PAdES: PDF Advanced Electronic Signature

PAdES digital signature

What is important to know about the PAdES standard?​

PDF files that are specifically adapted for electronic signatures through restrictions and extensions are called PDF Advanced Electronic Signatures (PAdES).

The term is also often used as PAdES standard or PAdES signature.

PAdES: ETSI specification​

The PAdES technical specification was published by ETSI (European Telecommunications Standards Institute). PDF is one of the most widely used formats for signed business documents. The concept of digital signatures was introduced in PDF 1.3 (1999) and continuously refined in later versions.

Digital signatures are especially relevant in company document workflows, including approvals, acceptance processes, and contract signing. They are also key for long-term archiving and document security.

Since PDF 1.3, the specification also defines how signatures are embedded, which PDF objects are involved, and which parts of a document are covered by the signature.

What exactly is PAdES?​

PAdES is the ETSI specification that defines how PDF files are adapted for electronic signatures. In this context, "Advanced" refers to extending the PDF standard for robust signature use cases.

Relevant ETSI documents:

For electronic signatures in general, standards such as EN 319 122 and EN 319 132 are used together with CAdES and XAdES. PAdES (EN 319 142) bridges these approaches into PDF-based workflows.

PAdES is also important when signatures must comply with European eIDAS regulations.

What are the advantages of PAdES?​

  • Long-term validity of electronically signed documents, even as cryptographic algorithms evolve.
  • Support for Long-Term Validation (LTV), so signatures can still be verified years later.
  • No special additional software required for basic viewing; standard PDF readers can open documents.
  • Signature validation data can be embedded in the same PDF file.
  • Suitable for workflows with multiple signatures and distribution across multiple parties.

Three types of electronic signature​

In practice, signatures are commonly distinguished as basic electronic signature, advanced electronic signature, and qualified electronic signature (QES).

  • Basic electronic signature: simple appended data used as a signature marker.
  • Advanced electronic signature: linked to a specific signer, using cryptographic controls to detect manipulation.
  • Qualified electronic signature (QES): highest legal assurance, based on qualified certificates and secure signature-creation devices.

A basic signature does not ensure tamper-proof integrity. Advanced signatures improve integrity and signer attribution. QES applies the strictest requirements and is legally equivalent to handwritten signatures in many legal contexts.

You can find more information about digital signatures here:

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