Also called: EAS, attestation
In plain words
The Ethereum Attestation Service is shared, open infrastructure for making attestations: structured statements that an address signs and records on-chain (or off-chain). Each attestation follows a registered schema identified by a schema UID, so anyone can decode what it says. It records who attested, when (the block timestamp) and the data. EAS is deployed on Ethereum and on many layer-2 networks, Base among them.
It's a way to publish a small, verifiable fact without deploying and auditing a custom smart contract for it.
How QED Proof uses it
QED Proof's anchor is an EAS attestation whose data decodes to the log's identity, size and root: (log_id, tree_size, root_hash, …). The attester addresses and the schema UID are published in poaw-keys.json, so a checker knows which attestations are genuinely ours. To check an anchor, a checker:
- fetches the attestation from the chain named in
proof.anchor; - confirms it comes from a published attester address;
- decodes it with the published schema;
- confirms it matches the receipt's log and root (or verifies an RFC 6962 consistency proof between the two tree sizes).
The attestation's block timestamp is the receipt's proven-by time. Anchoring runs today on Base Sepolia; Base mainnet is next.
Example
The receipt spec records the scheme explicitly ("scheme": "eas"), so a future anchoring method can sit beside it without changing what existing receipts mean.