H33-74 on Arbitrum One

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

How H33-74 anchors to Arbitrum One

H33-74 anchors to Arbitrum One via EIP-1559 calldata commitments. As an optimistic rollup, Arbitrum settlement assurance inherits from Ethereum L1 once the batch is posted to L1.

Chain parameters

Chain

Arbitrum One (chain ID 42161)

Finality

L2 soft finality in seconds; L1-inherited hard finality on Ethereum settlement (~7 days for full optimistic rollup challenge window, ~hours typical).

Anchor cost

Significantly lower than Ethereum L1 (typically 10x to 50x cheaper). Calldata cost depends on Ethereum L1 calldata pricing.

Explorer

arbiscan.io

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 Arbitrum One 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 Arbitrum One is the right anchor

Arbitrum One is the right anchor when EVM-compatible tooling is needed, when L1-grade settlement assurance is required but L1 gas costs are not, and when the operator wants the security inheritance of an optimistic rollup. Particularly appropriate for DeFi-adjacent and RWA use cases that need EVM interoperability without paying Ethereum mainnet costs.

The portability story

A receipt anchored on Arbitrum One 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 Arbitrum One 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 Arbitrum One.

Verifying a Arbitrum One anchor

A third-party verifier needs the H33-74 receipt, the Arbitrum One 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.
The verifier checks that the Arbitrum One anchor transaction commits to the receipt's identity.
The verifier reads the Arbitrum One block timestamp to establish independent existence-time.

See H33-74 on other chains

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

One Receipt. Multiple Chains. H33-74 Overview