What Is CoinJoin?
CoinJoin is a privacy-enhancing technique where multiple Bitcoin users combine their transactions into a single collaborative transaction. This breaks the common input ownership heuristic, making it difficult for observers to determine which inputs fund which outputs, thereby improving transaction privacy.
Key Aspects
Privacy Enhancement
CoinJoin significantly improves privacy by obfuscating transaction trails on the blockchain. Chain analysis becomes exponentially more difficult as the number of participants increases.
Coordination Methods
CoinJoin can be coordinated through centralized coordinators, decentralized protocols, or peer-to-peer arrangements. PayJoin is a simpler variant that works between just two parties.
Popular implementations include Wasabi Wallet and Samourai Whirlpool (though the latter faced legal challenges). CoinJoin transactions are completely valid Bitcoin transactions and don't require any protocol changes. However, they're larger and require higher fees due to multiple participants.
Quick Facts
- •Breaks the common input ownership heuristic
- •No trusted third party required
- •Implemented in Wasabi Wallet, Samourai Wallet, and JoinMarket