This paper makes a summary of seurity of protocols and formal method in chapter 2.Strand Space, brought forward by Fabrega, Herzog and Guttman, is a applied, intuitionistic and strict formal method for security protocols analysis.

• 串空间(STRAND SPACE)模型由Fabrega, Herzog和Guttman三人提出,是分析安全协议的一种实用、直观和严格的形式化方法。