An e-Certificate is providing services for issuing certificates and business licenses or doing any act from a government agency by using the electronic signature or the digital signature that applies to the certificates or the licenses.
We have already the e-Certificate service for using or you can use via our API service (the API document).
You can create the PDF/A3 file, and include both the XML file and the digital signature by this command,
curl -X POST “https://api.esigns.cloud/documents/pdfa-xml/digitalsign” -H “Content-Type: multipart/form-data” -H “API-Key:<your api key>” -F “file=@<pdf file path>” -F “file=@<xml file path>”
For using how to create the PDF/A3 (include both the XML and the digital signature).