> 1) This will turn your phone SIM into a "master password" - equivalent to using the same password for all your accounts. If a "bad guy" steals your SIM (physi

> 1) This will turn your phone SIM into a "master password" - equivalent to using the same password for all your accounts. If a "bad guy" steals your SIM (physically or by tricking the phone company into reassigning the SIM), he will be able to log into every single account you have. Gaining access to the phone would give one master access. But this is usually the case anyways because you can reset all passwords via mail. Stealing the SIM won't give you access to the mail though. > 2) It will be a slow PITA when using a computer. While it would less of a PITA on a phone because you can copy-paste the code, phones are awkward and sub-optimal for many uses and many web pages. [...] I agree about the delay of email. That's bad. Typing a few digits is not really a problem.. you are typing your password also aren't you?