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C2PA for Ad Tech

How ad platforms use C2PA checks to read who signed a page and what they declared about AI, as one input to their own buying rules.

Start signing freeCheck a file free
A signed page's record is looked up by the Prebid module in a signed dataset at the edge, with no call to Encypher during the auction. Each ad slot then carries imp.ext.c2pa with four fields, v, id, ref and att, and buyers check the signature and decide; if the record is missing, the auction goes on.
Each ad slot carries a small signed object, 1 KiB or less. Buyers check it and set their own policy.
Manifest checksC2PA manifest: The signed label itself: a small package inside a file that records who signed it, what they declared and how to check it.
Signed publisher pages can be checked for who signed them and whether they changed before they are sold as inventory. Checking is free.
Digital source typeDigital source type: A field in the label that says how content was made: captured by a camera, made by AI, or a mix.
The label carries the publisher's own declaration of human-made or AI-generated content, a field software can read.
Trust List anchoringC2PA Trust List: The list of signing authorities that conforming C2PA checkers trust by default.
Checks chain to the official C2PA Trust List, so the signal is standard and works across vendors.

How it works

  1. Create a free account.

    No card needed.

  2. Sign your next file or page.

    Your name and the time go into a C2PAC2PA: The Coalition for Content Provenance and Authenticity: the group that publishes the open standard for content labels. label inside it.

  3. Anyone can check it, free.

    The check shows who signed it, what they declared, and if it changed.

    Open the checker

Why ad tech needs a label

A signed text mark gives a yes or no anyone can check, valid or changed; a statistical pattern runs through a model and gives a probability, such as 72 percent likely AI.
A cryptographic mark gives a checkable answer. A statistical pattern gives a probability.

Sites filled with AI-made content take a growing share of ad spend. Filters that guess at AI text fall behind each new model. Buyers want a signed record of who published the page. The buyer still sets the rules.

Tested against the standard

A checker trusts a signature when the signer's certificate was issued by a certificate authority on the C2PA Trust List, and trusts the timestamp when it comes from an authority on the C2PA TSA Trust List. The Conforming Products List shows the signing tool was tested.
Trust is about who signed and when. It does not make the content true.

Encypher's product is on the official C2PA Conforming Products ListConforming Products List: The C2PA's public record of products that passed its conformance program., dated May 26, 2026. Our signing and timestamp services are on the official C2PA Trust Lists. That matters when a signal has to stand up for both buyers and sellers.

Keep reading

Create. Mark. Endure.

Where content came from becomes a signed fact on the placement, not a guess.

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