Signing Originals

Builder assembles a manifest declaratively — title, intent, assertions, ingredients — and realizes it in a single sign() call that embeds the signed manifest into the image bytes and returns the result. Nothing touches disk; no timestamp authority or other network service is contacted.

Create intent

A brand-new original uses Builder::create():

use Automattic\VIP\C2PA\Builder;
use Automattic\VIP\C2PA\Signer;

$builder = Builder::create(
    'photo.jpg',
    'http://cv.iptc.org/newscodes/digitalsourcetype/digitalCapture'
);
$signed = $builder->sign($unsignedBytes, 'image/jpeg', $signer);

The second argument is an IPTC DigitalSourceType URL declaring where the content came from — digitalCapture for a camera photo, trainedAlgorithmicMedia for generative-AI output, and so on. An unknown or empty value falls back to digitalCapture.

(For derivatives of an existing asset, use Builder::edit() instead — that’s its own chapter.)

Assertions

Assertions are the manifest’s claims about what happened. addAssertion() takes the assertion label and its data as a JSON string:

$builder->addAssertion('c2pa.actions', json_encode([
    'actions' => [['action' => 'c2pa.created']],
]));

The extension validates that the JSON parses but otherwise passes assertions through verbatim — any label/shape the C2PA spec (or your pipeline) defines is fair game.

The claim generator

The manifest records what software produced it. By default that reads wp-c2pa (with the extension’s version); override it to attribute the credential to your organization or product:

$builder->withGenerator('NASA');

An empty or whitespace-only name resets to the default.

Signing

$signed = $builder->sign($bytes, 'image/jpeg', $signer);

sign() may be called with any Signer. The returned string is the complete signed image — write it wherever the original came from. The builder itself is not consumed; its accumulated state is applied fresh on each call.

Failures throw C2paException with a c2pa signing failed: … message (malformed assertion/ingredient JSON fails earlier, at the add* call, as invalid input: …).