Updated: 2016 by Cisco Systems
Updated: July 8, 2013, collected from Internet, unknown resource, thanks!
Updated: Nov. 10, 2012 by Jing Sun
Posted on TechJourney, techjourney.net
Updated: ??, by MIMEsweeper
Posted: Nov. 6, 2000, by John Linn, RSA Lab
By Burt Kaliski and Moses Liskov, RSA Lab
Collected from Internet