Ethereum mixer Tornado Cash completes its trusted set-up ceremony

Tornado Cash, an Ethereum-based mixer that uses zero-knowledge proofs, has completed its trusted setup ceremony, taking a key step towards becoming "fully trustless."

The non-custodial service uses zk-SNARK technology and third-party relayers to hide the association between a sender address and a recipient address, making it possible for users to withdraw funds anonymously.

Systems that use zk-SNARKs require a trusted setup, an elaborate process that relies on multi-party computation to generate a crucial pair of cryptographic keys. Trusted setups are vulnerable to manipulation, but an attacker would have to compromise every participant in order to undermine the system's privacy guarantees. So, in theory, the greater number of participants, the more secure the process.

The most famous trusted setup ceremonies in the crypto space thus far have been Zcash's. In October 2016, Zcash generated its first-ever set of "public parameters" via a ceremony that involved six participants. Then, in 2018 it conducted another ceremony as part of its Sapling upgrade. That one involved 87 participants. The Tornado Cash team says its setup had a total of 1,114 "contributions," making it "by far the largest" to date.

Tornado Cash has been up and running since August of last year.  In previous versions, the participants in the trusted setup had been only the project members.

In March, The Block Research reported that it had already seen $4.4 million in deposits.

Now that the trusted setup is over, the developer team plans to "ensure that everything works as intended" before adding some finishing touches to the system "so that no one will ever be able to modify it," according to a blog post.