C2PA (Coalition for Content Provenance and Authenticity)

C2PA is an open standard for cryptographic provenance metadata on digital content — primarily images, video, and audio. It is backed by Microsoft, Adobe, Google, OpenAI, Sony, and the BBC.

A C2PA-tagged image carries invisible, signed metadata that discloses who produced it, when, with which tool — and whether it was AI-generated or manipulated. The information is machine-readable (browsers and marketplaces can read it) but not visible to the human viewer in normal display.

In the context of the EU AI Act, C2PA is the most likely standard for fulfilling Article 50(2): providers of AI image generators must mark their output "in a machine-readable format", and C2PA is exactly that.