%0 Journal Article %T Cryptanalysis of Security Enhancement for a Modified Authenticated Key Agreement Protocol %A Kou-Min Cheng %A Ting-Yi Chang %A Jung-Wen Lo %J International Journal of Network Security %D 2010 %I Femto Technique %X Recently, Chang et al. proposed a security enhancement in Ku and Wang's authenticated key agreement protocol. Two parties employ the pre-shared password to agreement a common session key via insecure network. However, in this article, we will show that Chang et al.'s scheme is suffer from the backward replay attack and the off-line password guessing attack. %K Cryptography %K information security %K key agreement %K key exchange %K password %U http://ijns.femto.com.tw/download_paper.jsp?PaperID=IJNS-2009-12-10-1&PaperName=ijns-v11-n1/ijns-2010-v11-n1-p55-57.pdf