I really like the idea but I wonder if the additional effort required will limit adoption. It's much easier for me to tap my fingers on a keyboard than it is to get out my phone, unlock it, open an app, and focus it on the computer screen. Yeah I know I sound really lazy, but I think this makes a difference in general adoption.

This reminds me of using NFC for payment. Swiping a credit card is still a lot easier than getting out my phone, opening an app, holding it up to merchant's NFC scanner, and clicking to confirm.

Both are awesome ideas because they have other benefits (not having to remember a password for this, not having to carry around a credit card for NFC), but the UX needs to be tweaked so that the effort is <= current methods.