Andy Greenberg: When NSA Director Keith Alexander appeared at the Las Vegas security conference Black Hat Wednesday morning, he hoped to mend the NSA’s reputation in the eyes of thousands of the conference’s hackers and security professionals. It didn’t go exactly as planned.

Alexander was about a half hour into his talk when a 30-year-old security consultant named Jon McCoy shouted “Freedom!”

“Exactly,” responded Alexander. “We stand for freedom.”

“Bullshit!” McCoy shouted.

“Not bad,” Alexander said, as applause broke out in the crowd. “But I think what you’re saying is that in these cases, what’s the distinction, where’s the discussion and what tools do we have to stop this.”

“No, I’m saying I don’t trust you!” shouted McCoy.

“You lied to Congress. Why would people believe you’re not lying to us right now?” another voice in the crowd added.

“I haven’t lied to Congress,” Alexander responded, visibly tensing. “I do think it’s important for us to have this discussion. Because in my opinion, what you believe is what’s written in the press without looking at the facts. This is the greatest technical center of gravity in the world. I ask that you all look at those facts.”