# Validate a timestamp certificate

If a signature displays the date and time, that time is the local time on the signer’s computer. However, a second date and time may appear in the Signature Properties dialog box, indicating that the signer uses a timestamp server. To validate a signature that contains a timestamp, you must obtain the certificate for the timestamp server and add it to your list of trusted identities. Otherwise, the timestamp appears in the Signatures panel as unverified, and you must validate the timestamp manually.

1. Click the Signatures button in the navigation pane, select the signature, and choose Validate Signature from the Options menu.
2. Click the Signature Properties button in the Signature Validation Status dialog box.
3. In the Signature Properties dialog box, click the Date/Time tab to view the timestamp authority, and then click the Show Certificate button. (This button appears in the Date/Time tab only if the signer used a timestamp server.)
4. In the Certificate Viewer, click the Trust tab to determine if the timestamp certificate is trusted. If it isn’t trusted, click Add To Trusted Identities. If a certificate for the timestamp server isn’t listed, request one from the signer.