Despite increasing pressure abroad on Apple to open the iPod, iPhone and iTunes to third-party software and hardware providers, Apple Inc. remains focused on strengthening the digital rights management technology that protects its tightly coupled music hardware and software.

Two patent applications published on Thursday by the U.S. Patent and Trademark Office point to ongoing efforts by Apple to buttress its FairPlay DRM technology and its ability to control its products.

The first patent -- "Configuration of a computing device in a secure manner" -- describes a way to securely configure iPods using a digital signature file. The second -- "Secure software updates" -- details a method for securely updating digital rights management software.

The documents describe research that could extend Apple's control over the iPod and iPhone ecosystem in ways both positive and negative for consumers.

The configuration patent application looks like it will help avoid situations where a customer might purchase a song for an iPhone without sufficient room to store that song -- a quality of service improvement that would no doubt be appreciated.

However it could also allow Apple to arbitrarily restrict the number of songs that can be stored on a device even if the device has enough physical capacity to hold more songs.

"In the example, the portable media player computing device 102 is configured to have a particular initial song-holding capacity," the patent application says. "For example, the portable media player may be configured to hold twenty-five songs. ...A new configuration file may be provided with data indicating a capacity higher than the initial (or default) song-holding capacity."

The configuration patent application describes other possible usage restrictions, such as the ability to lock playlists. "Other features may be switched (typically on), such as enabling a feature such as access to music playlists on the portable media player computing device 102," the patent application explains. "For example, the 'key' may be 'playlist' and the 'value' may be 'off' or 'on.' In one example, where a default configuration is hard-coded, the presence of a configuration file effectively overrides the default configuration."

While it's doubtful that Apple is eager to unnecessarily restrict iPod and iPhone users, it may have reason to do so as a means to offer business partners such at AT&T, or perhaps Disney, the ability to sell tiered content plans.

One passage in the software update patent even hints that Apple may be contemplating giving its partners more of a role in the iTunes ecosystem. It describes a hypothetical scenario in which two vendors might want to dictate how the Apple's DRM performs. "For example, if the first vendor is a software provider and the second vendor is a hardware platform provider, the first vendor can provide the updated software module to the electronic device in a secure manner, but the second vendor can require that the software module be authenticated or validated before being installed on the electronic device," the patent application says. "Additionally, the second vendor might also provide their own level of encryption apart of any encryption provided by the first vendor."

That scenario, however, remains speculative. What is certain is that the company doesn't want anyone "tampering" with its portable device configuration files.

Programmers have already reported success cracking Apple's FairPlay DRM software, and Apple's secure software update patent application seems to address this. The pending patent describes how "improved techniques of the invention enable DRM software to be updated in a secure and controlled manner."

A significant aspect of the improved approach is that it can be automated so that user participation is not required. For example, if one version of Apple's DRM gets compromised, Apple can update its software without asking the user.

According to Apple's patent lawyers, user reluctance to agree to a software upgrade is the result of fear of viruses rather that, say, a preference of the functionality of the installed software over the update. "[C]onventional approaches for updating software on computers require substantial user participation," the patent application says. "The need for user assistance is problematic given that users are concerned about downloading and installing software on computers given the propensity of computer viruses that exist today."

This is a curious point to emphasize given that Apple's current Mac advertisements suggest viruses aren't much of a problem on its machines, but perhaps it's a nod to the number of Windows customers with iPods.

The software update patent application also describes automated updating as a convenience that eliminates the need to "burden users of electronic devices with software updates."