29. Bring an EAS attestation in as a claim

An investor that an attester has already verified on the Ethereum Attestation Service (EAS) does not need a second credential. The attestation is brought in as a claim: a record on the investor's ONCHAINID that points to the attestation and names the EASClaimIssuer adapter as its issuer. The Identity Owner adds the record once the attester has attested. From then on, every asset that trusts the adapter for the topic counts it, and the adapter reads the attestation from EAS at every eligibility check.

At a glance

Triggered by	Identity Owner, after the attester has attested
Actors	Attester, Investor, Identity Owner, Platform, Issuer, Network governance
Contracts	EAS, EASClaimIssuer, the ONCHAINID of the Investor, ERC734Validator, IdentityFactory (read only), TREXRegistry (read only, for the effect)
Preconditions	The Investor has an ONCHAINID (see 02); an EASClaimIssuer is deployed for the EAS contract of the chain; in the adapter, the claim topic is bound to an EAS schema and the attester is accepted for that topic; the Identity Owner controls a CLAIM_SIGNER or CLAIM_ADDER key of the identity
Result	The Investor's identity holds a claim whose issuer is the adapter and which points to the attestation. The claim is valid for as long as the attestation is

Actors and roles

Actor	Role in this flow	What they hold
Attester	Verifies the Investor off-chain and attests on EAS. It plays the part of a Claim Issuer, through the adapter.	An address accepted by the adapter for the topic
Investor	The subject of the attestation.	An ONCHAINID
Identity Owner	The Investor in its capacity as controller of the identity. Adds the claim record.	A CLAIM_SIGNER or CLAIM_ADDER key on its identity
Platform	Reads the attestation, builds the record and prepares the call.	Whatever keys the Identity Owner has authorized
Issuer	Decides whether its asset trusts the adapter for the topic. Does not transact in this flow.	OWNER in the asset's domain
Network governance	Administers the adapter: which schema stands for which topic, and which attesters are accepted. Does not transact in this flow.	The role that administers the adapter

Sequence

Step by step

Step 1. Attest on EAS

Who: Attester

Call: attest on the EAS contract of the chain. EAS is not part of the protocol

Before the call: The Attester has verified the Investor under its own process. It knows the schema that the adapter binds to the topic: EASClaimIssuer.getSchemaForTopic(topic).

What happens: The Attester attests under that schema, with the Investor's ONCHAINID as recipient, or a wallet linked to it. EAS records the attestation and returns its UID. The attestation carries its time, its expiration time if it has one, and its data.

What changes: The attestation exists on EAS. Nothing changes in the protocol.

Step 2. Build the claim record

Who: Platform, on behalf of the Identity Owner

Call: Off-chain, using read calls

Before the call: The Platform has the UID of the attestation.

What happens: The Platform reads the attestation with getAttestation(uid) on EAS and builds a record that mirrors it.

Field	Value
topic	The claim topic the attestation stands for.
scheme, uri	How the claim is to be read, and where supporting material is.
issuer	The address of the EASClaimIssuer.
signature	The UID of the attestation, as 32 bytes.
data.issuedAt	The time of the attestation.
data.validUntil	The expiration time of the attestation. Zero when it has none.
data.metadataHash	getMetadataHash(scheme, uri), read on the ERC734Validator, the module whose address Identity.registryModule() returns.
data.payload	The data of the attestation.

It then reads EASClaimIssuer.getClaimStatus(identity, topic, signature, data), which must return Valid.

What changes: Nothing on-chain.

Step 3. Add the claim record to the identity

Who: Identity Owner (CLAIM_SIGNER or CLAIM_ADDER key of the Investor's identity)

Call: addClaim(topic, scheme, issuer, signature, data, uri), called on the Investor's ONCHAINID, with the adapter as issuer

Before the call: Step 2 returned Valid. The call is made directly on the identity by the key holder.

What the contract checks:

1. The caller holds CLAIM_SIGNER or CLAIM_ADDER on the identity. A MANAGEMENT key satisfies any purpose. Otherwise the call reverts with SenderDoesNotHaveClaimSignerKey.

2. The topic is not zero. Otherwise InvalidClaimTopic.

3. The signature, the payload and the URI are within their maximum lengths. Otherwise ClaimSignatureTooLong, ClaimPayloadTooLong or ClaimUriTooLong.

4. data.metadataHash matches the scheme and the URI. Otherwise ClaimMetadataMismatch.

5. The adapter answers that the claim is valid for this identity. Otherwise InvalidClaim. The adapter requires all of the following:

   • the topic is bound to a schema;

   • the signature is a 32-byte UID, and an attestation exists for it on EAS;

   • the attestation uses the schema bound to the topic, and its attester is accepted for the topic;

   • the record mirrors the attestation: same time, same expiration time, same data;

   • the attestation is not revoked and has not expired;

   • the recipient of the attestation is the identity itself, created by the IdentityFactory, or a wallet linked to the identity.

What changes: The claim is stored on the identity under claimId = keccak256(abi.encode(issuer, topic)). The ERC734Validator emits ClaimAdded, or ClaimChanged when the identity already held a claim from the adapter for this topic. Nothing is stored on the adapter.

Step 4. Confirm the effect

Who: Platform

Call: Off-chain, using read calls

Before the call: Step 3 is confirmed.

What happens: For each asset the Investor wants to hold, the Platform reads TREXRegistry.isVerified(address) for the Investor's addresses. The result is true when the Issuer of the asset trusts the adapter for the topic (see 04) and the other required topics of the asset are satisfied.

