1. Ahmed Osama Research Assistant

2. Presentation Outline Winc- Nile University- Privacy Preserving Over Network Coding 2  Introduction  Network coding  Applications of network coding: recent work  Primitives  Linear Network Coding  Traffic analysis  Privacy preserving Scheme  Security proposed scheme  Future work  References

3. Network Coding Winc- Nile University- Privacy Preserving Over Network Coding 3  Network coding is a field of information theory and coding theory and is a method of attaining maximum information flow in a network [Wikipedia]. Pioneering work: [1] R. Ahlswede, N. Cai, S.-Y. R. Li, and R.W. Yeung, “Network information flow,” IEEE Trans. on Information Theory, vol. 46, no. 4, July 2000.

4. Network Coding Winc- Nile University- Privacy Preserving Over Network Coding 4 Example  Simple store and forward  Multicast rate of 1.5 bits per time unit

5. Network Coding Winc- Nile University- Privacy Preserving Over Network Coding 5  X-OR  is one of the simplest form of data coding  Multicast rate of 2 bits per time unit

6. Presentation Outline Winc- Nile University- Privacy Preserving Over Network Coding 6  Introduction  Network coding  Applications of network coding: recent work  Primitives  Linear Network Coding  Traffic analysis “Unobservability Vs Anonymity”  Privacy preserving Scheme  Security proposed scheme  Future work  References

7. Applications of network coding: recent work Winc- Nile University- Privacy Preserving Over Network Coding 7

8. Application 1:Content Distribution Winc- Nile University- Privacy Preserving Over Network Coding 8 Distribute content to millions of users, such as  Software updates  Music  Films Traditional Method Content collected in servers, clients connect to servers to download the information. Problems: Not-scalable, expensive, slow and Single point of failure

9. Application 1:Content Distribution Winc- Nile University- Privacy Preserving Over Network Coding 9  P2P networks: Capacity and computational power of the network increases with the number of users Avalanche Example

10. Application 2:Vehicular Networks Winc- Nile University- Privacy Preserving Over Network Coding 10  Vehicles communicate with each other and with roadside infrastructure to increase safety and optimize traffic. [Y. Lin ;MobiOpp 2007]

11. Presentation Outline Winc- Nile University- Privacy Preserving Over Network Coding 11  Introduction  Network coding  Applications of network coding: recent work  Primitives  Linear Network Coding  Traffic analysis  Privacy preserving Scheme  Security proposed scheme  Future work  References

12. Linear Network Coding Winc- Nile University- Privacy Preserving Over Network Coding 12 The output flow at a given node is obtained as a linear combination of its input flows. The coefficients of the combination are, by definition, selected from a finite field …… x1x1 x2x2 xnxn

13. Network Model Paper Summary- WINC- Nile University13 s ϵ V T ϵ V ; t means one destination Acyclic graph Is the multi cast capacity and x 1 …..,x h Edge symbols comes from a finite field F q y(e) is the symbol carried on edge e (e) is the LEV

14. Network Model Paper Summary- WINC- Nile University14 T ϵ V ; t means one destination Acyclic graph By induction we can calculate that Global Encoding Vector(GEV) g(e) = [g 1 (e),….g h (e)] s ϵ V

15. Network Model Paper Summary- WINC- Nile University15 By induction we can calculate that Global Encoding Vector(GEV) g(e) = [g 1 (e),….g h (e)] Global Encoding Matrix

16. Presentation Outline Winc- Nile University- Privacy Preserving Over Network Coding 16  Introduction  Network coding  Applications of network coding: recent work  Primitives  Linear Network Coding  Traffic analysis  Privacy preserving Scheme  Security proposed scheme  Future work  References

17. Traffic analysis Winc- Nile University- Privacy Preserving Over Network Coding 17  Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication. It can be performed even when the messages are encrypted and cannot be decrypted. In general, the greater the number of messages observed, or even intercepted and stored, the more can be inferred from the traffic.  Passive attack

18. Presentation Outline Winc- Nile University- Privacy Preserving Over Network Coding 18  Introduction  Network coding  Applications of network coding: recent work  Primitives  Linear Network Coding  Traffic analysis  Privacy preserving Scheme  Security proposed scheme  Future work  References

19. Security proposed scheme Winc- Nile University- Privacy Preserving Over Network Coding 19 Problem Statement  Privacy threats exist in network coding since explicit GEVs provide a back door for adversaries.  We need to prevent flow tracing to protect source and destination from being revealed, Specially in multi-hop wireless network.

20. Security proposed scheme Winc- Nile University- Privacy Preserving Over Network Coding 20  Solution  Encoding Global Encoding Vectors using Homomorphic Functions  Homomorphism means operations on plain text can be performed by operating on corresponding cipher text.  We need additive property E(x+y) = Add(E(x),E(y))  Also we need Scalar Multiplicative property E(t.x) = Mul(E(x),t)

21. Presentation Outline Winc- Nile University- Privacy Preserving Over Network Coding 21  Introduction  Network coding  Applications of network coding: recent work  Primitives  Linear Network Coding  Traffic analysis  Privacy preserving Scheme  Security proposed scheme  Future work  References

22. Future Work Winc- Nile University- Privacy Preserving Over Network Coding 22  Propose a scheme that provide less computational overhead.  Authentication vs. privacy tradeoff

23. References Winc- Nile University- Privacy Preserving Over Network Coding 23  [1] Y. Lin, B. Liang, and B. Li, “Performance Modeling of Network Coding in Epidemic Routing,” in Proc. of the First ACM International Workshop on Mobile Opportunistic Networking (MobiOpp), 2007.  [2] S.-Y. R. Li, R. W. Yeung, and N. Cai, “Linear network Coding”, IEEE Trans. on Information Theory, vol. 49, no. 2, Feb. 2003.  [3] R. Ahlswede, N. Cai, S.-Y. R. Li, and R.W. Yeung, “Network information flow,” IEEE Trans. on Information Theory, vol. 46, no. 4, July 2000.  [4] Y. Fan, Y. Jiang, H. Zhu, and X. Shen, "An Efficient Privacy- Preserving Scheme against Traffic Analysis Attacks in Network Coding", Proc.IEEE INFOCOM'09, Rio de Janeiro, Brazil, April 19- 25, 2009.

24. Thank you Any Questions ? Winc- Nile University- Privacy Preserving Over Network Coding 24