Privacy protection tool inventory: What other mixers are available besides Tornado?

The U.S. Department of the Treasury’s sanctions against Tornado.Cash have sparked deep reflections within the blockchain industry regarding the compliance of privacy technologies. As users, we need to understand which mixers and privacy solutions, besides Tornado, can meet reasonable privacy protection needs.

Why Do We Need Mixers?

The Transparency Dilemma of Blockchain

Bitcoin and Ethereum, as public ledgers, record all transactions on-chain. Once your wallet address is identified, every transaction in your history can potentially be traced. This complete transparency is not suitable for certain scenarios—such as businesses needing to protect sensitive commercial data or individuals seeking to safeguard financial privacy.

Core Principles of Mixers

Mixers operate with a straightforward mechanism: by pooling funds from multiple users and redistributing them to different addresses and amounts, they make it difficult for external observers to track the true flow of funds. The link between sender and receiver is broken, making transactions genuinely anonymous.

Two Types of Mixing Modes

Mixers are divided into centralized and decentralized types. Centralized mixers require trust in the operator, while decentralized mixers (like Tornado.Cash) execute automatically via smart contracts, without relying on any intermediary. The latter are more favored by users because they eliminate the need to trust a third party.

Controversies Behind the Sanctions

In August 2022, the U.S. Treasury Department added Tornado.Cash to the OFAC sanctions list, citing that the protocol has been used since 2019 to launder over $7 billion in cryptocurrency. Officially cited cases include the Wormhole bridge attack of $375 million, the Ronin bridge attack of $620 million, and other major security incidents.

Supporters argue that privacy technology itself is a neutral tool, and the key lies in the user’s intent. Opponents warn that privacy tech can be abused for illegal activities, complicating law enforcement efforts.

Alternative Mixing Tools Beyond Tornado

CoinMixer: An Established BTC Mixer

Operating since 2017, CoinMixer is a veteran mixing protocol that currently manages over $1.2 million worth of Bitcoin. Unlike mixers that require waiting for enough participants, CoinMixer, with ample funds, can achieve near real-time mixing.

Its fee structure is 0.5% per transaction plus a base fee of 0.0005 BTC. Larger transactions may receive discounted rates. After Tornado was sanctioned, CoinMixer stated it has never recorded user activity nor received any government orders.

Umbra: Ethereum Privacy Transfer Protocol

Umbra enables users to perform untraceable transfers on Ethereum. Its clever design allows the recipient to create a temporary privacy address (controlled by the original private key, no backup needed). The sender only needs to input the recipient’s real address; Umbra automatically recognizes the privacy address and completes the transfer. Afterward, funds can be moved to a secure address to ensure full privacy.

The protocol supports Ethereum, Polygon, Optimism, Arbitrum networks, and mainstream tokens like ETH, USDC, USDT, DAI.

CoinJoin: A Classic Bitcoin Privacy Solution

As one of the oldest mixers, CoinJoin was developed for Bitcoin and Bitcoin Cash. Its principle involves multiple parties jointly signing a smart contract to mix their transactions in a single multi-party transfer, making it difficult for tracers to distinguish fund flows. The code is fully open-source, with no logs or tracking, embodying the philosophy that “financial privacy is a human right.”

ChipMixer: A Flexible Mixing Solution

ChipMixer operates differently: users send Bitcoin to its address and receive corresponding “Chips” (which are actually private keys). These can be imported into any wallet, giving users control over when to spend them. Since these bitcoins are deposited before being spent, the on-chain link between sent and received coins is obscured. Users can also split, merge, or transfer Chips, further enhancing anonymity.

Status of Privacy Coin Projects

Besides using mixers, users can also choose cryptocurrencies with built-in privacy features.

Monero (XMR): Three-Layer Privacy Protection

Monero employs ring signatures to hide the sender, stealth addresses to conceal the receiver, and ring confidential transactions (RingCT) to obscure transaction amounts. The combination of these three layers provides industry-recognized strong privacy protection.

Zcash (ZEC): Zero-Knowledge Proofs

Zcash uses zero-knowledge proofs to allow transaction validation without revealing other information. It offers two address types: transparent addresses (t-addresses), which provide the same transparency as Bitcoin, and shielded addresses (z-addresses), which fully conceal transaction amounts and participants.

Dash: Three Transaction Modes

Dash offers standard transfers, InstantSend, and PrivateSend modes. Its unique “masternodes” coordinate multiple mixing requests to facilitate coin mixing. However, compared to the first two, Dash’s privacy features involve centralized components, making its privacy slightly less robust.

Future Risks Facing Privacy Projects

Following Tornado’s sanctions, the market generally worries that privacy-focused projects like Monero and Zcash may also face increased regulatory pressure. These projects need to balance privacy protection with compliance requirements.

For ordinary users, understanding the features of these tools and projects, and choosing carefully based on individual needs, is the best way to navigate uncertainties.