This is a very basic CLI tool to "uncompress" e-Szigno .es3 files and extract the encapsulated documents from it.
See https://e-szigno.hu for details.
NOTE: This tool does NOT validate digital signatures and should not be considered secure or feature-complete in any way. It is just a quick solution if you don't have Windows, or you cannot install the e-Szigno software.
List files in a .es3 document:
./eszigno.py ls INPUT.ES3
Extract files in an .es3 document:
./eszigno.py extract INPUT.ES3 [-o TARGET_DIRECTORY]