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Further Security Enhancement for Optimal Strong-Password Authentication Protocol

Further Security Enhancement for Optimal Strong-Password Authentication Protocol. Tzung-Her Chen, Gwoboa Horng, Wei-Bin Lee ,Kuang-Long Lin 3/27/2004. Outline. Introduction Review of Ku-Chen scheme

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Further Security Enhancement for Optimal Strong-Password Authentication Protocol

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  1. Further Security Enhancement for Optimal Strong-Password Authentication Protocol Tzung-Her Chen, Gwoboa Horng, Wei-Bin Lee ,Kuang-Long Lin 3/27/2004

  2. Outline • Introduction • Review of Ku-Chen scheme • The problem of Ku-Chen scheme • The proposed scheme • Security Analysis • Conclusions

  3. Introduction • In 2000, Sandirigama et al. proposed SAS scheme lowered storage, processing, and transmission overheads. • In 2001, Lin, Sun, and Hwang proposed an enhanced password authentication scheme, called the OSPA.

  4. Introduction • In 2002,OSPA protocol has been shown vulnerable to the stolen-verifier attack and the impersonation attack. • In 2003, Ku and Chen proposed a new improved version for the OSPA protocol • In this paper, an improved scheme with mutual authentication is proposed.

  5. Review of Ku-Chen scheme • Notation: h(.) : collision-resistant hash function T : login times k : long-term secret key  :exclusive-or operation

  6. Review of Ku-Chen scheme • Registration phase • Authentication phase

  7. Chooses his identity ID and password PW and computes h2(PW 1) ID, h2(PW 1) Calculates verifier v1=h2(PW 1)h(ID k) Store {ID, v1,T=1} into the verification table

  8. ID, service request Find i from verification table by the ID T=i c1=h(PW i)h2(PW i) c2=h2(PW (i +1))h(PW i) c3=h(h3(PW(i +1))T)

  9. c1,c2,c3 Check c1, c2 Get h2(PWi) by vi h(ID k) y1=c1h2(PWi)=h(PW i) y2=c2y1=h2(PW(i+1)) Check if h(y1)=h2(PWi) h(h(y2) T)=c3 vi+1=h2(PW(i +1))h(IDk) Store ID ,T=i+1, and vi+1

  10. The problem of Ku-Chen scheme • The user is authenticated by the remote server. • But, remote server is not authenticated by the user (Server impersonation attack ).

  11. The proposed scheme • Registration phase • Authentication phase

  12. ID, h2(PW 1) Chooses his identity ID and password PW and computes h2(PW 1) Calculates verifier v1=h2(PW 1)  h(ID k) Store {ID, v1} into the verification table

  13. choose r randomly and compute r h2(PW i) Get h2(PW i) by vi  h(ID k) ID, r h2(PW  i) r =(r h2(PW  i)) h2(PW  i) h(r)h2(PW  i) Check r c1=h(PW i)h2(PW i) c2=h2(PW(i +1)) h(PW i) c3=h(h3(PW(i +1))T)

  14. c1,c2,c3 Check c1, c2 y1=c1h2(PWi)=h(PW i) y2=c2y1=h2(PW(i +1)) Check if h(y1)=h2(PW i) h(h(y2)T)=c3 vi+1=h2(PW(i +1))h(IDk) Store ID and vi+1

  15. Security Analysis • Password guess attack • Impersonation attack • Stolen-verifier attack • Server impersonation attack

  16. Conclusions • We point out the possible server impersonation problem in the Ku-Chen scheme and propose an enhanced version. • The proposed concept of security enhancement is also suitable for the other SAS-like schemes.

  17. THE END

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