Tornado Cash is a decentralized, non-custodial cryptocurrency mixer built on Ethereum and other EVM-compatible blockchains. Launched in 2019, it uses smart contracts and zero-knowledge proofs (specifically zk-SNARKs) to break the on-chain link between sender and receiver, allowing users to deposit crypto and later withdraw it to a different address with their identity and transaction history concealed. It supports various tokens, including ETH, DAI, USDC, USDT, and WBTC, and operates autonomously—no individual or entity controls the funds or can alter the protocol once deployed.
Users deposit cryptocurrency into a Tornado Cash smart contract, which issues a cryptographic note. This note can later be used to withdraw the same amount to another address, with zk-SNARKs ensuring the withdrawal cannot be linked to the original deposit. The protocol’s design ensures privacy by pooling deposits and delinking withdrawals, making it extremely difficult to trace funds through blockchain analysis.