Verify

Check a Witnessed file

Drop in the original file and its timestamp token. We’ll recalculate the fingerprint and check the timestamp authority’s signature, so you don’t have to take anyone’s word for it, including ours.

Everything happens in your browser. Your files are never uploaded, and the certificate details in this page’s link are never sent to our server.

Evidence file The original photo, video, audio or document Timestamp token The .tsr file from the evidence pack

What this checks

The fingerprint. A SHA-256 hash of the exact bytes of the file. Change one pixel, trim a second of video or re-save the photo, and the fingerprint changes completely.
The timestamp. When the file was sealed, its fingerprint was sent to an independent timestamp authority, which signed it together with the time under RFC 3161. The token shows this exact file existed no later than that moment.
The signature. The authority’s signature is checked against the certificate it embedded in the token, which shows the token hasn’t been altered.

Check it yourself with OpenSSL

For a full check that includes the chain of trust up to the authority’s root certificate, use the files in the evidence pack:

shasum -a 256 evidence.jpg
openssl ts -reply -in XXXX-XXXX-XXXX.tsr -text
openssl ts -verify -in XXXX-XXXX-XXXX.tsr -data evidence.jpg \
  -CAfile tsa-root.pem

The Message data in the second command’s output must equal the file’s SHA-256. The third command should print Verification: OK. Download the root certificate for the authority named in the token from its own website (DigiCert, Sectigo or FreeTSA).