Glossary
Trust list: the difference between valid and trusted
A trust list is the set of root and intermediate certificates that a C2PA validator accepts as legitimate signers, so that a manifest whose signature is mathematically valid is reported as trusted only if its signing certificate chains to an entry on the list.
Illustration · PNG file
- Signature + IHDR
- iTXt XML:com.adobe.xmprecord
- tEXt parameters
- tEXt prompt / workflow
- tEXt invokeai_metadata
- eXIf
- caBX C2PA manifest
- IDAT pixels
- IEND
AI source type declared
The file labels itself as AI-made.
IPTC DigitalSourceType such as trainedAlgorithmicMedia is read from XMP and shown with its exact value.
Check an image →Why two checks exist
Anyone can create a certificate and sign a manifest; the signature will verify against that certificate. Trust answers the different question of whether the certificate belongs to a known signer. The C2PA ecosystem maintains trust lists of conforming signers, and validators may add their own. A manifest signed by Adobe, OpenAI or Google chains to a known root; a manifest signed by a self-made certificate does not, even though its bytes are intact.
How isGenAI reports trust
The C2PA checker and AI image detector print cryptographic validation and trust validation as separate facts and derive the evidence strength from both: trusted and valid with an AI action is strong; valid but untrusted is moderate; camera credentials count as capture evidence only when trusted. The report shows the trust state and validation codes so a reviewer can see which list decided the outcome.
Keeping the list current
Trust lists change as signers join and certificates rotate. A manifest reported as untrusted today may be trusted after a list update, which is another reason the report records the validator’s state rather than a bare yes or no.
Trust also has a time dimension. A trusted timestamp in the manifest records when the signature was made, so a certificate that expired later can still validate a signature created while it was in force.
How to use this term when checking a file
- Upload the original file to the AI image detector or the tool named on the page.
- Find the finding that uses this term under “How we checked” and read the source field it names.
- Weigh it by kind: a signed record, a declared field, a saved prompt and a matching copy are different strengths of evidence.
- Remember that absence of a record is not evidence of a human author.
Frequently asked questions
Can a C2PA signature be valid but untrusted?
Yes. Validity checks the maths; trust checks whether the certificate chains to an accepted list. isGenAI reports both.
Who maintains the C2PA trust list?
The C2PA conformance programme publishes lists of conforming signers; validators may apply additional lists.
Is an untrusted manifest worthless?
No. It still proves the content is unchanged since signing by that certificate; it does not prove who the signer is. isGenAI rates it moderate.
Why does the same file show different trust in different tools?
They use different trust lists or versions. The validation codes in isGenAI’s report explain its result.
Sources
Definitions follow the published standards linked above; the isGenAI behaviour described is the deployed checker as of October 2026.