# What is C2PA metadata?

Source: https://passreal.com/guides/c2pa

C2PA, shown to users as Content Credentials, is an open standard for attaching a signed provenance record to a file. The record states who made the image and with what tool, and it is bound to the content by a hash, so edits are detectable. It can be removed, and it never proves that an image is true.

## The short version

C2PA stands for the Coalition for Content Provenance and Authenticity, the group
that publishes the specification. Its goal is to let a file carry a record of
its origin that software can check. When that record is displayed to people, the
feature is called Content Credentials. The record itself is called a C2PA
Manifest.

## What a manifest contains

The explainer describes a manifest as containing one or more assertions.
Assertions are statements, such as which tool produced the image, which actions
were applied to it, or that it was made by a generative model. They are gathered
into a claim, and the claim is digitally signed by whoever creates the manifest.

A manifest is stored in a JUMBF structure, a general-purpose box format.
ExifTool reads that structure and lists it as C2PA for JPEG, PNG, TIFF-based
files and other formats. In a JPEG it travels in application segments, which is
one reason ordinary image libraries do not show it: they read the segments they
know and ignore the rest.

## Why it is called tamper-evident

The manifest includes a hash that represents the content at the time it was
created. The explainer calls this the hard binding. If someone changes the
pixels after signing, the hash no longer matches, and a validator can say so.
In the explainer's words, this means the provenance data can be said to be
tamper-evident.

That wording is exact and worth reading slowly. The manifest does not stop edits
and does not stop removal. It makes an edit visible to anyone who checks, if the
manifest is still attached.

## Why it can still be removed

Because the record travels inside the file, anyone can take it out. The
explainer says so directly: asked whether provenance metadata can be removed,
it answers yes. Ordinary processing does it by accident. The IPTC organisation
points out that uploading to social media is one of the main ways metadata gets
stripped, intentionally or not.

The specification's answer is the soft binding. A soft binding links a piece of
content to its manifest through an invisible watermark or a fingerprint lookup,
so a manifest kept in cloud storage can be found even when the file lost its
copy. The explainer pairs the hard binding with a soft binding for what it calls
durable credentials. Whether a given image has one depends on the tool that made
it.

## What it proves and what it does not

A valid manifest tells you who signed a claim and that the content has not
changed since. That is useful for newsrooms and for tools that record edits.

It does not tell you that the picture is true. The explainer is explicit that
the information alone cannot tell you whether the digital content is true,
accurate or factual, and that Content Credentials do not provide value
judgments. A signed manifest on a staged image is a correct record of a staged
image.

The reverse also holds. A file without a manifest is not proof of anything. Most
photographs in circulation never had one.

## C2PA and the labels on social networks

Meta announced in February 2024 that it would label AI-generated images on
Facebook, Instagram and Threads using two open standards, C2PA and IPTC. It
later changed the wording of the label from Made with AI to AI info, after
photographers complained about images labelled for light AI-assisted edits. If
your photo carries an AI marker because an editing tool wrote one, the cause is
a metadata field, which you can inspect. The guide on
[why Instagram labels photos as AI](/guides/instagram-ai-label) covers the
fields in detail.

## What it means for PassReal

PassReal removes C2PA manifests, IPTC fields, XMP blocks and text chunks by
re-encoding the image from a pixel array, then shows a report of how many
markers were found and how many remain. On a Gemini export, 174 went to 0. That
is a statement about declared provenance only. It is not a claim about
detectors and not a claim about SynthID, which is a separate pixel watermark.
The how-to for doing it by hand is
[how to remove C2PA from an image](/how-to/remove-c2pa).

## Questions

### Is C2PA the same as Content Credentials?

Yes in practice. The specification calls the record a C2PA Manifest, and Content Credentials is the name used for the feature that shows it to people.

### Does C2PA prove an image is real?

No. The C2PA explainer says provenance information alone cannot tell you whether content is true, accurate or factual. It tells you who signed the claim and whether the content changed after.

### Can a C2PA manifest be removed?

Yes. The explainer answers yes when asked, and tools such as ExifTool can delete the JUMBF block from several formats. Soft bindings are the approach for finding a removed manifest again.

### Is C2PA the same as SynthID?

No. C2PA is metadata that sits beside the pixels. SynthID is a watermark written into the pixels of media made with Google tools. A file can have either, both or neither.

### Which platforms read C2PA?

Meta said in 2024 that it reads C2PA and IPTC signals to label AI images on Facebook, Instagram and Threads. Support elsewhere varies, so check each platform's own documentation.

Try it: https://passreal.com/app (three images free)