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HTC Android T-Mobile G1 (photo by Edlimagno - CC-BY)

Google sure caused a lot of confusion here! Their very vocal announcements of the Android project on 5 November 2007 raised the expectation that Android phones would contain open software and be readily hackable, but the only Android phone released to date has been locked down. What gives?

One cause for concern was that the most up-to-date version of the Android software development kit (SDK) was only released to selected developers. Everyone else received only an older version.

Similarly, Android itself was initially only available to device manufacturers.

Both of these issues appear to have been resolved on 21 October 2008, when the entire source code was released under the Apache License, so that anyone may change the source code and compile their changes.

The Apache license allows the code to be used freely, but does not force users of the code to release their own code under the same generous terms. This makes it possible (and legal) for a company to keep secret the code they have written to integrate Android with their hardware.

T-Mobile has done just that with their G1 smartphone, made by HTC. Although the G1 incorporates Android software, which has been released by Google as open source, the version that comes with the G1 phone is not supplied with source code. Further, the G1 device is designed so that it can only run an operating system that has been signed cryptographically with a key that is known to T-Mobile but has not been released publicly. The end result is that T-mobile can enforce which software will run on the device.

No doubt in time there will be more Android devices released by various manufacturers – and some of those manufacturers are likely to have a more enlightened view as to what software may be installed into their devices

In the meantime, Google has made available a “Developers” version of the G1 that can run unsigned code and is not locked to any network operator. This device is only available to those who sign up as Android developers, which involves payment of $25 and the acceptance of an agreement but is not otherwise limited.

Just to complicate things even further, the G1 ships with some additional applications written by Google and installed “on top of” Android. These applications are not open source and are not permitted to be disassembled or modified.

So there you have it – the Android mobile operating system is itself open source, but if you get it as a cryptographically-signed binary on a restricted device then that version does not come with source code and that device won’t accept a modified version of Android.