1. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Network Security Term Project (2002 Fall) 발표자 : 최철준 학 번 : 20022153 Class : Network Security Professor : Kwang-jo Kim

2. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Topic : Forward Secrecy and It’s Application Subject : Forward Secrecy in Proxy Signature

3. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Table of Contents 1.Introduction 2.Main subject of this project - What is Proxy Signature? - What is Forward Secrecy 3. Conclusion

4. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim What is Proxy Signature  Proxy Signature scheme - Delegation of signing capability : An original signer delegates her signing capability to a proxy signer - Proxy signing : The proxy signer creates a proxy signature on behalf of the original signer Referenced by Byong cheon Lee Lecture note

5. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim What is Proxy Signature (cont..)  Security Requirements 1. Verifiability 2. Strong unforgeability 3. Strong Indentifiability 4. Strong Undeniability 5. Prevention of Misuse

6. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim [BC93] B.C Neuman, “Proxy-based authorization and accounting for distributed systems.” Proc 13 th International Conference on Distributed Computing Systems (1993) 283- 291 [MUO96] M. Mambo, K. Usuda, E.Okamoto, “Proxy Signature: Delegation of the Power to Sign Messages”, IEICE Trans. Fundamentals, E79-A:9 (1996) 1338-1353 [KPW97] S.Kim, S.Park, and D.Won, “Proxy Signature, revisited”, Proc of International Conference on Information and Communication Security (1997) 223-232. [LKK01A] B. Lee, H.Kim, K.Kim, “Strong Proxy signature and its Applications.” Proc of SCIS (2001) 603-608. [LKK01B] B. Lee, H.Kim, K.Kim, “Secure Mobile Agent using Strong Non-designated Proxy Signature.” Australasian Conference on Information Security and Privacy (2001) 474- 486 Related Work

7. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Schnorr-based Proxy Signature Original Signer’s Parameter Verification Proxy Signer Key Generation Referenced by Byong cheon Lee Lecture note

8. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Schnorr-based Proxy Signature Proxy Signer Verifier Referenced by Byong cheon Lee Lecture note

9. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim What is Forward Secrecy  Definition of Forward Secrecy - Forward Secrecy : Compromise of the current secret key does not enable an adversary to forge signatures pertaining to the past [Bellare et. al.]

10. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Ross Anderson, “Two Remarks on Public Key Cryptology.” Invited lecture, CCCS ’97. M. Bellare and S. Miner, “A Forward-Secure Digital Signature Scheme.” Crypto ’99. J. Katz, “A Forward-Secure Public-Key Encryption Scheme.” Crypto 02’ rump session. U. M.Maurer, Y. Yacobi, “A Non-interactive Public-Key Distribution.” Designs, Codes and Cryptography v9, no 3 pp 305-316. Related Work

11. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Relationship b/w Proxy Signature and Forward secrecy  People are not concerned about key destroying in Proxy signature.  The key revocation and escrow problem is also important issue in proxy signature.  Some researchers worried about forgery of original signer but it is also possible that proxy signer can recreate forged proxy signature after the key was revoked.

12. Network Security Term Project 2002 Fall Network Security Chul Joon Choi 2002. 10.08 Prof. Kwang jo Kim Conclusion and Future Work - Survey the Proxy Signature and Forward Secrecy - Bring up the Problem in Proxy Signature - Key revocation problem & proxy signer’s forgery - How to merge between Proxy Signature and Forward Secrecy