The date and time for signatures is the local time on the signer’s computer. Some users, however, use a Time Stamp server, which is recorded in the Signature Properties dialog. To then validate a signature using a time stamp, you must add the certificate for the Time Stamp server to your Trusted Identities list. Otherwise, you will need to validate the time stamp manually.

To verify a time stamp certificate:

1. Right-click a signature and select Verify Signature.
2. In the Validation Status dialog box, click Properties.
3. In the Signature Properties dialog box, click the Date/Time tab to view the time stamp authority. Then click the Show Certificate button if the signer time-stamped from a third-party authority.
4. If the TSA certificate isn’t trusted, click Add To Trusted Identities. If the TSA’s certificate is not listed, you will have to request it from the signer.

Verifying a Time Stamp Certificate