Charles Reis Steven D. Gribble Tadayoshi Kohno Nicholas C. Weaver Detecting In-Flight Page Changes with Web Tripwires. 31-44 2008 NSDI http://www.usenix.org/events/nsdi08/tech/full_papers/reis/reis.pdf conf/nsdi/2008 db/conf/nsdi/nsdi2008.html#ReisGKW08