Abstract
In the ubiquitous environments, smart cards as an ubiq- uitous computing device provide several services to perva- sive computing and ubiquitous services. In 2006, Shieh- Wang pointed out the weakness of Juang's remote mutual authentication scheme using smart card and further pro- posed a novel remote user authentication scheme using smart card. The current paper, however, demonstrates that Shieh-Wang's scheme does not provide perfect forward se- crecy and is vulnerable to a privileged insider's attack. Keyword: Authentication, Password, Key agreement, Cryptanalysis, Smart card