Apple has secured a patent on technology that makes it feasible for the company to offer portable user accounts in future.

A user account contains all a user's documents, data and other information.

The notion of portable user accounts has been debated for years. Rumours have often suggested the company has planned to make user accounts portable in this way - potentially using an iPod.

What this suggests is that, if the technology is applied in this way, Mac users will be able to store their Home folder on an iPod, which they can then connect to any Mac, making all their usual applications and data available to use securely on that Mac.

Now the rumours take a step closer to reality, with the US Patent Office granting Apple US Patent 7,120,785, which describes a "method and apparatus" for portable user accounts.

The patent describes technologies that let user accounts be stored on an external storage device and moved to another computer.

The computer operating system would be built to recognise user accounts held not just on the computer itself, but on such external storage devices.

"By coupling the external, portable data store to another multi-user computer, a user is able to log-in to any supporting multi-user computer and be presented with their user configuration and user directory," the patent filing explains.

"Since the data store that stores the user account is not only external but also portable, a user can simply tote the data store to the location of different multi-user computers. In one embodiment, the external, portable data store can not only store the user account but can also provide general data storage. In another embodiment, the external, portable data store can be a portion of a portable computing device (for example, a media player) that provides other functionality besides data storage," it adds.