Zerolink
ZeroLink is a 2017 fungibility framework from Adam Ficsor (nopara73) that turned a loose set of privacy ideas into a concrete wallet architecture. Instead of treating CoinJoin as a single transaction trick, ZeroLink defines coordinator interaction, credential handling, fee logic, output registration, and post-mix wallet behavior. Its Github repository was archived in 2020, but is still accessible.[1]
At a high level, ZeroLink is built on three practical principles that work together. If one part is missing, the privacy benefit drops quickly in real-world usage.
- CoinJoin coordination
- Wallet hygine
- Toxic change policy
Zerolink's coinjoin involves users registering inputs with a coordinator, obtaining blind-signed credentials, and redeeming them for anonymized outputs. It enforces mandatory fresh addresses, randomized fees, and separate change outputs. Wallets automatically quarantine change and avoid merging it back into mixed UTXOs.