AU-10 Non-repudiation

Control statement

Provide irrefutable evidence that an individual (or process acting on behalf of an individual) has performed [Assignment: actions].

Guidance

Types of individual actions covered by non-repudiation include creating information, sending and receiving messages, and approving information. Non-repudiation protects against claims by authors of not having authored certain documents, senders of not having transmitted messages, receivers of not having received messages, and signatories of not having signed documents. Non-repudiation services can be used to determine if information originated from an individual or if an individual took specific actions (e.g., sending an email, signing a contract, approving a procurement request, or receiving specific information). Organizations obtain non-repudiation services by employing various techniques or mechanisms, including digital signatures and digital message receipts.

Implementation

Signed agent task records

Non-repudiation: the task record binds outputs (sha256 subjects) to the agent identity and approvals under an ECDSA P-256 signature; tampering with output or predicate fails verification (tested 2026-10-24 by the agents session). Partial: one example, signed with an operator-held file key (not per agent), no Rekor and no trusted timestamp, so timestamps are only as trustworthy as the signer.

Status: partial.

Evidence:

All controls. Source: OSCAL component definition reti-platform and NIST SP 800-53 Rev 5 (public domain).