Cowrie Research

whirlpool

3 min read

Whirlpool

  • Name: Whirlpool
  • URL: https://samouraiwallet.com/whirlpool
  • Category: Bitcoin CoinJoin coordinator / equal-denomination remix privacy infrastructure
  • Tags: bitcoin-ecosystem
  • Summary: Whirlpool is the stricter coordinator-run branch: equal-denomination pools, repeated remixing, and a lot of post-mix discipline. Not fancy, just legible. Privacy here depends on standardized pools, coordinator policy, remix cadence, and users not undoing the work later. That makes it a useful baseline beneath Wasabi’s variable-amount path and beside JoinMarket’s market design.
  • What it does:
    • Coordinates non-custodial Bitcoin CoinJoin transactions where participants sign locally and the coordinator only organizes the round and assembles the final transaction
    • Uses common-denomination CoinJoin structure so equal-value non-change outputs are difficult to map back to specific inputs by amount analysis
    • Encourages repeated smaller remix cycles rather than a single large join, with the reference materials framing anonymity growth as compounding over multiple cycles
    • Separates user funds into pre-mix and post-mix wallet contexts, with the post-mix side requiring stricter coin-selection and spending discipline to avoid re-linking mixed outputs later
    • Ships as a modular stack with server, client, protocol, CLI, GUI, REST, and mobile-oriented integrations rather than a single wallet-only implementation
  • Key claims:
    • The Whirlpool README explicitly frames the system as a fully modular CoinJoin implementation built on a heavily modified fork of ZeroLink rather than as a generic mixing wallet feature.
    • The ZeroLink-derived theory matters because it exposes the real design split: pre-mix wallet preparation, Chaumian-style coordinator-mediated CoinJoin rounds, and a post-mix wallet that must avoid ordinary wallet behaviors which would recombine mixed outputs and leak links again.
    • Whirlpool’s main reusable mechanism is equal-denomination remixing. The theory docs stress that Bitcoin mixing needs common denominations to resist amount analysis, while the README emphasizes many smaller cycles instead of one large cycle.
    • The coordinator is a real control surface, but a narrow one. Official materials repeatedly stress that Whirlpool is non-custodial: users sign locally, the coordinator cannot spend funds, and its role is to pass messages, match participants, and assemble transactions.
    • Whirlpool belongs in the corpus because it is the clean lower bound for coordinator-run CoinJoin after ZeroLink: a blinded coordinator, standardized pools, remix loops, and wallet hygiene doing most of the real work.
    • The strongest caveat is that Whirlpool’s privacy story depends heavily on user and wallet behavior after the round. The theory docs are explicit that poor post-mix wallet behavior can re-establish links across transaction chains even if the CoinJoin round itself was sound.
  • Whitepaper: No standalone whitepaper was reviewed for this entry. The canonical materials for this pass were the official Whirlpool pages plus the Samourai Whirlpool README, theory, and architecture notes collected in ../whitepapers/whirlpool-primary-sources-2026-05-15.md.
  • Sources:

Internal linkages

Control surface

  • The leverage sits in pool denomination policy, coordinator admission and round availability, remix cadence, and the post-mix wallet rules that decide whether users preserve or destroy the privacy they bought.

  • Treat Whirlpool as the equal-pool coordinator baseline, not as a broad Bitcoin privacy stack.

  • Last reviewed: 2026-06-10 UTC

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