Knock, the iOS app that lets you unlock your Mac with Bluetooth instead of a password, is today being updated with Apple Watch support, bringing the same unlocking capabilities to Apple's upcoming wrist worn device.

Knock for iOS lets an iPhone pair to a Mac to bypass the need to enter a password, and Knock for Apple Watch will work in the same way. It will no longer be necessary to dig an iPhone out of a bag or a purse, because the Apple Watch with Knock Glance will also let users log into their Macs.

When we saw Apple Watch, we knew immediately that we had to make Knock one of the first apps available for it. Knock and Apple Watch are a match made in heaven. With Knock 2.0, leaving your iPhone in your bag or the other room isn't a problem. Whenever you open your Mac, Knock is right there at your wrist, ready to go. And with the Knock Glance, you can even unlock your Mac while you walk over to it -- or lock it as you walk away.

Today's Knock update also includes Touch to Unlock, which aims to introduce an extra layer of security for those who need it. With Touch to Unlock, unlocking a Mac with an iPhone also requires a finger to be placed on Touch ID, so it's no longer possible to unlock the Mac with just the iPhone in the event of a theft.

The new Touch to Unlock feature works in conjunction with the Apple Watch in a unique way that's similar to how Apple Pay works. When the Apple Watch is placed on the wrist, users are prompted to use Touch ID or a PIN code to unlock a Mac, and that enables the Apple Watch to continue to unlock the Mac as long as it remains in contact with skin on the wrist.

When removed from the wrist, the Apple Watch will no longer be able to unlock the Mac, effectively preventing it from being used to open a Mac with Knock installed without the owner's permission. Touch ID Apple Watch verification through skin contact lets Knock users take advantage of two-factor security without the hassle of needing to place a fingerprint on the iPhone each time a connected Mac is unlocked.

Knock for iPhone has received some criticism because it often takes longer to unlock a Mac with the iPhone than it does when entering a password, but some users have found it to be a fun alternative to the standard password entry for Macs. It's not clear if the Apple Watch will speed up the unlocking process, but Knock provides an interesting look at one of the ways the Apple Watch can be used by developers.