"Faster and safer than typing a password. Just Knock."

I tend to leave my phone on my desk. And that goes for both at home and at work. (I don't use 2-factor authentication, so I'm not terribly worried.) All that means is someone has to walk up to my desk, knock on my phone, and steal my passwords.

Hmm, I'm not thinking so. I think I'll stick with entering a password!

Just installed it. It works great. As somebody that always has their phone in their pocket, this is perfect and more than worth the $4.

How does the Mac authenticate a phone with Knock? Does it use HMAC-based One-Time Passwords (HOTPs) like Google Authenticator?

That looks terribly inconvenient. Especially the part with me deliberately knocking on my rather expensive smartphone.