H33-74 on Bitcoin

Bitcoin is one of H33-74's anchor surfaces, not its foundation. The receipt exists before the Bitcoin anchor and remains valid if the Bitcoin anchor is later supplemented or replaced on another chain. Bitcoin provides one independent notarization. H33-74 receipts can carry many.

How H33-74 anchors to Bitcoin

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

Anchor mechanism on Bitcoin

H33-74 anchors to Bitcoin primarily via Taproot (BIP-341 P2TR), which provides witness-discounted commitment space and the strongest economic security for long-horizon evidence. OP_RETURN is supported as a fallback for tooling that does not yet handle Taproot.

Chain parameters

Chain

Bitcoin

Finality

6 confirmations (~60 minutes) for high-value anchors; 1 confirmation (~10 min) acceptable for routine notarization.

Anchor cost

One Bitcoin transaction per anchor batch. With Taproot's witness discount, batched anchors are typically a few thousand satoshis (a few dollars) regardless of how many receipts the batch covers.

Explorer

mempool.space

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 Bitcoin 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 Bitcoin is the right anchor

Bitcoin is the right anchor when independent notarization needs to survive the longest possible time horizon, when economic security of the notarization matters more than per-anchor cost, and when audit-grade durability is required for regulatory or institutional use. Bitcoin's settlement assurance is the highest available; it makes the strongest single-chain anchor for evidence that must last decades.

The portability story

A receipt anchored on Bitcoin 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 Bitcoin 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 Bitcoin.

Verifying a Bitcoin anchor

A third-party verifier needs the H33-74 receipt, the Bitcoin 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 Bitcoin anchor transaction commits to the receipt's identity.
The verifier reads the Bitcoin 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.

See H33-74 on other chains

The same receipts that anchor to Bitcoin can anchor to any of the others.

One Receipt. Multiple Chains. H33-74 Overview