id: attestation title: Where an agent was provisioned from is a claim somebody else signed status: open crates: [didbot-attest] dependsOn: [] exitCriterion: > An agent provisioned on a cloud instance carries an attestation whose evidence this project did not issue, and which a reader can check. #

attestation #

Attestation answers one question once, at provisioning: where did this come from, and is that source admitted. It is an audit artifact, not a credential.

The strongest claim available is about the node. Which session and which subagent are the harness's word, and nothing here pretends otherwise.

• A SPIFFE/SPIRE backend, as a portable wrapper over the others.

• A hardware root of trust, as a design stub.

• Say what each backend's evidence is worth to a reader who is not us. Done for the AWS instance identity backend; the SPIFFE/SPIRE and hardware backends still need their own paragraph once they exist.

• Spent nonces across a restart. SeenNonces is in memory, so a restart inside the window forgets what has been spent. Binding a claim to its request narrows what that is worth — a replayed claim can only re-run the provisioning it was signed for, which the account store refuses as a name already taken — but it does not close it for an account that has since been erased. Persisting them is durable state this crate has nowhere to put.

• An account that outlives its proof. A claim answers once, at provisioning, and is spent when it is admitted. An account that renews — a CI identity, a machine — proves itself again on every run, which is a second question this interface does not currently distinguish from the first. See account-types.

Done #

• What an admission established is recorded in the account's bot.did.registration record, as admittedBy and assurance.
• The backend interface.
• A node-credential backend, so a shared-secret holder cannot claim any allowlisted node.
• A seen-nonce store, so replay is prevented inside the window as well as bounded by it.
• An attestation claim is spent when it is admitted.
• A cloud instance identity backend, for AWS EC2. Verifies the detached PKCS#7/RSA-2048 signature over an instance identity document against this deployment's configured regional certificates — hand-rolled against der/spki rather than pulling the cms crate, which only exists as a pre-release and would have doubled the der stack already in the dependency graph. GCP and Azure are not implemented; the trait needed no change to make room for them.
• Execution environment recorded at provisioning. Provenance grew an optional environment field and an ExecutionEnvironment enum (laptop, container, cloud instance); the AWS backend is the first to set it, to CloudInstance. The node-credential backend leaves it unset rather than guess.
• Watch for clock skew. AttestError::Stale now carries the verifier's own clock alongside the claim's timestamp, and its message names clock skew explicitly rather than reading as a generic refusal. Applies to every backend, not just AWS's.
• Retired the agent.attestation lexicon — already done, in account-types: it folded into bot.did.registration. Verified rather than redone.
• The two missing properties of a detached-signature document — no audience, no expiry. Bounded by the seen-nonce store, exactly as account-types says: the tuple spent is instanceId + pendingTime, both read out of the signed document.
• A claim is bound to the request it was made for. The node-credential backend's signed string covers a digest of the request's identifying fields — agent id, handle, parent — beside the node, the nonce and the timestamp, under a v2 domain separator. A claim read off the path admits the provisioning it was made for and nothing else, and is refused for any other before its nonce is spent. A backend whose evidence is somebody else's document cannot do this: AttestationBackend::attest_for defaults to ignoring the request, and the AWS backend stays bounded by the seen-nonce store as account-types says.
• The binding is an issuer and a stable subject. The subject is accountId + instanceId, AWS's own identifiers, never a tag or a name. The claim's node_id is never trusted on its own — attest_at re-derives it from the verified document and refuses a mismatch.