A manifest store (JUMBF boxes in the file or a sidecar) holds manifests with assertions (actions such as created, edited or AI-generated, ingredients, thumbnails, hard bindings by content hash), a claim listing the assertion hashes and a claim signature: COSE_Sign1 with an X.509 certificate, usually with an RFC 3161 timestamp. Edits produce new manifests that reference previous ones as ingredients. The specification was at version 2.4 in 2026 and is on the ISO fast track.
Validation checks the signature, the certificate against a trust list (the C2PA trust list for conforming products since 2025), the hash bindings and the ingredient chain. Credentials can be stripped, so their absence proves nothing, and a valid manifest proves only what the signer asserted; researchers have also found ways to alter content within excluded byte ranges. The C2PA inspector reads manifests locally.