You can use the AxCrypt app in offline mode. AxCrypt will work without internet(offline) also. So no need internet to decrypt the encrypted files. For more information, please visit here https://www.axcrypt.net/blog/axcrypt-online-vs-offline/
If user login in the AxCrypt app-default AxCrytp app in online mode.
If the user chooses to work Online Mode, Now you are able to see the status on the AxCrypt application title bar Like–“AxCrypt Premium”.
If the user chooses to work offline Mode, Now you are able to see the status on the AxCrypt application title bar Like –“AxCrypt Premium Offline”.