Decoding an air conditioner control's checksum with differential cryptanalysis

Thanks for reading! If you decide to do a project with IR communication, be sure to research things like signal interrupts and hardware support for generating waveforms. On the Pi I'm basically using a busy loop to decode the signal in Python. It's not too elegant or efficient but it can usually get you what you need.

A more accurate (and more efficient) approach would be to either use a microcontroller that can record timestamps during pin interrupts from the IR receiver, or use a chip that has hardware support for receiving signals. The ESP32 has a nice peripheral for sending and receiving IR signals without tying up the main processor(s):

https://esp-idf.readthedocs.io/en/v1.0/api/rmt.html

But if you just need to decode and send a few different signals and only have a Pi, my approach works well. Been using it for close 1.5 years now without any trouble.

I don't have any hard science for you, but I have noticed that iPhones do a significantly better job at filtering infrared compared to the Android phones I own (mostly older Nexus devices). I typically use an Android to see if LEDs are emitting instead of my iPhone because it's so much fainter on the iPhone.

The photo in my article was taken with an Olympus mirrorless camera.

Disclosure: not an expert. IR/UV bleeding depends mostly on 3 things: sensor sensitivity, materials of and coatings on lenses, raw sensor data processing. Professional cameras are usually equipped with IR blocking filters and UV filter is "standard practice". Results can vary drastically from seeing under clothes [1] to barely registering IR lighting.

[1]: http://abcnews.go.com/GMA/story?id=126782&page=1