The C2PA Standard, Explained
C2PA defines an open technical format for signed content provenance. This reference maps the main parts of the specification and explains how verification, trust, and conformance fit together.
What is C2PA?
C2PA is a technical standard published by the Coalition for Content Provenance and Authenticity. It defines how a producer can attach a signed manifest to media so that a consumer can inspect the declared origin, recorded actions, and assertions without relying on a central registry. Official C2PA specifications.
How the specification is structured
The specification separates the provenance data model from storage in particular media formats and from validation rules. That separation lets JPEG, PNG, WebP, AVIF, MP4, and other formats carry comparable provenance while format-specific boxes or chunks hold the manifest store.
Manifest and manifest store
A manifest contains signed claims and assertions. A manifest store can contain multiple manifests and identifies the active manifest for the current asset. Ingredients can preserve manifests from source files used to create the asset.
Claims
A claim is the core signed statement about an asset. It identifies the claim generator, format, and instance, and references assertions that carry more detailed facts.
Assertions
Assertions are structured data records inside a claim. Common examples include actions, ingredient references, thumbnails, and declared digital source types. An assertion describes what a producer stated; it is not independently observed truth.
Ingredients
An ingredient is a referenced source asset used to produce the current asset. A composited image, for example, may reference a background photo and a logo. The amount and quality of ingredient information depends on what the producing tool recorded.
Signatures and hash binding
A cryptographic signature covers the claim and its assertions, while hashed data binds the manifest to the asset bytes. If the signed record or the bound bytes change, verification can fail.
Verification
Verification checks structural validity, hashes, signatures, certificate status, timestamps, and trust anchors. A successful result means the credential is intact and correctly bound; it does not prove every statement in the manifest is factually true.
Trust lists and trust anchors
C2PA uses certificates and configurable trust anchors. A manifest signed by an unfamiliar or untrusted certificate can be structurally valid while its signer is not trusted by your chosen policy. Verification tools should keep integrity and trust decisions visible rather than collapsing them into one score. C2PA trust list repository.
Conformance
The C2PA project maintains conformance testing for implementations. Conformance helps ensure tools interpret the specification consistently; it does not certify that every signed claim is truthful. C2PA conformance testing repository.
Versions and compatibility
C2PA continues to evolve. Manifests carry version information, and readers should handle both current and legacy forms. A missing or older manifest is evidence about the file format version, not a verdict about authenticity.
C2PA and Content Credentials
C2PA is the underlying technical standard. Content Credentials are the user-facing expression of provenance built with that standard. They are complements, not competing specifications.
Inspect a real C2PA file
Reading the specification is clearer with a signed file in front of you.
Core C2PA guides
For plain-language context, start with the core concepts and then read how verification fits together.