Using PAdES

PAdES, or PDF Advanced Electronic Signatures, is a set of standards designed to enhance the security and longevity of digital signatures in PDF documents. It is particularly useful for ensuring the integrity and authenticity of documents over long periods, making it ideal for legal and official documents that require long-term validity. PAdES is compliant with European eIDAS regulations, which means it is legally binding across the EU, providing a robust framework for electronic signatures that can be recognised as having the same legal effect as handwritten signatures in many cases.

One of the key benefits of using PAdES is its ability to ensure the long-term validity of signatures. Even after the initial signing certificates expire, PAdES signatures can remain valid through the use of timestamping and validation data, ensuring that documents remain legally admissible even years after they were signed. This feature is particularly important for documents that may need to be referenced or used in legal proceedings long after their creation. Additionally, PAdES signatures can be easily verified using widely available PDF software, eliminating the need for specialised tools. This ease of use, combined with its legal compliance and security features, makes PAdES a preferred choice for securing digital documents in both business and government contexts.

In the Document Advanced API, we automatically use PAdES for the signatures we apply inside the PDF document. Despite this, Web Trust allows you to opt in the PAdES signature, for the rest of the Document workflows. It’s enough to specify the property

...
pades: true
...

Restrictions

When using PAdES, there are some rules that need to be respected:

  1. The signatureFieldsType inside of each document must be set to signature.

  2. The number of documents to be signed must be less than or equal to 5.

Failing to comply with the previous constraints will result in a 400 error while trying to create the signature.

If a document was already signed using PAdES, then markPages will be ignored.

Consider that PAdES is used automatically in the Document Advance API, so those restrictions also apply here.