Joseph DeTrani, a long-time CIA official who served as a U.S. envoy in talks with North Korea regarding its nuclear activities, will open the hackers' conference on August 2 with a speech about weapons of mass destruction and cyber technology. Former Air Force General Robert Elder, who created one of the U.S. military's first cyber units, will speak the following day. Def Con founder Jeff Moss said the two had been invited long before his July 11 request that federal officials stay away from the convention to defuse tensions over the U.S. mass surveillance programs leaked by former National Security Agency contractor Edward Snowden. Moss said that having former U.S. officials at the conference could be useful to the hacking community because they are uniquely placed to help explain the government's position on the surveillance programs. "Being former, not current, they might be able to speak more freely and offer a more nuanced perspective," said Moss, who is known in hacking circles as The Dark Tangent. "They would probably offer more credible perspective that people are not going to just dismiss out of hand and say ‘Of course you are going to say that. That's your job,'" he said in an interview.

Def Con - short for Defense Condition, in military speak - has since 1992 been bringing together people with a common interest in software, computer architecture, and any high-tech system that can be hacked. It typically attracts a small contingent of officials from the CIA, NSA, FBI, and military among hackers, researchers, security workers, activists and others. The conference this year is expected to draw 15,000 people.

DeTrani told Reuters that after his speech he will address surveillance programs, if asked.

"Everything I've heard about these programs is that they were authorized with oversight. From what I know Americans were not spied upon," he said. "Hopefully nobody throws marshmallows at me and says ‘You wacko, go back to North Korea.'"

DeTrani stepped down as a senior advisor to the Director of National Intelligence in May 2012, ending more than three decades in government, the bulk of the time at the CIA.

His speech will be followed by several panels led by critics of government surveillance. The American Civil Liberties Union is holding a Friday afternoon session on "NSA surveillance and more." Representatives of the Electronic Frontier Foundation, a group that has filed lawsuits against the NSA over surveillance programs, will review "the year in digital civil liberties."

Elder, who is currently an engineering professor at George Mason University, plans to talk about applying lessons from military operations to protecting computer networks.

He said that while he knows nothing more about the Snowden case than what he has read in the paper, he expects the issue will come up. "I expect there to be some tension," he said.