A former computer hacker who styles himself as a corruption-buster has been charged with flouting U.S. law to give North Korea advice on evading American sanctions by using cryptocurrency.

Virgil Griffith, 36, was once dubbed an “internet man of mystery” by The New York Times. He has an Ph.D from the California Institute of Technology and works for the Ethereum Foundation, which produces a digital currency token that’s a rival to Bitcoin.

According to a criminal complaint filed in federal court in Manhattan, Griffith sought permission from U.S. authorities to attend the Pyongyang Blockchain and Cryptocurrency Conference in North Korea in April.

He was denied but allegedly went anyway and recruited others to travel to North Korea to aid the government there, as well.

The Justice Department alleges that, while giving a presentation titled “Blockchain and Peace,” Griffith described how North Korea could “launder money and evade sanctions” and “use these technologies to achieve independence from the global banking system.”

Griffith—an American citizen who has been living in Singapore—hoped the cryptocurrency made by his own company, unnamed in the complaint, would be North Korea’s choice, the feds charged.

The North Korean regime allegedly approved his talk. Governments across the world, including the United States, have largely shut the country out over human rights abuses and efforts to build nuclear weapons.

Prior the conference, Griffith allegedly exchanged messages with an associate about North Korea’s potential use cryptocurrency that appear to demonstrate he knew the illegality of what he was doing.

“I need to send 1 unit of [Cryptocurrency-1, which belonged to Griffith’s company] between North and South Korea,” he wrote.

“Isn’t that avoiding sanctions,” his associate asked.

“It is,” Griffith wrote, according to the complaint.

He was arrested at Los Angeles International Airport Thanksgiving Day and arraigned Friday. He faces 20 years in prison if convicted.

An Alabama native, Griffith reportedly became a hacker in college then invented WikiScanner, which exposes anonymous edits to Wikipedia entries, after graduation.

A website that appears to belong to him, but which has not been updated since 2016, says: “My goals are to expose corruption, curb abuses of power, and with ‘gloves off’ ensure the digital age never becomes a digital dystopia.”

The magazine, 2600: The Hacker Quarterly called Griffith’s arrest “an attack on all of us.”

“Yes, we are biased because we know this person and his motivations, which align with hacker culture: explaining tech, visiting weird places, & being honest. These are not crimes in our eyes,” it said in a tweet.

2600 editor Emmanuel Goldstein said in a tweet that Griffith did not believe he had done anything wrong.

“Crap. He insisted on going to the @FBI and telling the truth w/o a lawyer. I kept warning him it was a trap. What's ironic is that afterwards, he was convinced they totally got where he was coming from,” he wrote.

CORRECTION, 12:53AM, 12/02/19: The spelling of the Ethereum Foundation has been corrected and updated.