Community Audit Report SwissCoordinator.app (2025)

Version: 1.0 (public release) Date: October 1, 2025 Authors: Wasabi Community Audit Group (WCAG) License: CC-BY-SA 4.0 1) Executive Summary Objective. The goal here is to assess SwissCoordinator.app, which serves as an independent WabiSabi CoinJoin coordinator working with Wasabi Wallet, based on criteria like privacy, correctness, reliability, and transparency. Window. The evaluation took place from September 10 to 30, 2025, spanning across EU, US, and APAC time zones for a total of 21 days. Sample. Out of 304 attempted rounds, 298 were completed successfully, giving a success rate of 98.0%. There were 6 failures (3 were due to blame rounds and 3 were timeouts during input registration). Key findings. Protocol adherence: The message flows and phases of the rounds were in line with expectations outlined for WabiSabi (input registration → connection confirmation → output registration → signing). No unexpected fields or fingerprinting artifacts were found during our review. Privacy assessment: We didn’t find any signs of UTXO blacklisting or prioritizing clients during testing; there were no persistent identifiers at the application level, and traffic was routed through Tor. Fees: Throughout all the observed rounds, the coordinator fee was kept at 0.00%. Only miner fees applied, with a median of 14 sat/vB (interquartile range of 9 to 21). Performance: The median round lasted 22 minutes (mean was 24.6; p95 was 38). The median number of participants per round was 60 (IQR 50-68), and the median anonymity set per class was 46 (IQR 38-53). Transparency: The canary and transparency pages stayed consistent throughout the audit period. The operator provided a build hash and a PGP-signed attestation upon request, and the signature verification was successful. Conclusion. Given the scope and limitations of our audit, SwissCoordinator.app acted as a privacy-focused, protocol-compliant WabiSabi coordinator.