zkCoins

• Name: zkCoins
• URL: https://docs.zkcoins.app/
• Category: bitcoin client-side validation / shielded transaction infrastructure / proof-carrying-data payments
• Tags: bitcoin-ecosystem
• Summary: zkCoins is a Shielded CSV implementation track, not some new Bitcoin base layer. Useful note because it makes the actual control surface legible: sender-side proof generation, offchain proof handoff, receiver-side verification, and Bitcoin reduced mostly to nullifier ordering. Serious prototype, not finished protocol.
• What it does:
  • Builds a wallet around Shielded CSV, a client-side-validation payment protocol for Bitcoin that keeps validation and transaction history offchain between participants
  • Uses proof-carrying data so each received coin comes with a constant-size zero-knowledge proof of valid ancestry rather than a history that grows with every prior hop
  • Posts only nullifier-related data to Bitcoin so the base chain mainly serves as a double-spend-prevention ordering layer instead of a full transaction-replay layer
  • Aims to preserve sender, receiver, amount, and graph privacy by revealing only that a spend occurred, not the underlying transfer details
  • Reuses Bitcoin directly without proposing a soft fork, sidechain, new asset, or separate consensus system
  • Packages the protocol into a deployable wallet/server stack derived from the earlier ZeroSync prototype
• Key claims:
  • The docs make the Shielded CSV flow concrete instead of leaving it as paper architecture: sender proof generation, offchain proof handoff, publisher-side nullifier posting, receiver-side verification, and Bitcoin as a narrow anti-double-spend base layer.
  • The real mechanism is proof-carrying transaction validity. Each coin carries a constant-size proof of valid ancestry instead of dragging growing history along forever.
  • The small-onchain-footprint framing matters because zkCoins is trying to shrink Bitcoin’s role to opaque nullifier publication while moving most semantic validation offchain.
  • The implementation is still behind the full paper. PROTOCOL_STATUS.md says the current stack does not yet implement the full nullifier system, Schnorr half-aggregation, conditional NAV, trustless publisher fees, or scanner-side aggregate-signature verification, so read it as a serious prototype path, not finished protocol.
• Whitepaper: zkCoins does not appear to publish a separate standalone wallet whitepaper. Its canonical protocol paper is Shielded CSV, collected alongside project materials in ../whitepapers/zkcoins-primary-sources-2026-05-13.md.
• Sources:
  • https://docs.zkcoins.app/
  • https://docs.zkcoins.app/protocol/
  • https://github.com/zk-coins/docs
  • https://github.com/zk-coins/research
  • https://raw.githubusercontent.com/zk-coins/research/develop/PROTOCOL_STATUS.md
  • https://eprint.iacr.org/2025/068
  • https://shieldedcsv.org/

Internal linkages

• Keep the budget short.

• Best protocol baseline: shielded-csv.

• Best broader client-side-validation contrast: rgb.

• Best adjacent Bitcoin state-offload contrast: spark.

• Last reviewed: 2026-06-02 UTC