08 Jun
What is pades and why should I use it?
PAdES (PDF Advanced Electronic Signature) is an electronic signature format dedicated to signing files with PDF extension.
It is also the most convenient and popular method for signing documents and applying a signature in the PAdES format is a simple procedure – you just need to use software from your e-signature provider.
The use of the above-mentioned format is a significant facilitation in the receipt of signed documents, among others:
- Integrity preserved by the creation of a single file containing the content as well as the signature itself.
- Preventing modifications to a document after a signature has been added.
- Possibility of including a graphic representation indicating the correct signature of the file.
PAdES Standardisation – ETSI TS 103 172
PDF documents can be stored for long periods of time. This means it is necessary to have tools to ensure the authenticity of the document itself for an equally long period of time. Especially needed when the certificate with the signature has expired/the certificate authority has been liquidated/the cryptographic algorithms used to create the certificate are no longer trustworthy.
The ETSI TS 103 172 technical specification defines so-called signature levels and was introduced to define how PDF files in PAdES format should be verified and archived.
- B level – the most basic profile containing an electronic signature valid at the date of submission.
- T level – similar to B level, but adds a timestamp to ensure that the signature exists on a specific date and time.
- LT level – an extension of T level. Adds Verification Related Information (VRI) data to the Document Security Store (DSS). Allows verification of the validity of a signed document after a long period of time when the signing environment (CA) is no longer available. Recommended for advanced signatures. Regulated by national regulations, which must be checked each time.
- LTA level – adds a timestamp to the LT level and VRI data for the Time Stamp Authority (TSA). Allows the authenticity of the signature to be confirmed despite any events limiting its validity. Recommended for qualified signatures, compliant with eIDAS regulations and requirements resulting from upcoming legislation.
PAdES, as an electronic signature format, can produce legal effects and be used in legal proceedings or tenders. Issued in an EU member state, it is accepted in all other member states. The EU recognises three distinct digital signature formats: PAdES, XAdES and CAdES-all compliant with the eIDAS regulation.
