Next, we download and decompile the applet using JD-GUI. Known form other IoT devices (cc: @internetofshit) the applet authenticates the user locally, there is no backend involved (so we can skip auth completely) 🤦 The applet connects to the heat pump using a TCP socket.
Next, we waste 4h to remind ourselves that Java uses big-endianness 😅 and that you are sending the correct value but in the wrong order, you idiot! 😬 Meanwhile we have some fun with the hardcoded secrets 😂, and we waste hours to figure out which value represents which sensor.
Finally, we integrate everything into #HomeAssistant using a command_line sensor that updates every 60 seconds. Now my friend can enjoy all important heat pump sensor readings on his phone and can finally uninstall Java 🥳
