A Citizen Card Environment, a MOA-SS instance, a PKCS12 file or a Java KeyStore can be used as a signature creation unit. Here, both Citizen Card Environments for chip cards and also the mobile phone signature are supported as Citizen Card Environments. That way, official signatures (by means of MOA-SS) can be created by government agencies on the one hand as well qualified signatures by citizens. The layout used for the signature visualisation that is to be provided can be configured individually by the government agency or the citizen, but its default configuration is orientated around the convention for the official signature layout.
As of version 4.0, PDF-AS supports the creation of signatures according to the Advanced Electronic Signature (PAdES). A reconstruction of the signature as well as verification of the signature on the basis of a printout is not possible here (except for official signatures).
The following diagram shows the architecture of PDF-AS and its individual program components. The architecture is designed modularly to the extent that other software components can be easily built on the PDF-AS core.
The following three components form the heart of PDF-AS:
- PDF-AS Library
- PDF-AS Web
- PDF-AS Client
The PDF-AS library maps all the necessary functions for the processing of PDF documents as well as for initiating the signature creation process inside a JAVA library. This library essentially forms the basis for the development of any other applications. In addition, the two libraries “sigs-pades” and “sigs-pkcs7detached” belong to this library. These two libraries must be present in the class path at the runtime of PDF-AS.
PDF-AS Web, for example, is built on the PDF-AS library and provides a Web interface to PDF-AS. This Web interface supports a simple user interface (Web interface), but can also be used by external applications to embed PDF signatures (interface to external applications).
PDF-AS also uses the PDF-AS library and provides a simple command line program with which PDF-AS can be automated or run using a command line (PDF-AS Client and Command Line Interface).
Comprehensive application documentation or alternatively documentation on the Web interface can be found here.
The modular architecture of PDF-AS lends itself to developing simple applications based on PDF-AS. Within the scope of the Austrian eGovernment, two important core components based on PDF-AS have already been developed, i.e. PDF-OVER for the creation of signatures and a verification service for the verification of signatures.
Source code is available under: https://apps.egiz.gv.at/releases/pdf-as/