1. Author:YongBin Zhou, ZhenFeng Zhang, and DengGuo Feng Presenter:戴士桀
Cryptanalysis of the End-to-End Security Protocol for Mobile Communications with End-User Identification/Authentication
Author:YongBin Zhou, ZhenFeng Zhang, and DengGuo Feng
Presenter:戴士桀

2. Outline INTRODUCTION REVIEW OF CHANG et al.’S PROTOCOL
CRYPTANALYSIS OF CHANG et al.’S PROTOCOL
MODIFYING THE BP PROTOCOL
CONCLUSION

3. INTRODUCTION MUTUALLY authenticated key agreement protocol
Chang et al. proposed an end-to-end security protocol for mobile communications with end-user authentication.

4. REVIEW OF CHANG et al.’S PROTOCOL

5. REVIEW OF CHANG et al.’S PROTOCOL
Subscriber Identity Module (SIM) card
The subscriber account information and the personal certificate of the mobile user are stored in the SIM
The SIM card is stolen, the conspirator may impersonate the register to communicate with anyone.
Password is involved to construct the end-to-end security authentication protocol

6. REVIEW OF CHANG et al.’S PROTOCOL
Previous study
Messages between the MS and the BS are in encrypted form
Messages between the two BSs are usually in clear form.
Security breach
Messages should be encrypted by a secret session key known only by the two MSs.

7. REVIEW OF CHANG et al.’S PROTOCOL
Park’s protocol

8. REVIEW OF CHANG et al.’S PROTOCOL
Park’s protocol
g be a generator of the multiplicative group , where p is a prime
Private key of MS is ∈ ,andthe public key is = mod p
the private and public keys of BS are ∈ and = mod p

9. REVIEW OF CHANG et al.’S PROTOCOL
Impersonation attack against Park’s Protocol.

10. REVIEW OF CHANG et al.’S PROTOCOL
Impersonation attack against Park’s Protocol
R = ( )−( ) = ( − )
E can easily recover the current session key by computing

11. REVIEW OF CHANG et al.’S PROTOCOL
certificate-based authentication and session key agreement protocol
session agreement protocol is based on the Diffie-Hellman key exchange protocol

12. REVIEW OF CHANG et al.’S PROTOCOL
The basic authentication protocol

13. REVIEW OF CHANG et al.’S PROTOCOL

14. REVIEW OF CHANG et al.’S PROTOCOL
The end-to-end security protocol.

15. REVIEW OF CHANG et al.’S PROTOCOL
EBP to support end-user authentication.

16. CRYPTANALYSIS OF CHANG et al.’S PROTOCOL
Impersonation attack against BP Protocol.

17. MODIFYING THE BP PROTOCOL

18. Conclusion
In this letter shown that the end-to-end security protocol for mobile communications with end-user authentication due to Chang et al. is insecure against impersonation attack.
Proposing a modified protocol can preserves the claimed security.