Uninformed: Informative Information for the Uninformed

Vol 10» 2008.Oct

Can you find me now? Unlocking the Verizon Wireless xv6800 (HTC Titan) GPS
In August 2008 Verizon Wireless released a firmware upgrade for their xv6800 (rebranded HTC Titan) line of Windows Mobile smartphones that provided a number of new features previously unavailable on the device on the initial release firmware. In particular, support for accessing the device's built-in Qualcomm gpsOne assisted GPS chipset was introduced with this update. However, Verizon Wireless elected to attempt to lock down the GPS hardware on xv6800 such that only applications authorized by Verizon Wireless would be able to access the device's built-in GPS hardware and perform location-based functions (such as GPS-assisted navigation). The mechanism used to lock down the GPS hardware is entirely client-side based, however, and as such suffers from fundamental limitations in terms of how effective the lockdown can be in the face of an almost fully user-programmable Windows Mobile-based device. This article outlines the basic philosophy used to prevent unauthorized applications from accessing the GPS hardware and provides a discussion of several of the flaws inherent in the chosen design of the protection mechanism. In addition, several pitfalls relating to debugging and reverse engineering programs on Windows Mobile are also discussed. Finally, several suggested design alterations that would have mitigated some of the flaws in the current GPS lock down system from the perspective of safeguarding the privacy of user location data are also presented.
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