Adobe Reader or Acrobat displays a "At least one signature has problems" message when signed PDF is opened. Signature validity is UNKNOWN. Signer’s identity is unknown.
VeryPDF PDF Security and Signature (Shell & COM & SDK) https://www.verypdf.com/app/pdf-security-and-signature/try-and-buy.html GENERAL QUESTIONS ABOUT DIGITAL SIGNATURES What is a Digital ID? When traveling internationally, a...