[1]Wang Xinran, Kohno T, Blakley B. Polymorphism as a defense for automated attack of websites [EBOL]. 2014 [20160411]. http:www.docin.comp1359615721.html[2]Nikiforakis N, Kapravelos A,Joosen W, et al. Cookieless monster: Exploring the ecosystem of webbased device fingerprinting[C] Proc of IEEE Symp on Security and Privacy. Piscataway, NJ: IEEE, 2013[3]Eckersley P. How unique is your web browser[G] LNCS 6205. Berlin: Springer, 2010: 118[4]Gardner P A, Maffeis S, Smith G D. Towards a program logic for JavaScript[C] Proc of the 39th Annual ACM SIGPLANSIGACT Symp on Principles of Programming Languages (POPL 2012). New York: ACM, 2012: 3144