What is Tornado Cash, and why did it get into trouble?

Tornado Cash is designed to make transactions private, but allegations of money laundering led to US sanctions, though they were lifted in March 2025.

Tornado Cash is a decentralized, non-custodial crypto mixer designed to enhance transaction privacy on public blockchains. It uses smart contracts and zero-knowledge (ZK) proofs to conceal the onchain link between the sender and receiver of a transaction.

Launched by Roman Storm and Roman Semenov on Ethereum in 2019, Tornado Cash allows users to send and receive cryptocurrency anonymously, without exposing their wallet history. Unlike centralized mixers, Tornado Cash operates entirely onchain through immutable smart contracts, meaning no central party controls the funds. 

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