What changes: Nothing on-chain.

State after the flow

• getClaim(claimId) on the Investor's identity returns the record, with the adapter as issuer and the UID as signature.

• EASClaimIssuer.isClaimValid(identity, topic, signature, data) returns true, for as long as the attestation is neither revoked nor expired and the adapter keeps the schema and the attester for the topic.

• For every asset that trusts the adapter for the topic, the claim satisfies the topic for every address of the Investor's identity.

• The adapter holds no record of the claim. It answers from EAS at every call.

• An indexer has seen ClaimAdded or ClaimChanged on the ERC734Validator.

Failure modes

Symptom	Cause	Fix
getClaimStatus returns NotIssued	The topic is not bound to a schema, the attestation uses another schema, the attester is not accepted for the topic, the record does not mirror the attestation, or the recipient is neither the identity nor a wallet linked to it (step 3, check 5)	Compare the record with getAttestation(uid). Read getSchemaForTopic(topic) and getIsAttesterAllowed(topic, attester) on the adapter
getClaimStatus returns BadSignature	The signature field is not a 32-byte UID (step 3, check 5)	Pass the UID as abi.encodePacked(uid)
getClaimStatus returns Revoked or Expired	The attester revoked the attestation on EAS, or the attestation reached its expiration time (step 3, check 5)	The Attester attests again. Use the new UID
addClaim reverts with SenderDoesNotHaveClaimSignerKey	The caller holds neither CLAIM_SIGNER nor CLAIM_ADDER on the identity (step 3, check 1)	Submit with a claim key of the identity
addClaim reverts with InvalidClaimTopic	The topic is zero (step 3, check 2)	Use the claim topic the schema is bound to
addClaim reverts with ClaimSignatureTooLong, ClaimPayloadTooLong or ClaimUriTooLong	A field exceeds its maximum length (step 3, check 3)	An attestation whose data exceeds the maximum payload cannot be brought in as a claim
addClaim reverts with ClaimMetadataMismatch	data.metadataHash was computed for another scheme or URI (step 3, check 4)	Read ERC734Validator.getMetadataHash(scheme, uri) again with the values submitted
addClaim reverts with InvalidClaim	The adapter does not answer Valid (step 3, check 5)	Read getClaimStatus for the reason, as in step 2
The call is refused when sent as a user operation	addClaim requires a direct call from the key holder	Call the identity directly
addClaimTo on the adapter reverts with EASNotSupported	The adapter cannot add a claim to an identity	The Identity Owner adds the record, as in step 3
The claim is on the identity and the Investor is not eligible for an asset	The Issuer of that asset does not trust the adapter for the topic, or another required topic is not satisfied	The Issuer decides: 04
The claim was valid and no longer is	The attester revoked the attestation, the attestation expired, or the adapter no longer accepts the attester or the schema	Nothing to repair on the identity. A new attestation is brought in with this flow

Common misunderstandings

Wrong: "The adapter issues the claim."

Right: The adapter adds nothing to any identity and stores nothing. The Identity Owner adds the record. The adapter answers one question, at every check: is the attestation behind this record valid for this identity, now.

Wrong: "Once the record is on the identity, the investor stays eligible."

Right: Validity is read from EAS at every eligibility check. When the attester revokes the attestation, or when it expires, the claim stops counting from the next check, with no transaction in the protocol.

Wrong: "The record can describe the attestation in its own words."

Right: The record mirrors the attestation: its time, its expiration time and its data. The adapter refuses a record that differs, so what an identity stores is what the attester signed.

Wrong: "An attestation made to a wallet is lost when the wallet is revoked."

Right: The adapter accepts an attestation made to a wallet linked to the identity, whether the link is active or revoked. The attestation is a fact about the investor. The revoked wallet is refused as a recipient by every asset, and the identity keeps its credential.

Integration notes

• An Attester needs no ONCHAINID and no key on the Investor's identity. It attests on EAS as it already does. What makes its attestations count is the adapter's configuration, and each Issuer's decision to trust the adapter.

• EASClaimIssuer.getAttestationData(signature) is a raw read. It returns the data of an attestation even when the attestation is revoked, expired or from an attester the adapter does not accept. Decide on isClaimValid or getClaimStatus, never on the data alone.

• An identity holds one claim per issuer and topic. Bringing in a new attestation for the same topic through the same adapter replaces the record, and emits ClaimChanged.

• To renew, the Attester attests again and the Identity Owner repeats steps 2 and 3 with the new UID. A revoked attestation cannot be brought in again: the adapter reads the revocation.

• The Identity Owner removes the record with removeClaim(claimId) on its identity, with a CLAIM_SIGNER key: a CLAIM_ADDER key adds claims and cannot remove them. Removal is optional: a record whose attestation is revoked or expired no longer counts.

• The adapter reads attestations that exist on-chain, on its own chain. It does not read off-chain attestations or attestations made on another chain.

• Before relying on an adapter, an Issuer reads which schema it binds to each topic and which attesters it accepts, and follows SchemaForTopicSet and AttesterSet on the adapter. An attester added there widens what the asset accepts.

Related flows

• 05 Issue a claim to an investor : a claim signed by a Claim Issuer identity

• 19 Revoke a claim : revocation by a Claim Issuer identity. For an attestation, revocation happens on EAS

• 04 Add a trusted Claim Issuer : how an Issuer trusts the adapter for a topic

• 20 Remove a trusted Claim Issuer : how an Issuer stops trusting it

• External attestations : the adapter model and its trust assumptions