Use Your iPhone as a Proximity Key to Lock/Unlock Your Mac
Kentucky-based The M.H.A.
released their Mac-based security program Airlock on Tuesday. Airlock unlocks your Mac when you approach it, based on the proximity of the Bluetooth transceiver on your iPhone (or later-gen iPod touch). The Mac will lock when your device leaves the preset range, but Airlock also accepts your account password as backup, in case the device is unavailable or its battery dies: since you'll be leaving Bluetooth turned on all the time, the battery will drain even faster than normal.
The program runs as a System Preferences pane, which features a "radar screen" that displays the distance to your device. The display actually works pretty good as a locator if you've forgotten where you put your iPhone: a dot will show up on "radar" in the correct distance relative to your Mac. A slider lets you set the distance that Airlock will use to activate or deactivate, so if you want to set your screen to lock as soon as you leave the room, just set the device outside the door and adjust the slider until the dot shows outside the glowing ring.
In addition to locking the screen, Airlock can be configured to do other actions when it determines your device is in or out of range. For example, when you come in-range, Airlock can automatically launch a particular application or Automator script, allowing you to log in to chat or change your status. Similarly, actions can be configured for out-of-range, like logging the date and time in an email.
The developer is working on a bug-fix update to deal with known issues where newer-model iPhones are not detected by the iPhone-selection sheet within the Airlock preference pane, and where some iPhones can't be detected at all, with no dot appearing on the radar screen, and with the range indicator remaining black. There is also an issue which they believe is caused by a bug in Mac OS X's Bluetooth implementation, causing connection loss to Bluetooth devices, that ithey are appealing to Apple to resolve.
Airlock supports Intel Macs running Mac OS X 10.5 or higher. It costs $7.77 for a single license
, which works on up to three computers. Multi-site licenses are also available.