SAN FRANCISCO (CBS SF) — If earth and alien worlds are trying to communicate with one another, encryption might be getting in the way.

That’s what fugitive National Security Administration ‘leaker’ Edward Snowden told astrophysicist Neil de Grasse Tyson last week during a surprise appearance on the podcast StarTalk.

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Snowden spoke via a remote-controlled robotic telepresence from Russia. The former NSA contractor has been living there in asylum ever since he leaked classified documents revealing the U.S. government was spying on Americans and foreign allies using phone records.

Astrophysicist Neil deGrasse Tyson . (Photo by Mike Lawrie/Getty Images)

Astrophysicist Neil deGrasse Tyson . (Photo by Mike Lawrie/Getty Images)

When the conversation turned to privacy and cybersecurity, Snowden told Tyson an evolved alien civilizations would probably protect their communications through encryption, just as earthlings do. He posits that could be the reason we’ve never heard from them.

Sophisticated data encryption may isolate our world from the rest of the universe, and vice-versa.

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“So if you have an an alien civilization trying to listen for other civilizations or our civilization trying to listen for aliens, there’s only one small period in the development of their society when all their communication will be sent via the most primitive and most unprotected means.”

“What we are hearing, that’s actually an alien television show or, you know, a phone call … is indistinguishable to us from cosmic microwave background radiation,” said Snowden.

LISTEN: A Conversation with Edward Snowden

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Snowden has made remote appearances before via his remote-controlled BeamPro robot, designed by Palo Alto-based Suitable Technologies. The so-called ‘Snowdenbot’ appeared at a TED talk in 2014 and maintains a permanent presence in Snowden’s ACLU lawyer’s office.