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A password authentication scheme with secure password updating. SEC 期末報告 學號: 89321037 姓名:翁玉芬. Source. Chun-Li Lin and Tzonelih Hwang, Computers & Security, Vol.22, No.1, pp. 68-72, 2003. Outline. Introduction Peryravian-Zunic’s Scheme Hwang-Yen’s Scheme Proposed Scheme
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A password authentication scheme with secure password updating SEC 期末報告 學號:89321037 姓名:翁玉芬
Source • Chun-Li Lin and Tzonelih Hwang, Computers & Security, Vol.22, No.1, pp. 68-72, 2003
Outline • Introduction • Peryravian-Zunic’s Scheme • Hwang-Yen’s Scheme • Proposed Scheme • Conclusions
Introduction • Password scheme • Password authentication protocol • replay attack • password search attack • stolen-verifier attack • Password change protocol • denial of service attack • Key distribution • forward secrecy
Introduction (cont.) • Notations • id: user number • pw: password • Ks: the server public key • {M}Ks : Encryption of M with Ks • rc: random number generated by client • rs: random number generated by server • H(.) : one-way hash function
stolen-verifier attack . id , rc rs id , H( H( id, pw), rc, rs) Access granted or denied Peyarian-Zunic’s Scheme – password transmission Client Server
id , rc rs id , H( H( id, pw), rc, rs), denial of service attack Access granted or denied Peyarian-Zunic’s Scheme – password change Client Server
id , { rc, pw}Ks , H ( rs) id , H (rc, rs) Access granted or denied Hwang-Yen’s Scheme –password transmission Client Server
No forward secrecy id , { rc, pw}Ks receive rc , H ( rs) receive rs id , H (rc, rs) Compute H (rc,rs) Compute H (rc,rs) Access granted or denied one-time token Hwang-Yen’s Scheme -Key distribution Client Server generate rc generate rs
denial of service attack id , { rc, pw}Ks , H( rs) id , H(rc, rs), Access granted or denied Hwang-Yen’s Scheme -password change Client Server
id , { rc, pw}Ks , H( rs) id , H(rc, rs), H( H( new_pw), rs) Access granted or denied Proposed Scheme –password change Client Server
id , Receive receive id , Compute Compute Access granted or denied Proposed Scheme –key distribution Client Server generate x generate y
Conclusions • The password change protocol can protest against denial of service attack • The key distribution protocol can propose forward secrecy