H33-74 on Zcash

How H33-74 anchors to Zcash

Each anchor is a Zcash transaction that commits to a receipt's cryptographic identity (or to a batched commitment covering many receipts). The anchor lives in Zcash's canonical ledger and is independently verifiable via any Zcash block explorer.

Anchor mechanism on Zcash

H33-74 anchors to Zcash by embedding the receipt's commitment in shielded transaction memos. The anchor record itself can be shielded so that the existence of the anchor is not visible to third parties without the viewing key. Selective disclosure allows specific parties (regulators, auditors, counterparties) to verify the anchor while keeping it opaque to others.

Chain parameters

What an H33-74 anchor record contains

• The 32-byte commitment from the receipt (or a Merkle root if batched).
• Sufficient on-chain bytes for a third party to verify the commitment matches the receipt.
• A timestamp from the Zcash block, providing independent proof that the receipt existed by no later than that block.

What it does not contain: sensitive payload data. The receipt's content lives off-chain. The anchor only commits to its existence and identity.

When Zcash is the right anchor

Zcash is the right anchor when the existence of the anchor record itself needs to remain confidential, when regulated parties need selective disclosure rather than universal transparency, and when the operator wants privacy-preserving notarization for sensitive operational evidence. Particularly appropriate for compliance evidence in regulated industries where the fact that a compliance event occurred is itself sensitive.

The portability story

A receipt anchored on Zcash can also be anchored on Bitcoin, Ethereum, Solana, Polygon zkEVM, Zcash, or any other chain H33-74 supports. The anchors are independent. Adding more anchors does not change the receipt. Removing one anchor (or having one chain become unavailable) does not invalidate the others.

If Zcash ever becomes inappropriate for an operator's use case (regulatory, performance, security, cost), the operator adds an anchor on a different chain and continues operating. The historical evidence does not have to migrate, because it was never bound to Zcash.

Verifying a Zcash anchor

A third-party verifier needs the H33-74 receipt, the Zcash anchor transaction (or its hash), and the open-source H33 verifier. From those inputs:

• The verifier checks the three post-quantum signatures over the receipt (ML-DSA-65, FALCON-512, SLH-DSA-128f).
• The verifier checks that the Zcash anchor transaction commits to the receipt's identity.
• The verifier reads the Zcash block timestamp to establish independent existence-time.

None of those steps depends on H33's infrastructure. The verifier is open-source and the chain is public.

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