Idea - Verifying citizens digital signatures via PrimeSign in the European Union

I know keybase.io is still in an early stage, so just an idea..

In many EU countries, citizens can apply for a digital signature on their citizen card or even on their mobile, referred as "mobile-signature". Besides for authorization purposes, it's also possible to digitally sign documents (such as PDFs), via PrimeSign. Businesses in many of the EU countries are even required to digitally sign electronic invoices via PrimeSign by law already. Currently the following countries within the EU have successfully deployed PrimeSign already:
- Austria
- Belgium
- Estonia
- Finnland
- Island
- Italy
- Principality of Liechtenstein
- Lativia
- Portugal
- Spain
- Sweden
- Switzerland

In theory, there could be a feature where an user uploads a signed document with his corresponding signature, such as a PDF, and keybase.io validates the signature against PrimeSign's validation API in order to map a relationship.

I'd suggest Austria as the first country for a test run, because PrimeSign is an Austrian company and the spread rate in Austria is quite good (currently around 650k of 8M citizens).

The issue names no repository files, tests, or entry points. Start by investigating PrimeSign's validation API and how signed-document uploads would fit into Keybase's existing identity flows; done would require a defined Austria-first verification scope and acceptance criteria.

Written by the indexing model from the issue text.