Add support for PAdES.

While PDF and ISO 32000-1 provide a framework for digitally signing their documents, PAdES specifies precise profiles for use with advanced electronic signature in the meaning of European Union Directive 1999/93/EC. 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).

Vendor would like to know if there is a serious demand for this standard on the market. Vote for this feature if your company use/require it.