IMHO, for most people the best interface would be a physical key (with software keys on it). That is something like a smartcard or ubikey, and even a way of obt

IMHO, for most people the best interface would be a physical key (with software keys on it). That is something like a smartcard or ubikey, and even a way of obtaining multiple copies, like with physical keys. My employer rolled out a smartcard based PKI about 15 years ago, where you may own more than one card (optionally in sim card size for usb tokens) so, for example, you can have one in the office and have another one in your home office. Works quite well (modulo mobile) for now abour 30K employees. And, combined with RFID on the cards, you can call elevators, open doors, pay for food, etc. Now if hardware manufacturers had standardized on appropriate hardware (chassis, keyboards, smart devices…) some 20 years ago, instead of trying (and failing) all kinds of software "solutions" … and thinner and thinner hardware, so no such cards or sticks would fit anymore …