Since first leaking sensitive NSA documents from last summer, Snowden has been holed up in Russia but was able to speak at the show by using Google Hangouts and seven proxies. Snowden's attorney Ben Wizner and ACLU technologist Chris Soghoian were also in attendance to help conduct the talk, as well as the Q&A session at the end.
In front of a 3,500-strong crowd, Snowden was particularly keen to stress that his actions had improved national security of the United States, rather than undermine it – as suggested by NSA director General Keith Alexander, while he strongly rejected accusations that his files may have found their way to intelligence agencies in Russia or China.
“That has never happened, and it is never going to happen,” he told attendees. “If suddenly the Chinese government knew everything the NSA was doing, we would notice the difference.”
He, too, was adamant that he change nothing about his situation, despite the revelations putting his life is danger, as well as preventing him from seeing his family in the U.S.
“Would I do this again? The answer is absolutely yes,” he said. “Regardless of what happens to me, this is something we had a right to know.”
“These things are improving national security, these are improving the communications not just of Americans, but everyone in the world,” Snowden added.
Calls for encryption communications
That led Snowden, who has applied for political asylum in as many as 20 countries, to stress the need for encryption, something that Soghoian and security guru Bruce Schneier championed for at B-Sides San Francisco and the RSA Conference respectively last month.
“We need to think about encryption not as this arcane black art but as a basic protection, the defence against the black arts in the digital realm,” Snowden said, before urging users to use Tor for anonymous browsing.
Soghoian agreed with this point by suggested that most ordinary folk are unlikely to embrace encryption by going full-disk encryption or SSL.
“Most people aren't going to go out and download an obscure encryption [tool],” said Soghoian. “They're going to use the tools they already have: Facebook, Google, Skype. When Google turned on [SSL for Gmail], they made passive surveillance of users' communications more difficult for agencies. We need services to be building security in. That doesn't mean that small developers can't play a role. What I want is for the next WhatsApp or Twitter to use encrypted end-to-end communications.”
NSA reforms welcomed by Snowden
There was criticism too for the likes of Google and Facebook, with speakers saying that they prioritise data collection for serving ads over data protection for users, while Snowden also urged for a reform to the way NSA collects data.
Back in January, U.S. President Obama promised an agency reform, which will, among other things, see the NSA collect data ‘two steps removed' from a phone number associated with a terrorist organisation.
Speaking at the conference, Snowden said that the agency spent too much effort harvesting communications en masse, and yet still they missed terrorists such as Tamerian Tsamaev, one of the brothers alleged to have bombed the Boston Marathon last year, and Umar Farouk Abdulmutallab – the “underwear bomber” who tried to blow up a plane bound for Detroit in 2009.
“We are monitoring everyone's communications rather than suspects' communications,” he said. “If we hadn't spent so much on mass surveillance, if we had followed traditional patterns, we might have caught him.”
Towards the end of his talk (which can be seen here on YouTube), Snowden accepted praise from Internet pioneer Sir Tim Berners-Lee, who tweeted that he was “acting profoundly in the public interest”.
Others, though, were less enamoured with his presence at the cultural festival – where WikiLeaks founder Julian Assange and Glenn Gleenwald also spoke via video link.
In an open letter to organisers, US Congressman Mike Pompeo of Kansas said that Snowden's “only apparent qualification is his willingness to steal from his own government and then flee to that beacon of first amendment freedoms, the Russia of Vladimir Putin".
Event organisers, however, defended the decision.
“I appreciate his interest in SXSW, but I've never uninvited a speaker, and so we wouldn't do this with Snowden,” SXSW interactive director Hugh Forrest told Forbes. “Our goal here is to be an open platform. I'd love to have the NSA giving a lecture.”