Restore Functionality on Unlocked Xperia Devices – Part Two

Restore Functionality on Unlocked Xperia Devices – Part Two

As you might have noticed, not too long ago, we featured an article that detailed how to get back lost functionality on unlocked Sony Xperia devices. To recap, a simple system modification allows you to gain back most of the features you lost when unlocking the bootloader of a recent Xperia device. The reason for the reduced functionality is that, when unlocking the bootloader, you lose the device’s internal DRM keys which are required for things like streaming protected media but also for advanced technologies like the BIONZ image processor or the Bravia Engine.

After further discussing the matter with the author of the mod, it turns out that the modified files deceive the DRM system and pretends to have working DRM keys readily available. Luckily some of the lost features only check for the availability of the DRM keys and don’t actually require them to be valid. You can think of it as a car (the specific features) and a car key (the DRM keys). In this case here, the car doesn’t need its specific key, it just needs any key for it to work. It doesn’t even need to match the car’s manufacturer, so to speak.


While this initially sounds like entirely good news, it also brings up a few important questions. Questions that only Sony can answer, but everyone should be aware of them.


If a (mostly) simple software modification can bring back features that, according to Sony, need valid DRM keys to work, then why can these features even work without the DRM keys?

At this point it certainly looks like you don’t need valid DRM keys to make certain features work that initially won’t work after unlocking. Various members have posted comparison images (for example here, or also in the OP) which show the BIONZ image processor and Bravia Engine working after flashing the modified files. While not everything seems to be working again right now, the author is constantly trying to improve the results. And after all, even the results we have today do show us that these features can be reactivated without valid DRM keys. They show us that all of the issues are artificial at best.


The left image has the BIONZ image processor disabled while it’s enabled on the right


If these features don’t need valid DRM keys to work, then why does Sony remove them anyway?

Obviously this point is guesswork only, but it sure looks like Sony is trying to hamper bootloader unlocking by artificially killing important features as a tradeoff for the unlocked device. On the other hand, maybe it’s more of an accidental screw-up on Sony’s part because, after all, they do tend to work closely with the development community.

In either case, the future will reveal which is the right answer, Sony has a chance to improve and to remove these restrictions, or they could potentially tighten up the security making it even harder to get back the lost functionality. Let’s wait for the Lollipop OTAs and discover what Sony has prepared for us.

Make sure to check out Part One and the thread for more info, and let us know your thoughts in the comments below.

About author


Freelance software developer and IT student, interested in technology and mobile developments ever since his first Siemens phone. In addition to technical deep dives for XDA-Developers, Fabian is also an enthusiast photographer and tries to combine his interests with unique and creative projects.

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