I ran across this app quite a while ago, but just finally got around to installing it and have found it to be extremely useful. MacID is an iOS and Apple Watch app that lets you use Touch ID from iOS as a way to authenticate and login to a Mac. So instead of having to type your password into the Mac via a keyboard you can just tap your iOS screen or your Apple Watch and you are in!
How I am Using the App:
There are two reasons why this app is so useful to me. The first reason is due to my Mac setup. I am running a Mac Mini that is hooked up to a 27" MonoPrice HD monitor and for whatever reason this monitor is harder to wake up than my teenage daughter is first thing in the morning. It generally takes me a good half dozen taps on the keyboard and then another 10-15 seconds for the monitor to finally wake from sleep mode before I can start typing in my password. Now that I am using MacID, all I do is tap the MacID complication on my AppleWatch and then tap the icon of the login I want to authenticate and I'm logged in. So with 2 taps of my Apple Watch while I'm walking over to my Mac I have saved myself the 30 seconds of waiting I used to have each time I wanted to login.
The second and more time saving use I have for this app is the case where my daughter wants me to log her into my Mac so she can play MineCraft. This request generally happens when I have just sat down in another room. Now instead of having to get up, walk in the other room, sit down at the Mac and go through my 30 second login routine I just tap my Apple Watch a few times. Seriously, this is almost as good as having a Harry Potter wand or being able to use The Force. Almost...
Is This Secure?
MacID uses the Touch ID built into your iPad or iPhone as a way to authenticate (i.e. ensure that you are indeed you). So only people who can unlock your iOS device with Touch ID will be able to use this app to login to your Mac. Plus they need to be within Bluetooth range of your Mac. Bottom line...it is a safe and secure way to more conveniently login to your Mac. I don't know anything about how encrypted the communication between this app on your iOS device and your Mac is, but I'm guessing it doesn't need to be encrypted at all. There shouldn't be any password information flowing between the devices. The free app installed on your Mac stores the login password and the iOS app is simply sending an unlock command via Bluetooth, so even if someone were to intercept the communication they wouldn't get any information by doing so. So I think this app quite secure to use in the home environment as a quicker and easier way to login to your Mac.
There are a ton of other features this app has that I haven't really tried out yet. It has the ability to lock your Mac, which is nice for me because there are times I don't want my kids piggybacking into my Mac after I walk away so they jump on and do something. You can also receive notifications of when your Mac is being logged into and even setup the app such that when you (and your iOS device) get close enough or far enough away from your Mac the app automatically logs you in or out. My Mac is located right next to a main path in my home so I would be triggering this feature too often it if I activated it, but for some people this could be even handier than tapping your iOS device or Apple Watch to login. The app also has the ability to control iTunes audio on your Mac and move things you have copied to the clipboard on your iOS device clipboard to your Mac. Like I said, I just started to scratch the surface with MacID. It is well worth a few bucks to buy this app and try it out for yourself. This one app alone has added a huge amount of utility to my Apple Watch.