It would be great to be able to authorize a login for another machine. I could request a login on any machine and have an email/sms sent to my smartphone and cl

It would be great to be able to authorize a login for another machine. I could request a login on any machine and have an email/sms sent to my smartphone and click the link there (alternatively, scan a QR code), and get authorized on the machine initiating the login. Email/SMS would be an obvious security hole for people who just click "OK" without reading, though. I guess a QR code would be secure anyway.