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FactLock it. You get proof of that exact file, at the time of the public transaction that recorded it.
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Share the file and its proof.
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Check the proof free online at Open Proof. For larger files, use the Free Mac Proof Utility. A free Windows utility for larger files is not available yet.
The Free Mac Proof Utility is the Free FactLockFile Viewer for Mac.
A match means the checked file still matches its FactLock record. It does not tell you whether a claim or photo is true.
The check runs on your device. The file is not uploaded. Only the proof’s record ID is looked up online.
The instant you capture, FactLockCam hashes the exact media bytes. One changed byte produces a different fingerprint. A canonical capture manifest — fingerprint, length, MIME type, UTC metadata, device key class — is hashed and signed by your owner key, a software key held in the phone's secure storage. The file and the signature are checked as separate results.
Read next
- Mechanism Tamper-evident photo and video verification Five stages from capture to recipient check, including what the signed record contains. Read
- Concept Tamper-evident verification The reference record: exact-file fingerprint, signed manifest. Read
- Explainer How to show a photo was not altered Why an earlier record beats a later argument, and what a recipient actually sees. Read
- Category Provenance vs AI detection A comparison against a signed record is a different job from guessing whether pixels look synthetic. Read
- Ceiling Threat model What a passing check can show, what it does not, and what is disclosed in every manifest. Read
- Live Can you tell which one changed? Pick the altered copy, then run the shipping verifier on both files. Read
