Apple may use power adapters to help prevent the theft of portable devices, a patent granted today shows. The company has developed a concept which would selectively disable the power adapter for an iPhone, iPod, MacBook, or similar hardware when it becomes clear that the device is no longer being used with permission, forcing the battery to run dry or limiting device functions themselves until certain conditions are met. Triggers could be as simple as a timer but could also include more complex situations such as wandering outside of a set geographical area, according to Apple. The power supply could also be set only to work with a general device class or even the system that originally came with the adapter, Apple says.

The technology could be implemented through either separate guardian hardware or a component integral to the power adapter itself and might use a device's Internet connection or GPS positioning to verify its state.

To prevent users from unintentionally locking themselves out of using their own components, however, the patent would allow for users to enter a passcode that either derestricts the power supply entirely or reauthorizes it for use with given equipment. In some cases the key could be content already loaded on to a portable media player, such as a song.

Originally filed in late 2005, the patent has yet to be implemented in any shipping Apple products but would cover personal computers and virtually every class of handheld, including cellphones, GPS mapping units, music players, and PDAs.