Digital PDF Certificates
Trust and Authenticity
Signing a PDF file with a digital signature requires a bit of background
knowledge. When the PDF reader tries to decide if a signature is valid then
it looks at the certificate used to sign the document. A signature can
make sure that nobody tampered with the content of the document since it
In addition, the signature is used to determine if you trust the content.
Trust is based on the certificate behind the signature. Certificate trust
depends on the issuer of the certificate. The reader will trust a
certificate if you have told it to trust the issuer of that
By default the Adobe Reader only trust certificates issued by Adobe or
one of their partners. This means that it will show a certificate
warning if the certificate wasn’t issues by one of these authorities.
Microsoft Windows also uses certificates for validating software vendors
and content providers. You can configure your Adobe Reader to trust these
issuers in addition to the Adobe partners. This extends the range of
certificates that will show as valid certificates when you receive or
create a signed document.
You can also get a certificate that doesn’t stem from one of the
trusted providers. Then it is up to you to have your document
recipients add that certificate to their list of trusted
certificates. If they do that, then your signed documents will
show as validated and trusted if they are received in their