Cryptanalysis of Verifier-Free Password Authentication Schemes Using Smart Cards

• Main Authors: Hsiu-Mei Chuang, 莊秀美
• Other Authors: Wei-Chi Ku
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/30051392783914948453

碩士 === 輔仁大學 === 資訊工程學系 === 93 === A common feature of conventional password authentication schemes is that a password verification table, which contains the verifiers of users’ passwords, should be securely stored in the server. If the password verification table is stolen or modified by the adversary, the sys-tem is under danger. To solve such problems, many verifier-free password authentication schemes have been proposed. In 2000, Hwang and Li proposed a verifier-free password au-thentication scheme using smart cards based on ElGamal’s public-key technique. Independ-ently, Sun also proposed a verifier-free password authentication scheme using smart cards based on cryptographic hash functions. However, both Hwang-Li’s scheme and Sun’s scheme were vulnerable to several attacks. Later, Chien, Jan and Tseng proposed an improved version of Hwang-Li’s scheme. In addition, Wu and Chieu also proposed an enhanced version of Sun’s scheme in that the user can freely choose and change his password. However, the au-thors themselves showed that their scheme is vulnerable to a forgery attack and then proposed an improved scheme. Since Chien-Jan-Tseng’s scheme and Wu-Chieu’s improved scheme are designed for the single-server architecture, it is inconvenient for the user to access the multi-ple servers in that he has to register with each server individually and possibly should re-member different identities and passwords. And therefore, Juang proposed an efficient veri-fier-free password authenticated key agreement scheme using smart cards for the multi-server architecture. However, we find that these newer schemes still have several weaknesses and drawbacks. In this thesis, we show that Chien-Jan-Tseng’s scheme is vulnerable to a reflection attack, a privileged insider’s attack and is not reparable, and Wu-Chieu’s improved scheme is vulnerable to a stolen smart card attack, a forgery attack, a privileged insider’s attack and an off-line password guessing attack. And, we also demonstrate that Juang’s scheme is vulner-able to a privileged insider’s attack and is not reparable. Furthermore, Juang’s scheme does not provide forward secrecy and the user eviction mechanism.