Edward Snowden — the ex-government contractor who exposed the NSA’s efforts to spy on the web’s most popular services — offers a simple answer to this sweeping online surveillance campaign. The way to combat NSA eavesdropping, he says, is to encrypt data as it moves across the wire.

That’s what he told the tech heads at the South by Southwest conference in Austin, Texas last week, appearing by way of a video feed streamed across the net from Russia, where he’s been granted temporary asylum from the U.S. government. Properly implemented, he explained, today’s encryption techniques work: The NSA has no way of cracking them. The onus is on the tech world to actually use them. “You guys who are in the room now are all the firefighters,” he said. “And we need you to help fix this.”

The good news is that the giants of the net — including Google and Microsoft — are already working to encrypt data, not only as it moves across the public internet but as it travels through private lines that run between the massive data centers that underpin their many web services. According to leaked government documents, the NSA has ways of tapping these lines, opening a backdoor to the internet that even those at the heart of the tech world hadn’t thought about. If the Googles and the Microsofts encrypt the data moving between their computing facilities, they can go a long way towards answering Snowden’s call to arms.

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