When you use Adobe Acrobat or Reader to open PDF documents that were signed or certified using certificates, you see the following message:

"A new security settings update is available from Adobe.  Would you like to install it now?"  This dialog is a trusted Adobe dialog referring to updates to the root certificate list (AATL) in Acrobat or Reader.


AATL or Adobe Approved Trust List is a program that allows millions of users around the world to create digital signatures. The signatures are trusted whenever the signed document is opened in Adobe Acrobat 9 or Reader 9 or later.  The list of trusted certificates is updated from time to time in case some certificates have been added, renewed, or have expired.

These updates are distinguished from the standard product updates for Acrobat or Reader, which can be triggered by choosing Help > Check For Updates.

If you want to check for certificate updates, choose Edit > Preferences > Trust Manager > Click Update Now under the section Automatic Updates. The same update dialog box opens. Using this option, the certificate updates are loaded from a trusted server.

To enable the automatic update check, choose Edit > Preferences > Trust Manager > Load Trusted Root Certificates From An Adobe Server.  To enable the automatic check without any notification, deselect Ask Before Installing.  

Preferences menu

Assuming that you have enabled the automatic check, the certificate updates are triggered under the following conditions:

  1. you open a file that has a digital signature, and
  2. you have never checked for updates before, or
  3. you have checked before, but
    1. 28 days have elapsed and
    2. there is a new update available

You can select Yes and the trusted certificate list in Acrobat or Reader is updated. If you want to see the trusted list, choose Open Adobe Reader > Document > Manage Trusted Identities. In the window that opens, choose Display > Certificates. The entire Trusted Certificates list currently installed with your Reader appears.

Enterprise deployment

If you are working in an enterprise environment and want to control these settings for an enterprise deployment, use the Customization wizard to activate or deactivate these options.

Customization wizard

Additional information