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Certificate for signing a pdf file
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Posted by admin  · 16-10-2020 - 15:48

Hello,

Adobe, and other programs, displays the validity of the certification is uknown message when the certificate/CA is not trusted by Adobe, so you need to accept (trust) it or use a certificate accepted in Adobe as trusted.

We recommend you to check if AATL is updated in your Adobe PDF reader (https://support.globalsign.com/aatl-document/how-manually-update-adobe-approved-trust-list-aatl-adobe-acrobat-reader) and the certificate/CA you are using is trusted by Adobe. 

On https://stackoverflow.com/questions/13979845/signed-pdf-showing-message-the-validity-of-the-document-is-unknown-itext you can read more information when Adobe displays that message.

Regards.