1. 90321011 孫國偉 Efficient Password authenticated key agreement using smart cards Author : Wen-Shenq Juang* Date : 2003.11.26 in Computers & Security

2. Introduction:  What is the smart card What is the smart card  What does it must to have merits What does it must to have merits  Review Chien et al.s(2002) Review Chien et al.s(2002)  Our protocol Our protocol  Security analysis Security analysis

3. What is smart card

4. Main merits: No verification table: UserServer ID1 PW1 ID2 PW2 ID3 PW3.

5. Main merits: Freely chosen password: Users can feely choose Their own passwords

6. Main merits: Lower communication and computation cost: They may not provide a powerful computation capability and high bandwidth

7. Main merits: Mutual authentication: Users and servers can authenticate each other

8. Review Chien et al.s(2002)  The registration phase  The login phase  The verification phase

9. The registration phase ServerUser Smart Card ID = identity PW= password x = server’s secret key

10. The login phase Smart Card Reader Server T = current timestamp

11. The verification phase ServerUser Reject

12. The drawbacks  Time-synchronization problem user’s time and server’s time must differ only in small range  No provide key agreement

13. Our protocol  Registration phase  Login and session key agreement phase

14. The registration phase ServerUser Smart Card ID = identity PW= password x = server’s secret key

15. Login and session key agreement phase

16. Security analysis