Digital signature timestamp

Digital timestamps mark a PDF signature with the time and date as proof of integrity. A timestamp shows that the contents of the document existed at a point in time, and are unchanged.


For added security, digital signatures can include a timestamp from an independent, trusted authority. Nitro Pro 7 is able to utilize a timestamp server to help ensure that the timestamp is precise and secure, since the system clock could be modified by a user.

To manage digital timestamp settings:

  1. In the File menu, select Preferences, expand Digital Signature, and select Time Stamp Servers

  2. If the list of Available servers is empty, or you want to add another timestamp server:

    1. Click New to add a new timestamp server. The Time Stamp Server dialog appears.

    2. Enter the name and URL of a timestamp server, and optional login information

    3. Click OK to save your settings

  3. To manage existing settings for a timestamp server, tick the Acquire timestamp from attestable server checkbox, select a timestamp server from the list of Available servers, and then do any of the following:

    • To update properties for the selected timestamp server, click Edit, and enter new information on the Time Stamp Server dialog

    • To remove the selected timestamp server, click Delete

    • To use a specified timestamp server by default for every timestamp, click Set Default. A star marks the default timestamp server.

  4. Click OK


TIP: If your default timestamp server is unavailable, Nitro Pro 7 uses the first available timestamp server on your list. You are advised to list them in order of preference.


When you look at the properties of a digital signature, time validity is shown as one of the following:

  • Signature date/time are from the clock on the signer’s computer

  • Signature is timestamped but the timestamp could not be verified

  • Signature is timestamped


For more information, see Digital signatures.

Digital signature timestamp