The ETSI standard supports a European Commission Action Plan that seeks to build on existing experience in this area and further improve the efficiency of cross-border use of electronic signatures. Open technical standards, such as those produced by ETSI, provide an ideal means for ensuring the required interoperability such that, for example, a document created and signed in one Member State can be validated in another.
The standard also 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 new standard was developed by ETSI's Electronic Signatures and Infrastructure (ESI) Technical Committee in collaboration with PDF experts. PDF is defined in a standard (ISO 32000-1) published by the International Organization for Standardization (ISO), so the ETSI activity included reviewing and documenting how ISO 32000-1 can satisfy the European Directive. The resulting PAdES standard, ETSI Technical Specification (TS) 102 778, also 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.
PAdES is complementary to two other Electronic Signature concepts also developed by ETSI's ESI committee, both widely recognised within the European Union and suited for applications that do not involve human-readable documents: Cryptographic Message Syntax Advanced Electronic Signatures (CAdES) and XML Advanced Electronic Signatures (XAdES).
As with all ETSI standards, the PAdES, CAdES and XAdES standards can be downloaded free of charge from the ETSI website at http://pda.etsi.org/
PDF and PAdES – major enablers for electronic commerce
PDF provides an electronic analogue to paper documents and also allows richer digital content to be stored and presented to the user. The transition from paper to PDF is eased by PDF’s ability to electronically represent nearly any form of paper document and by its support for electronic signatures which are today's equivalent of yesterday's ink signatures.
An electronic signature is a paperless way to sign a document using a unique credential associated with a given person that is logically attached to or associated with the document, carrying an authority equivalent to a handwritten signature. It can be used to authenticate the signer as well as to detect any changes in the document made after it was signed. Electronic signatures are recognized as a catalyst to electronic commerce, notably Internet transactions. Availability of electronic signature techniques has already been a major stimulus to eBusiness and eGovernment.
For PDF documents, the signature data is incorporated directly within the signed PDF document, much as an ink signature becomes an integral part of a paper document, allowing the complete self-contained PDF file to be copied, stored and distributed as a simple electronic file. The signature can also have a visual representation as a form field, just as it might on a paper document. A significant advantage of PAdES is that it is being deployed by means of widely available PDF software: it does not require development or customization of specialized software.
