1. Fair Blind Signature Based Authentication for Super Peer P2P Network Authors: Xiaoliang Wang and Xingming Sun Source: 2009, Information Technology Journal, vol. 8, issue. 6, pp. 887-894 Speaker: Yi-Ru Lin Date: 09/17/2010 1 National Chung Hsing University

2. Outline  Introduction  Related work  Proposed scheme  Security analysis  Comment 2

3. INTRODUCTION 3 Two types of DRM mechanism FBST (Fair Blind Signature Trust)

4.  Protect mechanism  Trace mechanism Two types of DRM mechanism 4

5.  Identity authenticity  Traceability  Privacy protection  Resilience to a large number of peer FBST (Fair Blind Signature Trust) 5

6. RELATED WORKS 6 Fair blind signature Shamir secret sharing

7. 7 Related work – Fair blind signature  Sender, Signer, Trusted entity Sender Trusted Entity Signer Blind Signature Message- signature pairSignature record Trace

8. 8 Proposed Scheme(1/5)  Shamir’s threshold scheme P T : prime number P T ≧ a 0 t : degree of polynomial a 0 : group key Example: t=3 ; a 0 =1234 ; n = 6 g(x) = 94x 2 +166x+1234 (1,1494);(2,1942);(3,2578); (4,3402);(5,4414);(6,5614) g(x) = 94x 2 +166x+1234 g(0) = 1234

9. 9 Content Distribution  Gaussian elimination ( 高斯消去法 ) In the block, Music provider generates k(k>t) different UID value and distributes them in the p2p network. (UID, h0(UID)) Example H0(UID)’=a+b(UID)’ H0(UID)’’=a+b(UID)’ ‘ 2x+y-z=8 -3x-y+2z=-11 -2x+y+2z=-3 2 1 -1 | 8 -3 -1 2 | -11 -2 1 2 | -3 2 1 -1 | 8 0 1/2 1/2 | 1 0 0 -1 | 1 1 0 0 | 2 0 1 0 | 3 0 0 1 | -1 Assumption UID’=3, UID’’=2, H0(UID)’=10, and H0(UID)’’=5 10=a+3b 5=a+2b a=-5, b=5 => H0(UID)= -5+5(UID)

10. 10 Related work – Shamir secret sharing

11. PROPOSED SCHEME 11 Initialization Local signature Threshold pair sharing Anonymous and authentication communication Trace malicious peer

12. 12 Initialization RP u SP Choose: n=pq RSA-like keys: Public: e Private: d e·d= 1(mod(p-1) ·(q-1)) Secure hash function h(·) Publish: (e, n), h(·) Choose: S RP (·) Choose: S u (·) h u (·) …………… h x (·)……….. ID Hash function uh u (·)

13. 13 Local signature RP u SP

14. 14 Threshold pair sharing RP u SP

15. 15 Anonymous and authentication communication RP u SP

16. 16 Trace malicious peer RP u SP

17. SECURITY ANALYSIS 17 Fundamental security objectives Impersonate Tamper Peer compromise Anonymity Traceability

18. 18 Comments

19. 19 Thanks for your listening