I have developed an APP in Apache Cordova (HTML5 and Javascript), which is in production and already has thousands of users, and now requires users, Portuguese citizens, to digitally sign a document. The Public Administration in Portugal has a Digital Mobile Key that allows the authentication of the citizens through an SMS for the mobile phone, also allowing the digital signature.
Is anyone aware of any API or code needed to make this signature? I'm researching a lot, but the documentation is very meager.