As irritating as it could be for an organization to lock you into its ecosystem by encrypting their protocols, it’s important to admit that it presents an attractive problem. Cracking encryption could be extra hassle than it’s value, although, particularly when a tool offers you all of the instruments you could do an end-run round their encryption.
We’ll clarify. For [Valdez], the encrypted communication protocols between a DSC alarm panel and the management pads on the system have been severe impediments to integration into Home Assistant. Whereas there are integrations accessible for these alarm panels, they depend on third-party clouds, which signifies that not solely is your safety system probably telling one other laptop all of your juicy particulars, however there’s additionally the very actual chance that the cloud system can both break or be shut down; keep in mind the Chamberlain MyQ fiasco?
With these info in thoughts, [Valdez] got here up with a intelligent workaround to DSC encryption by specializing in bodily interfacing with the keypad. The machine has a typical 16×2 LCD and a 25-key keypad, and somewhat poking round with a multimeter and a $20 logic analyzer ultimately confirmed that the LCD had an HD44780 controller, and revealed all of the traces wanted to decode the show with an ESP32. Subsequent up was interfacing with the keypad, which additionally concerned somewhat multimeter work to find out that the keys have been connected in a 5×5 matrix. Ten GPIOs on the ESP32 made it potential to nearly push any key; nevertheless, the ten relays [Valdez] initially used to do the switching proved unwieldy. That led to an optocoupler design, sadly not as clicky however actually extra compact and streamlined, and enabling full management over the alarm system from Home Assistant.
We love this answer as a result of, as [Valdez] aptly factors out, the weakest level in any system is the place the place it will probably’t be encrypted. Info has to stream between the person and the management panel, and by offering the digital equivalents to eyes and fingers, the underlying encryption is moot. Hats off to [Valdez] for a wonderful hack, and for sharing the wealth with the HA neighborhood.