Can your mobile phone become a replacement for manually typing in a password? That’s the promise of a new application called Knock, which launched on Tuesday, which uses an iPhone paired with a Mac desktop or laptop computer to log you in to your locked machine. The system takes advantage of the newer low-energy Bluetooth technology to enable the connection between the two devices, allowing you to just knock (you know, knock, like on a door) on your iPhone to login. But the company has ambitions to expand beyond unlocking computers, and envisions bringing Knock to browsers to log into websites, and eventually letting you “knock” to open anything, including even your home’s front door, perhaps. The company was founded by William Henderson, who previously worked on the Wallet team at Square, and Jon Schlossberg, who led user experience at Bonobos.