These repositories contain an archival fork of the Tornado Cash and Tornado Cash Nova source code base. They are maintained on Github by Matthew D. Green of Johns Hopkins for teaching and research purposes.
Tornado Cash and Tornado Nova are open-source coin mixing tools that were developed by an independent team of software developers and deployed onto Ethereum and several other blockchains. On August 8, 2022 the Office of Foreign Assets Control (OFAC), a division of the US Treasury, declared “Tornado Cash” and “Tornado Cash Nova” to be Specially Designated Nationals (SDNs): the result was to effectively sanction the Tornado Cash organization, its software development repositories, and the main smart contract deployment on Ethereum.
This move to sanction Tornado Cash represents the first instance in which the US government has applied economic sanctions to an open source software project. As a result of this announcement, several cryptocurrency exchanges have banned users who interact with the Tornado Cash smart contract address on Ethereum. Within hours of the OFAC announcement, Github shut down the user accounts of all known Tornado Cash developers and removed the source code repositories owned by Tornado’s Github organization.
While Github succeeded in removing the original copies of all Tornado source code repositories, they did not remove all “forks” of the code made by GitHub users. Several of these forks were recently collected and (further) forked by contributors to the tornadocash-community organization. Those folks did the hard work. The current repository is simply another fork of the repositories they collected.
If you want a copy of the code on a more durable decentralized medium, there are copies of (limited) repositories on IPFS. I certainly don’t warranty these (or any of this code), and you should carefully check hashes against the repositories on Github and in the Wayback Machine just in case: