GPO’s Seal of Authenticity
From the Government Printing Office:
For almost 150 years, the U.S. Government Printing Office (GPO) has been the official disseminator of Government documents and assure users of their authenticity.In the 21st century, the increasing use of electronic documents poses special challenges in verifying authenticity, because digital technology makes such documents easy to alter or copy, leading to multiple non-identical versions that can be used in unauthorized or illegitimate ways.
GPO uses a digital certificate to apply digital signatures to PDF documents. In order for users to validate the certificate that was used by GPO to apply a digital signature to document, a chain of certificates or a certification path between the certificate and an established point of trust must be established, and every certificate within that path must be checked.