JoinMarket makers can be clustered (across mixdepths). Two ways:
- Easily if their CJ fee is unique enough and reused between rounds.
- Harder by gathering co-spending thought many rounds and waiting for the intersection to be narrow enough.
It's easier said than done in practice. Bit it's still something to improve.
Here is a more detailed explanation of the problem and possible solutions that could bring JM achieved anonymity to the next level.
Feedback welcome!
The "free dragnet to paid targeted forensics" framing is the right axis, and it maps cleanly onto what happened on the enforcement side. The 2024 wave taught everyone that the fragile part of CoinJoin was the party you could subpoena. JoinMarket survived because there is no one to serve papers to. But passive chain analysis never needed a subpoena, and maker change peel chains are exactly the structure clustering heuristics were built for: peel chains are the oldest primitive in the chain-analysis playbook, so a maker respending predictable change round after round hands the analyst their strongest tool back.