"If we start using encrypted communication services, suddenly it becomes too expensive for the NSA," he said. "Encryption technology, even if imperfect, has the potential to raise the cost of surveillance to the point that it no longer becomes economically feasible for the government to spy on everyone."
And according to Snowden, the government is indeed doing just that right now. "The interpretation of the Constitution had been changed in secret from 'No unreasonable searches and seizures' to, 'Hey, any seizure is fine; just don't search it,'" he said. "And that's something the public ought to know about."
Elsewhere during his question-and-answer session, Snowden -- speaking in front of a green screen digitally altered to display Article 1 of the US Constitution -- said he would "absolutely" disclose documents all over again, even though his actions thus far have branded him a fugitive and traitor by many.
"I took an oath to support and defend the Constitution and I saw that the Constitution was being violated on a massive scale," he said.
Snowden and Soghoian were joined by Ben Wizner, an ACLU attorney who has personally advised the former contractor with legal assistance since he became stuck near Moscow last year. Greenwald, the journalist who first reported on Snowden's leaks, is scheduled to speak remotely at SXSW Interactive later Monday afternoon.
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