Back in 2016, six people played a key role in the creation of a cryptocurrency called Zcash. One of the six participants, who operated online under the pseudonym John Dobbertin, remained unknown—until now.

Edward Snowden, the former National Security Agency consultant and notable whistleblower, revealed himself to be Dobbertin in a leaked video from Zcash Media, a group making educational videos about Zcash.

“I saw [Zcash] being worked on by a number of trusted academic cryptographers and I thought it was a very interesting project,” Snowden said in the video, which was first reported by Forbes.

Zcash is known as a privacy coin, because it uses zero-knowledge proofs, or cryptography that hides details—including addresses, amounts and other data—of cryptocurrency transactions. Zero-knowledge proofs allow Zcash transactions to be validated on its blockchain while keeping most aspects of the transaction invisible to the public.

This is different from Bitcoin, for example, where addresses, amounts, and other details of transactions are openly documented on its blockchain.

“Bitcoin quite famously is an open ledger,” said Snowden in the video. He was charged with espionage by the U.S. in 2013 and granted asylum in Russia. “The problem with that is you can't have truly free trade unless you have private trade. And you can't have a free society without free trade.”

In 2016, Snowden agreed to participate in what’s known as “the ceremony,” which created the Zcash blockchain’s so-called “trusted setup,” or the parameters required to create zero-knowledge proofs for Zcash’s private transactions. The ceremony has been talked about within the crypto community for years like a sort of folklore, although it was not known until now that Snowden was part of it.

During the ceremony, the private key, or random assortment of letters and numbers that acts as a sort of password needed to create Zcash coins, was split in slivers among the six participants involved—including Snowden. Other partial key holders include CoinCenter director of research Peter Van Valkenburgh and Bitcoin core developer Peter Todd, among others. The six participants were then trusted to destroy their part of the key. However, if just one participant effectively destroyed their part of the key, the network would be safe.

If a bad actor got ahold of the entire key sequence, they could create counterfeit Zcash coins. That’s why this ceremony to assign parts of the key, with a promise to destroy it, was so important.

“When it came to this concept, that they needed many people…cooperating in the hopes that just one of them might not be compromised…and that was necessary for the ceremony to succeed, I was happy to say ‘Sure, I'll help,’” Snowden said.

This story was originally featured on Fortune.com