1. SUBJECTIVE LOGIC BASED PROBABILISTIC KEY MANAGEMENT FOR MANETS Mahdieh Ahmadi Performance and Dependability Laboratory Sharif University of Technology Spring 2014

2. Outline Mobile Ad hoc networks(MANETs) Probabilistic Key Management Subjective Logic Proposed Algorithm SL based Probabilsitic Key Managment 2 Mahdieh Ahmadi

3. Mobile Ad hoc Networks Wireless Networks Infrastructure-based Networks Wireless LANs Ad hoc Networks Mahdieh AhmadiSL based Probabilsitic Key Managment 3 Useful when infrastructure not available Impractical Expensive

4. MANETs :: Complexities Mahdieh AhmadiSL based Probabilsitic Key Managment 4 Autonomous and infrastructure less Multi-hop routing Dynamic network topology Device heterogeneity Bandwidth constrained variable capacity links Network Scalability A B A B

5. MANETs:: Complexities Broadcast nature of the communications Lack of mobility awareness by system/applications Short battery lifetime Limited capacities Security Mahdieh AhmadiSL based Probabilsitic Key Managment 5

6. MANETs:: Security Nodes rely on other nodes for communication No centralized trusted authorities Intermediate nodes are able to Read, Drop or Change messages before resending them Mahdieh AhmadiSL based Probabilsitic Key Managment 6

7. Cryptography Symmetric key cryptography Define a shared key between every two node Shared or pairwise Pairwise : every node should store n-1 keys Shared : compromising just one node destroys the security of the whole network Asymmetric cryptography without third party Stores all the public keys in every node Provides authentication, integrity and non-repudiation Mahdieh AhmadiSL based Probabilsitic Key Managment 7 Confidentiality Integrity Authentication Non-repudiation × Availability Confidentiality × Integrity × Authentication × Non-repudiation × Availability

8. Cryptography :: Key Management Mahdieh AhmadiSL based Probabilsitic Key Managment 8 Provide secure procedures for handling cryptographic keying materials

9. Key Management :: Probabilistic Key Management Mahdieh AhmadiSL based Probabilsitic Key Managment 9 j.… Destination Source i j k i.… k.… j a b a b Confidentiality Integrity Authentication Non-repudiation × Availability Need limited capacity Introduced by Gharib et al., 2013.

10. Probabilistic Key Management :: Features Mahdieh AhmadiSL based Probabilsitic Key Managment 10 Connectivity Probability : 99.99% Storing only a few keys instead of all keys

11. Probabilistic Key Management :: Concerns Mahdieh AhmadiSL based Probabilsitic Key Managment 11

12. Subjective Logic Extend probabilistic logic by expressing uncertainty Reason in presence of uncertain or incomplete evidence Prepositions such as “I don’t know” cannot be expressed  ignorance or uncertainty Additivity Principle Sum of mutually disjoint elements in a state space add up to 1 Probabilistic Logic  YES Belief Theory  NO : main reason for creating belief theory Reality  closer to belief theory Mahdieh AhmadiSL based Probabilsitic Key Managment 12 Standard Logic Probabilistic Logic ?? Standard Logic Probabilistic Logic Belief Theory ?

13. Subjective Logic :: Definitions Mahdieh AhmadiSL based Probabilsitic Key Managment 13 Standard Logic Probabilistic Logic Belief TheorySubjective Logic

14. Subjective Logic :: Opinion Mahdieh AhmadiSL based Probabilsitic Key Managment 14

15. Opinion:: Binomial Opinion Mahdieh AhmadiSL based Probabilsitic Key Managment 15

16. Binomial Opinion :: Evidence Notation Mahdieh AhmadiSL based Probabilsitic Key Managment 16

17. Subjective Logic :: Probabilistic Notation Mahdieh AhmadiSL based Probabilsitic Key Managment 17

18. Subjective Logic :: Operators Addition Subtraction Multiplication Division Deduction Abduction Discounting Cumulative fusion Averaging fusion Belief Constraining … Mahdieh AhmadiSL based Probabilsitic Key Managment 18

19. Subjective Logic :: Fusion Mahdieh AhmadiSL based Probabilsitic Key Managment 19

20. Subjective Logic :: Trust Transitivity A trusts B B believes that proposition x is true Agent A will also believe that proposition x is true What is the effect of A disbelieving that B will give a good advice? A thinks that B ignores the truth value of x A thinks that B consistently recommends the opposite of his real opinion about the truth value of x Base Rate Sensitive Discounting Mahdieh AhmadiSL based Probabilsitic Key Managment 20

21. Subjective Logic :: Example Mahdieh AhmadiSL based Probabilsitic Key Managment 21

22. SL Based Probabilistic Key Management Mahdieh AhmadiSL based Probabilsitic Key Managment 22 k Destination a b c d e f g (0, 0, 1, 0.5) (1, 0, 0, 0.5) (0, 0, 1, 0.5) (1, 0, 0, 0.5) (0, 0, 1, 0.5) (1, 0, 0, 0.5) (0, 0, 1, 0.5) (0.7, 0, 0.3, 0.5) C(x, y): node ‘x’ opinion toward node ‘y’ Initial value C(x, y) = (Threshold, 0, (1-Threshold)) Optimistic Threshold > 0.5 Pessimistic Threshold < 0.5

23. SL Based Probabilistic Key Management Mahdieh AhmadiSL based Probabilsitic Key Managment 23

24. SL Based Probabilistic Key Management Mahdieh AhmadiSL based Probabilsitic Key Managment 24 Destination Source i j d s (0.7, 0, 0.3, 0.5) (0, 0, 1, 0.5) (1, 0, 0, 0.5) … (0.7, 0, 0.3, 0.5) … (0, 0, 1, 0.5) (0.7, 0, 0.3, 0.5) (0.49, 0, 0.51, 0.5)

25. SL Based Probabilistic Key Management Mahdieh AhmadiSL based Probabilsitic Key Managment 25

26. Results Should be tested in ns3 Mahdieh AhmadiSL based Probabilsitic Key Managment 26

27. References Mohammed Gharib, Ehsan Emamjomeh-Zadeh, Ashkan Norouzi-Fard, and Ali Movaghar. A novel probabilistic key management algorithm for largescale manets. In Proceedings of the 2013 27th International Conference on Advanced Information Networking and Applications, AINA '13, pages 349-356. IEEE Computer Society, 2013. Anurag Kumar, D. Manjunath, and Joy Kuri. 2008. Wireless Networking. Morgan Kaufmann Publishers Inc., San Francisco, CA, USA. Audun Jøsang. Subjective Logic. Draft book, February 2013. (http://folk.uio.no/josang/papers/subjective_logic.pdf, February 18 2013)http://folk.uio.no/josang/papers/subjective_logic.pdf Mahdieh AhmadiSL based Probabilsitic Key Managment 27

28. THANK YOU