The dependency list is missing "Smart phone".<p>Anyone who's spent time in hotels in recent years knows that since switching from mechanical keys to magnetic keys, sometimes the keys break and the guest is locked out of their hotel room, which of course they never discover until trying to open the door. Then they have to go to the front desk, probably stand in line, and request a replacement key.<p>Using smart phones as authentication devices suffers from this exact same problem. I can't speak for iOS but every android phone I've had has experienced slow operation, crashes, and other kinds of issues at inopportune moments. When I am trying to log into something to perform a 5 minute task I don't want to be delayed for 15 minutes while my phone chugs away at whatever.<p>I'm just one geek, but I have spent a lot of time thinking about "alternatives to passwords". I have concluded the password is king. We use passwords everywhere, and we will continue to use passwords everywhere, until someone invents something better. In 100s of years nobody has done that yet (Mechanical keys are a kind of password).<p>Instead of trying to replace passwords which are reliable and simple to use, with complicated authentication systems which are not reliable and not simple, we should focus our efforts on improving password authentication in our existing apps (no more limitations), building great password tools like keepass.info, and encouraging the average user to use password tools and practice good password habits.