Validating Signatures and Seals

To validate the signers’ signatures in validation tools such as the EU DSS Validator you have to do a few more steps compared to when you validate the document seal. Occasionally we are asked:

• Why do the EU DSS Validator and Adobe Reader only show a Qualified Electronic Seal?
• The document was signed with itsme® Qualified Electronic Signature, but I only see a Seal. Why?

This article answers these questions and explains how to validate both the Seal and the signers’ signatures.

Seal or signature

Penneo’s Qualified Electronic Seal is applied to all signed PDF documents, irrespective of signing methods. This proves the integrity of the document, including the presence of the correct signatures. The evidence of the signers’ signature, including the signers’ personal signing certificates, is attached to the sealed PDF.

These attached files can be extracted and validated separately.

How to extract and validate the signature in EU DSS Validator

To validate the signature simply follow these steps. We use Adobe Reader as an example, because it is a widely used PDF viewer and available for free.

How to download the file for validation:

1. Open the PDF document in a PDF reader
2. Click the paperclip icon in the side menu, to open the Attachments menu.
3. Right click on the XML file named Signature for... and save the file on your computer.
4. Do the same for the file titled Signed data for… (This file is only present for AdES signatures)

NOTE: The number of XML files depends on the signature type. Penneo Advanced Electronic Signatures signatures contain 2 files per signer (Example above), whereas documents signed with Qualified Electronic Signatures only contain 1 file per signer. Currently, QES is only available with itsme®. See screenshots below.

AdES:

QES:

How to validate the Seal in the EU Validator:

1. Go to EU DSS Validator
2. Under Signed file select the signed PDF file
3. Click Submit

How to validate the AdES signature in the EU Validator:

1. Go to EU DSS Validator
2. Under Signed file add XML file from Signature for...
3. And under Original file add the file from Signed data for...
4. Click submit

How to validate the QES signature in the EU Validator

1. Go to EU DSS Validator
2. Under Signed file add the XML file from Signature for…
3. Click Submit

For further information, please see Penneo's articles Electronic Signature & Electronic Seal Standards and Verifying the validity of digital signatures.