Japan's IC cards are weird and wonderful

Summary

While I was in Japan over winter, one thing that stood out to me was the incredible public transport system. Efficient and reliable, as expected, but the tap-in-tap-out gates at the stations were suspiciously fast. The London Underground gates don't work nearly as quick with Google Pay or any of my other contactless cards - what gives? I spent some time researching what makes Japan's transit card system (IC cards) so unique compared to the West, and all of the interesting bits I learned along the way. Basics of NFC Near-field communication is a set of protocols which lets two devices communicate with each other without physically touching, using radio waves at 13.56 MHz (defined by ISO/IEC 14443). It's used all over the place: When you use a contactless debit card, Apple Pay, or Google Pay, you are using EMV, standing for Europay, Mastercard, Visa (archive), operating over ISO/IEC 14443. When you tap into a station on the London Underground using an Oyster card, your card uses MIFARE DESFire to communicate with the gate reader (but if you are using a payment card, it uses EMV instead). Note that the Underground originally used MIFARE Classic, but "the security...is terrible" (archive) , resulting in the cards being trivial to clone, defeating its security. Access control systems (archive) for buildings, doors, etc. tend to use MIFARE Classic. Places like your office building, your gym, etc. Wait... didn't you just say that the security of MIFARE Classic is terrible? Someone could clone my keycard - or worse yet, get into my (whatever) without even needing a keycard? Yes, and it's worse than you think. That's why it's considered legacy, and fortunately nothing security-critical really uses MIFARE Classic anymore. I mean, you're not worried about someone breaking into your hotel room, right? What's interesting about Japan (and Asia in general) is that they have their own type of NFC which basically does not exist in the West: FeliCa, a standard developed by Sony, offi...