Inspect Content Credentials
Whether a file carries a signed record of how it was made, who signed it, and whether the bytes still match. "Valid signature" and "recognised signer" are shown as separate answers, because they are separate questions.
Provenance tool
What this checks
Content Credentials are a signed record of how a file was made, embedded in the file itself. This reads that record and checks it against the file’s actual bytes.
The validator is about 8 MB of WebAssembly, so it is only downloaded once a file is found to actually contain a manifest. It runs on your device, and the certificate lists it checks against are served from this site rather than fetched from anyone.