Summary: ZeroLink is the old baseline for Chaumian CoinJoin wallet discipline: pre-mix wallet, post-mix wallet, blind-signature coordinator, common denominations, Tor. Mostly obsolete, but still useful because later coordinator-run systems mostly read as upgrades, relaxations, or repackagings of this frame.
What it does:
Defines a wallet privacy framework that splits Bitcoin funds into pre-mix and post-mix contexts with different privacy requirements
Specifies Chaumian CoinJoin as its preferred mixing technique, using a coordinator (or Tumbler) that signs blinded outputs, later accepts unblinded outputs over a different anonymity-network identity, and then assembles a CoinJoin for users to sign
Treats common-denomination outputs and multi-round mixing as necessary defenses against amount analysis and transaction-chain relinking
Requires anonymity-network use, especially Tor-hidden-service-style communication, for both mixing and transaction broadcasting rather than treating network privacy as an optional extra
Frames wallet coin selection, indexing, balance retrieval, and post-mix spending behavior as first-class parts of the privacy system rather than ordinary wallet implementation details
Key claims:
ZeroLink’s main contribution is conceptual scope: it explicitly says privacy failure can happen across transaction chains and at the network layer, so the protocol surface has to include wallet behavior before and after the CoinJoin round, not only the round itself.
The README defines a centralized-but-untrusted Chaumian CoinJoin coordinator that can organize rounds and verify signed outputs without being able to steal coins or directly violate anonymity under the intended flow.
The framework is explicit that equal denominations matter. Without common-denomination outputs, simple amount analysis can relink flows, so ZeroLink treats standardized outputs and repeated rounds as structural privacy requirements.
ZeroLink also makes the privacy is teamwork claim unusually concrete: one participant’s bad network or wallet setup can shrink everyone else’s effective anonymity set, so compliant wallet defaults matter as much as the cryptographic round.
The project now calls itself obsolete in favor of WabiSabi, which makes it more useful, not less, for the corpus: it is a clear historical baseline for comparing Whirlpool-style equal-pool remixing against WabiSabi’s variable-amount anonymous-credential design.
ZeroLink belongs in the library because it gives the Bitcoin privacy section a protocol-and-wallet baseline beneath later branded implementations, especially for pre-mix/post-mix wallet separation, coordinator trust boundaries, and transaction-chain privacy framing.
Whitepaper: No standalone academic whitepaper was surfaced beyond the project’s own README / framework text and the launch post. The strongest primary materials for this pass were the archived GitHub repository README and nopara73’s introduction post; see ../whitepapers/zerolink-primary-sources-2026-05-15.md.