1. KAIS T Decentralized key generation scheme for cellular-based heterogeneous wireless ad hoc networks 2015-10-04 임 형 인 Ananya Gupta, Anindo Mukherjee, Bin Xie and Dharma P. Agrawal University of Cincinnati Journal of Parallel and Distributed Computing 2007

2. Contents Introduction Background Decentralized key generation schema Security and Performance Analysis Conclusion 2 / 14

3. Introduction (1/4) Traditional MANET(Mobile Ad hoc NETwork) Purely consist of mobile nodes Absence of the centralized authority Many problems with secure key generation Because no prior trust relationships Solution is pre-distribution of secure key 3 / 14

4. Introduction (2/4) Cellular-based MANET in reality The cellular mobile has more than one cellular medium Bluetooth, Wi-Fi, Infrared, etc  medium of MANET 4 / 14 Cellular infra Bluetooth Wi-Fi Infrared

5. Introduction (3/4) Necessity of MANET in reality Direct communication between mobiles is cheaper Cheaper than communication through Cellular infrastructure Take advantages of cellular infrastructure to MANET Utilizing a cellular network for key management 5 / 14 Authentication from Cellular-infra How to get security? Authentication from Cellular-infra

6. Introduction (4/4) In this paper Propose “Decentralized key generation scheme” for MANET Multiple BS(Base Station) Minimize intervention Scalability of key generation and distribution 6 / 14

7. Polynomial key scheme Two variable for one symmetric calculation Background 7 / 14 1 2 1. Input x 2. Exchange identifier 1. Input x 3. Input y 4. Same value (secret key) Symmetric Property

8. Decentralized key generation schema (1/5) Extended form of polynomial key Four variable for two symmetric calculation 8 / 14 Mobile peer Base Station peer

9. Decentralized key generation schema (2/5) Cellular infrastructure for key management 9 / 14

10. Decentralized key generation schema (3/5) Group-based polynomial Polynomial exchange between Base Stations 10 / 14

11. Decentralized key generation schema (4/5) Polynomial for MS Distributing polynomials to Mobiles 11 / 14

12. Decentralized key generation schema (5/5) Pairwise direct message exchange between Mobiles 12 / 14 EntityID Base Stationi Mobilea EntityID Base Stationj Mobileb

13. Security analysis (1/2) Hazard of K-degree polynomial key Compromise entire secret key by compromising ≥ K nodes Hazard of the polynomial key in this paper 13 / 14 Possible to calculate original function Compromise more than K nodes Once compromise entire network Entity typeCompromise conditionCompromised Base Station≥ K Mobile≥ K 2 Mobile≥ K a BS, b MSaK+b ≥ K 2

14. Security analysis (2/2) Security comparison (Yi Cheng et al.) Bulletproof at sensor node capture attack (while <K) 14 / 14 Polynomial scheme

15. Performance analysis (1/3) Routing overhead in key exchange 15 / 14

16. Performance analysis (2/3) Average latency during the initial key exchange 16 / 14

17. Performance analysis (3/3) Key storage overhead comparison (Yi Cheng et al.) Constant and low storage overhead with whatever size 17 / 14 Polynomial scheme

18. Conclusion Propose a novel method for cellular-based MANET MS can enjoy the same trust in MANET Trust in MS is derived from backbone cellular network Easy key distribution by polynomial key scheme Function key distribution and exchanging identifier 18 / 14