LAS VEGAS -- Prior to Wednesday's opening keynote by National Security Agency Director General Keith B. Alexander, Black Hat conference founder Jeff Moss commented that he hadn't seen the sort of tension that now exists in the security community since the "encryption wars" of the early 1990's.

That tension was evident not only in the mixed audience reaction to Alexander's talk, but it was also evident in the nature of several zero-day vulnerabilities being announced at Black Hat 2013, the sixteenth annual U.S. gathering of security researchers and corporate security practitioners .