C2PA

The manifest is the core data structure of the C2PA standard. It acts as a cryptographically signed container that holds a set of assertions about a content asset. These assertions can include who created the asset, when and where it was created, what edits were made, and by which software or actor. The manifest is designed to be hard bound to the asset, meaning it can be embedded directly into the file's bitstream (e.g., in a JPEG or PNG) or provided as a separate, linked resource. This binding ensures the provenance data cannot be easily stripped or lost during distribution.

The concrete implementation of the C2PA specification, functioning as a digital 'nutrition label' for media. A Content Credential is a cryptographically signed set of assertions that travels with the asset.

• Tamper-evident: Any modification to the asset or credential breaks the signature
• Hard Binding: Metadata can be embedded directly into the file's bitstream (e.g., JPEG, PNG)
• Soft Binding: Credential stored externally and referenced via a secure hash
• Assertions: Include creator identity, capture device, edit actions, and AI generation flags

Adobe Photoshop, Lightroom, and Microsoft Designer natively support Content Credentials, with verification available at https://verify.contentauthenticity.org.

The core data structure within the C2PA architecture that contains a set of assertions about a content asset and a cryptographic signature binding those assertions to the asset.

• Assertion Store: Contains claims like c2pa.actions (edit history), stds.schema-org.ClaimReview, and thumbnail hashes
• Signature: Generated using the signer's private key, verifiable with a public certificate chain
• Ingredient References: Links to parent manifests, forming an attribution chain
• Claim Generator: Identifies the software or device that produced the manifest

A manifest is created at each significant lifecycle event—initial capture, editing, or publication—creating a verifiable provenance chain.

A method of provenance attachment where the manifest is cryptographically embedded directly into the asset's bitstream, making the metadata inseparable from the content.

• JPEG: Manifest stored in a JUMBF box within the file structure
• PNG: Embedded in an iTXt chunk
• AVIF/HEIF: Stored in a dedicated metadata box
• Video: Per-frame or GOP-level embedding in MP4/ISOBMFF containers

Hard binding ensures the credential survives common file operations like copying or transcoding to compatible formats. If the binding is stripped, the signature validation fails, signaling tampering.

A sequential, verifiable record of all actors and processes that contributed to a digital asset's creation or modification. Each link is a signed manifest referencing its predecessor.

• Initial Capture: The camera or recording device creates the root manifest with sensor data and timestamp
• Edit Operations: Each editing application appends a new manifest describing actions (crop, filter, AI inpainting)
• Publication: The final platform adds distribution metadata

Verifiers traverse this chain backward to reconstruct the complete provenance trail. A broken chain—where a parent manifest is missing or its signature invalid—immediately flags the content as untrusted.

A cryptographic process proving that specific data existed at a particular point in time, critical for establishing temporal provenance in C2PA manifests.

• TSA Integration: Manifests can include a timestamp token from a trusted timestamp authority (RFC 3161)
• Anchoring: Timestamp hashes can be anchored to distributed ledgers for long-term, decentralized verification
• Anti-Backdating: Prevents an attacker from creating a forged manifest and claiming it was signed before a compromise event

Combined with certificate revocation checks (OCSP stapling), trusted timestamping enables verifiers to determine if a signature was valid at the time of signing, even if the certificate later expires or is revoked.

A complementary W3C standard for tamper-evident, cryptographically signed digital credentials. C2PA leverages Verifiable Credentials for identity assertions within manifests.

• Issuer: The organization or device that signs the credential (e.g., a camera manufacturer)
• Holder: The entity presenting the credential (often the content creator)
• Verifier: The party checking the credential's validity (the content consumer)
• Selective Disclosure: Enables revealing only specific claims (e.g., 'photographer is a verified journalist') without exposing full identity

C2PA manifests can embed Verifiable Credentials as assertions, linking content to real-world organizational or individual identities with cryptographic certainty.