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A simple remote user authentication scheme

A simple remote user authentication scheme. M. S. Hwang, C. C. Lee and Y. L. Tang, “A simple remote user authentication scheme,” Mathematical and Computer Modelling , Vol. 36, No. 1-2, pp. 103-107, July 2002.

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A simple remote user authentication scheme

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  1. A simple remote user authentication scheme M. S. Hwang, C. C. Lee and Y. L. Tang, “A simple remote user authentication scheme,” Mathematical and Computer Modelling, Vol. 36, No. 1-2, pp. 103-107, July 2002. E. J. Yoon, E. K. Ryu and K. Y. Yoo, “An improvement of Hwang–Lee–Tang's simple remote user authentication scheme,” Computers & Security, In Press. Presented by Hsing-Bai Chen (陳星百) 17 Sep. 2004 http://islab.iecs.fcu.edu.tw

  2. Outline • Introduction • Design goals • Hwang-Lee-Tang’s scheme (HLT’s scheme) • Discussions on HLT’s scheme • Improved scheme (YRY’s scheme) • Security analysis • Conclusion • Comments http://islab.iecs.fcu.edu.tw

  3. Remote server Introduction ID, PW User Public channel http://islab.iecs.fcu.edu.tw

  4. Brief summary Remote user authentication Modification attacks Lamport, 1981 Using smart cards to eliminate the risk and cost of maintaining verification tables. Hwang-Li, 2000 Efficiency Security http://islab.iecs.fcu.edu.tw

  5. Design goals • Require no password or verification tables in the server side • Solve replay attacks • Choose and change users password freely • Reveal no passwords to the server http://islab.iecs.fcu.edu.tw

  6. IDi, h(PWi) Compute Ai = h(IDi  x)  h(PWi) Smart card (stored h( ), Ai) HLT's scheme (1/3) • Registration phase: Ui Server Choose IDi, PWi Compute h(PWi) http://islab.iecs.fcu.edu.tw

  7. Login phase: Ui Server Compute Bi = Ai  h(PWi) = h(IDi  x) IDi, Ci, T HLT's scheme (2/3) Compute Ci = h(Bi  T) • Authentication phase: Check IDi Check (TT)  T Verify Ci = h(h(IDi  x)  T) http://islab.iecs.fcu.edu.tw

  8. HLT’s scheme (3/3) • Password change phase: Ui Server Compute Bi = Ai  h(PWi) = h(IDi  x) Select PWinew and compute h(PWinew) Compute Ai = Bi  h(PWinew) Store Ai http://islab.iecs.fcu.edu.tw

  9. Discussions on HLT’s scheme • Suppose the intruder has stolen x • expensive to re-compute the secret hash value • Suppose the smart card is stolen • Altered password • Bi = Ai  h(PW) = h(IDi  x)  h(PWi)  h(PW) • Ai = Bi  h(PW) • Denial of service attack • Speed of detecting wrong password is slow • No mutual authentication http://islab.iecs.fcu.edu.tw

  10. IDi, PWi YRY’s scheme (1/3) • Registration phase: Ui Server Choose IDi, PWi Compute Vi = h(IDi, TTSA,x) Compute Ai = h(IDi, TTSA,x)  PWi Smart card (stored h( ), IDi, Vi, Ai) http://islab.iecs.fcu.edu.tw

  11. Login phase: Ui Server Compute Bi = Ai  PWi= h(IDi, TTSA,x) IDi, C1, T YRY’s scheme (2/3) Verify Bi = Vi Compute C1= h(Bi, T) • Authentication phase: Check IDi Check (TT)  T Compute Bi= h(IDi, TTSA,x) Verify C1= h(Bi, T) Check (TT)  T Compute C2= h (Bi, C1,T) C2, T Verify C2= h(Bi, C1,T) http://islab.iecs.fcu.edu.tw

  12. Select PWinew Compute Ai = Bi  PWinew Store Ai YRY’s scheme (3/3) • Password change phase: Ui Server Compute Bi = Ai  PWi= h(IDi, TTSA,x) Verify Bi = Vi http://islab.iecs.fcu.edu.tw

  13. Security analysis Protect from • Forgery attacks • Replay attacks • Impersonation attacks • Deniable of service attacks • Spoofing attacks No body can compute Bi = h(IDi, TTSA,x) even if x is revealed http://islab.iecs.fcu.edu.tw

  14. Conclusion Achieve • No verification table • Freedom in changing password • Elimination of denial of service attacks • Secure hash value • Mutual authentication • Fast detection of wrong input password • Less computational cost http://islab.iecs.fcu.edu.tw

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