iButton contact keys

Flipper Zero has a built-in 1-Wire pad to read iButton (DS1990A) keys, also known as TouchMemory or Dallas keys. This technology is quite old but still widely used around the world. It's based on 1-Wire protocol and doesn't have any authentication, so Flipper can easily read these keys, save IDs into the memory, write IDs to blank keys, and emulate the key itself.