Requires signal-cli: https://github.com/AsamK/signal-cli and Protocol::DBus to be used as module in FHEM (see in file documentation for more details)
See FHEM Forum (German) for more details https://forum.fhem.de/index.php/topic,118370.0.html
Added the compiled Raspberry libraries in the armv7l directory according to instructions on https://github.com/AsamK/signal-cli/wiki/Provide-native-lib-for-libsignal
For source and license of the lib libsignal_jni.so see https://github.com/signalapp/libsignal-client
For source and license of the lib libzkgroup.so see https://github.com/signalapp/zkgroup