Ethereum coin mixer Tornado Cash is now back on software hosting website GitHub.
The U.S. Department of the Treasury’s Office of Foreign Assets Control (OFAC) last month blacklisted Tornado Cash, which allows users to anonymously send and receive Ethereum. American citizens are now banned from interacting with the app, which pools together transactions to obscure their origins.
GitHub, a website which allows developers to share code, removed the tool’s code from its platform within hours of the OFAC announcement.
But Ethereum developers today announced that the tool’s original code was back on the popular site.
Decrypt confirmed that the Tornado Cash code was available to download but GitHub had not explained why it put it back up by the time this story was published.
Ethereum core developer Preston Van Loon announced the news on Twitter. He previously said that “code is speech and free speech is a constitutional right worth protecting.”
The Treasury Department last month said it blacklisted Tornado Cash because criminals—including North Korean state-sponsored hacking group Lazarus Group—were using it to launder money.
According to the feds, over $7 billion-worth of dirty digital cash passed through the app since its creation in 2019. But this number has been disputed—blockchain data company Elliptic said in a report that of the $7.6 billion that passed through the app, only $1.5 billion was from illegal activity.
Politicians criticized the ban and a John Hopkins University professor posted an “archival fork” of Tornado Cash’s source code to GitHub for research purposes.
An anonymous troll even went as far to send celebrities Ethereum from a Tornado Cash wallet soon after the blacklisting. The government later said it would “not prioritize enforcement” against those who had received “unsolicited and nominal” amounts of tainted crypto.
And this month, Coinbase, the biggest cryptocurrency exchange in the U.S., funded a lawsuit against the U.S. Department of Treasury for the ban.
Tornado Cash is one of many “coin mixers,” apps which anonymize crypto transactions. Such tools are popular with those who want privacy using digital assets—like someone sending funds to support a cause in Ukraine, for example.
Many cryptocurrencies, like Bitcoin and Ethereum, are pseudonymous but not anonymous—no one’s identity is recorded on the blockchain but every transaction is.
Tornado Cash is used for transactions on Ethereum, the second-biggest cryptocurrency by market cap.
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