1. www.Mohammad.Ehdaie.com Introduction to Ad-hoc & Sensor Networks Security In The Name of God ISC Student Branch in KNTU 4 th Workshop Ad-hoc & Sensor Networks Security

2. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 2

3. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 3

4. Ad-hoc Network: Motivation April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 4

5. Ad-hoc Network: Properties  Without any Infrastructure (Self-Organized)  Minimal Configuration & Quick Deployment  Dynamic Topology  Each Node Participates in Routing  Constrained Resources  Battery Power  Wireless Transmitter Range  Computational Power April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 5

6. Ad-hoc Network: Applications  Started by DARPA (1970s)  Military Conflicts  Emergency Services or Natural Disasters  Commercial Environments  Location-Aware Services  Entertainment April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 6

7. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 7

8. Sensor Network: Definition  A Collection of Sensors  Gathering and Sending Information  Self-Organized  Similar to Ad-hoc Network  Monitoring  Sending Alarms  On-Demand Querying Information April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 8

9. Sensor Node  Micro Controller  Radio Transceiver  Battery  Sensor  Temperature  Motion  Pollution  … April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 9

10. Sensor Network: Applications  Battlefield Surveillance  Industrial Process Monitoring  Environment Monitoring  Forest Fire Detection  Air Pollution Monitoring  Greenhouse (Humidity & Temperature)  Health Care (Tracking Patients, …)  Traffic Control  Home Automation  … April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 10

11. Sensor Network: Properties  Lots of Sensors  Spread Randomly over Target Area  Not Controlled by Human  No Movement (often)  Size & Cost Constraints  More Tight Constraints on:  Power Consumption  Memory Size  Computational Power  Communicational Power April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 11

12. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 12

13. Security Issues Vulnerabilities:  Broadcast Channel  Physical Access to Nodes  Cannot be made Tamper Proof Why Standard Models Are not Applicable?  Computational Constraints  Memory Constraints  Infeasibility of Public-Key Cryptosystem  Some More Considerations on Private -Key Cryptosystem April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 13

14. Key Management  Key Distribution (or Pre-Distribution)  Key Discovery  Key Establishment  Key Update April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 14

15. Key Distribution Which node should store which keys? April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 15

16. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 16

17. Trivial Schemes April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 17 Single Master Key Distinct Pair-wise Keys Large Memory Low Security Infeasible

18. Evaluation Metrics  Memory Usage  Connectivity  Processing Overhead  Communication Overhead  Resiliency Against Node Capture April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 18

19. Evaluation Metrics (cont’d) April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 19 Fail (s) = % Compromised Links When s Nodes Are Compromised Fail(s) s 1 1 Single Master Key Fail(s) s 1 1 2/N N-1 Distinct Pair-wise Keys

20. Classification- I April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 20 DeterministicProbabilistic Large Number of Keys 2 Keys in each node  Connected Communicational & Computational Overhead Arbitrary Features

21. Classification- II April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 21 Location Independent Location aware Better PerformanceMore Realistic

22. Classification- III April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 22 Homogenous Hierarchical Resilient against more overhead Easier to Establish- More Realistic

23. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 23

24. Blom Polynomial Scheme April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 24 m m n n

25. EG Probabilistic Scheme April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 25 Connected with arbitrary probability near 1

26. Liu Scheme April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 26

27. Transversal Design Scheme April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 27

28. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 28

29. Fail(s) for EG Scheme It is claimed that Fail(1) = k/P sometimes < 2/n Assumption: 1 node is captured Event A = An arbitrary link is compromised Event B = The captured node is one end of the considered link Fail(1) = Pr{A} = Pr{A|B}Pr{B} + Pr{A|B’}Pr{B’} Pr{B} = 2/n  Pr{B’} = 1 – 2/n Pr{A|B} = 1 Pr{A|B’} = k/P  fail(1) = 1 * 2/n + k/P * (1-2/n) ≈ 2/n + k/P April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 29

30. Comparison April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 30 SchemeAvg hopsMemoryFail(1) Pair-wise1n-12/n Blom1k2/n. EG2-qk2/n + k/P Liu 2-k/(n-1)  2 k=n/m+m-2 2√n < k < n-1 2/n TD(k,√n)1<2-k/(√n+1)<2k < √n1 / √n

31. Outline  Ad-hoc Networks  Sensor Networks  Motivation for Security Issues  Key Distribution Schemes  Some Basic Schemes  Calculation of Their Parameters  An Improvement April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 31

32. An improvement to EG April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 32

33. An improvement to EG April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 33

34. Result April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 34 Pr{Share a common Key} Memory Size

35. Resiliency against node capture Broken Completely: 2 / n + k 2 / P 2 2k / P of links (Half Security) April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 35

36. References April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 36 [1] R. Blom, "An optimal class of symmetric key generation systems", in: T. Beth, N. Cot, I. Ingemarsson (eds.), Advances in Cryptology -EUROCRYPT ’84, vol. 209 of LNCS, Springer-Verlag, pp. 335–338, 1985. [2] C. Blundo, A. D. Santis, A. Herzberg, S. Kutten, U. Vaccaro, M. Yung, "Perfectly-secure key distribution for dynamic conferences", in: E. F. Brickell (ed.), Advances in Cryptology -CRYPTO ’92, vol. 740 of LNCS, Springer-Verlag, pp. 471–486, 1992. [3] Y. Cheng, D. P. Agrawal, “An improved key distribution mechanism for large-scale hierarchical wireless sensor networks”, ELSEVIER Ad Hoc Networks 5, pp. 35–48, 2007. [4] J. Lee, D. R. Stinson, "On the construction of practical key predistribution schemes for distributed sensor networks using combinatorial designs", ACM Trans. Inf. Syst. Secur. 11 (2), pp. 1–35, 2008. [5] S. A. Camtepe, B. Yener, "Key distribution mechanisms for wireless sensor networks: a survey", Tech. Rep. TR-05- 07, Rensselaer Polytechnic Institute, 2005. [6] K.M. Martin, M.B. Paterson, D.R. Stinson."Key Predistribution for Homogeneous Wireless Sensor Networks with Group Deployment of Nodes". Cryptology ePrint Archive, 2008. [7]A. Parakh, S. Kah, "A Key Distribution Scheme for Sensor Networks Using Structured Graphs", arxiv e-Print archive, 2010.

37. References April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 37 [8]J. Lopez, J. Zhou. "Wireless Sensor Network Security". IOS Press, 2008. [9] M. Ren, J. Jaworski, K. Rybarczyk, "Random key predistribution for wireless sensor networks using deployment knowledge", 8th Central European Conference on Cryptography, 2008. [10] H. Chan, A. Perrig, D. Song, "Random Key Predistribution Schemes for Sensor Networks", Proceedings of the 2003 IEEE Symposium on Security and Privacy, p.197, 2003. [11]L. Eschenauer, V.D. Gligor. "A Key-Management Scheme for Distributed Sensor Networks". Proceedings of the 9th ACM conference on Computer and communications security, pp 41-47, 2002

38. April 14-15, 2011 Intro. to Ad-hoc & Sensor Networks Security 38 Thank you!