Each VAT or pro-forma invoice available in the My Account link on the DIPOL website is in the form of PDF file that can be opened by popular PDF readers, e.g. Adobe Reader (http://get.adobe.com/reader/). These programs also allow for the verification of the document for any changes of its content, which could take place after signing it with qualified electronic signature.
If you install on your computer the certificate issued by the Certum Certification Authority to DIPOL company, used to sign electronic documents, Adobe Reader will allow you to verify the authenticity of the documents with the signature.
Otherwise, the opened PDF document will inform you that:
"The validity of the document certification is UNKNOWN. The author could not be verified."
So, it means that the certificate has not been installed on your computer and/or has not been approved by you as trusted.
To verify the authenticity of our documents, you should install the certificate and approve it as trusted.
The procedure description:
  • Click on the "Signature Panel" tab located in the upper right corner of the Adobe Reader window.
  • It displays information about the signature, including the date and time of signing and alterations to the document since it was certified.
  • To add the certificate to the trusted identities, click on "Certificate Details..." from the expanded "Signature Details" branch.
  • It will show the following information ("Summary"):
  • Click on the "Trust" menu and then on the "Add to Trusted Certificates..." tab.
  • Adobe Reader will display the following message:
  • You should confirm the request by clicking "OK". In the new window you will be able to approve the certificate.
  • Leave the default options selected: "Use this certificate as a trusted root" and "Certified documents". After acceptance of the certificate by clicking "OK", close all windows and the PDF document.
  • When you open the document again, the previous message "The validity of the document certification is UNKNOWN. The author could not be verified." will be replaced with "Certified by DIPOL Sp. J. , DIPOL Sp. J., certificate issued by Certum Level IV CA."
From now on, all VAT and pro-forma invoices issued in electronic form by DIPOL with the company's qualified signature will contain such information.