PDF Advanced Electronic Signatures (PADES)
While PDF and ISO 32000-1 provide a framework for digitally signing their documents, PAdES specifies precise profiles making it compliant with the European eIDAS regulation (Regulation on electronic identification and trust services for electronic transactions in the internal market). The eIDAS regulation enhances and repeals the Electronic Signatures Directive 1999/93/EC.[3][4] EIDAS is legally binding in all EU member states since July 2014. An electronic signature that has been created in compliance with eIDAS has the same legal value as a handwritten signature.
An electronic signature, technically implemented based on PAdES has the status of an advanced electronic signature. This means that;
it is uniquely linked to the signatory;
it is capable of identifying the signatory;
only the signatory has control of the data used for the signature creation;
it can be identified if data attached to the signature has been changed after signing.
One important benefit from PAdES is that electronically signed documents can remain valid for long periods, even if underlying cryptographic algorithms are broken.
PAdES recognizes that digitally-signed documents may be used or archived for many years – even many decades. At any time in the future, in spite of technological and other advances, it must be possible to validate the document to confirm that the signature was valid at the time it was signed – a concept known as Long-Term Validation (LTV).
The PAdES standard, ETSI Technical Specification (TS) 102 778, introduces a number of adaptations and extensions to PDF to satisfy the Directive’s requirements. ETSI will feed these European-specific elements back into ISO for inclusion in the next release of the PDF standard, ISO 32000-2.
TruePact support PADES. It provides a service for signing PDF documents with e-signature.
Based on : https://en.wikipedia.org/wiki/PAdES