerance • Building trustworthy system out of untrustworthy components • Ability to detect, and function, even in the presence of problems • Similar analogy to IP • building reliable system out of unreliable components • How? Can be application specific

10. Problem #2: Adaptive Security • Adaptation to handle many dimensions of dynamics: • Adaptive to user requirements • Differential security services used in government and military • Adaptive to user devices • Adaptive to channel dynamics: • Partial connectivity, disconnectivity, full connectivity • Adaptive to mobility • Cross-domain service for roaming users • Adaptive to dynamic membership • Node join, leave, fail

11. Problem #3: Joint Design of QoS and Security • Incorporating network metrics and security: scalability, communication overhead, computation complexity, energy efficiency, device capability, … • Different performance metrics may be in (partial) conflict • Probably the most secure system is of minimal usability • Example: energy efficiency/computation complexity versus cryptography strength • Many conventional security solutions take a centralized approach

12. Problem #4: Evaluation of Design • Current designs have an explicit threat model in mind • NOT Realistic • Real trace analysis for practical attacks? • Benchmarking ? • Other areas in computer systems have well defined benchmarks: SPEC CPU, TPC-C • Analytical tools • Current effort: game theory, graph theory

13. Problem #5: Securing the Chain • The system is only as secure as the weakest link • Many supporting components: DNS, ARP, DHCP,… • Other supporting protocols: bootstrapping, discovery, time synchronization • How to secure these supporting components • Often ignored • Secure the entire system chain • Build multiple fences • Each fence is built based on a component’s resource constraint