[Qgis-developer] Qgis custom buil to read obfuscated data

Barry Rowlingson b.rowlingson at lancaster.ac.uk
Fri Sep 16 05:33:32 EDT 2011


On Thu, Sep 15, 2011 at 11:14 AM, G. Allegri <giohappy at gmail.com> wrote:
> I've been asked to create a custom qgis, to be distributed via CD/DVD along
> with some data (vector and raster) that should be only visible and usable
> thorugh the customized qgis and not by any other tool.
> Has somebody in this list ever had to manage this kind of obfuscation?
> giovanni

 The keyphrase you are missing here is "DRM" - Digital Rights
Management - although I agree it essentially obfuscation. Its security
depends upon two things: the code having the cryptographic key to
decrypt the data, and the key not being accessible outside the code.

 The first part is easy - the second is impossible. I think every DRM
scheme has been cracked. The effort required varies. If you wrote a
Python plugin to do this, the user could look at your Python code and
see the decryption key (difficulty level: easy). If you wrote it in
C++, the user could disassemble the executable code and get the
encryption key (difficulty level: medium). If you put the code on a
circuit board, stuck it on a USB dongle, and made QGIS do calls to the
USB device to do the decryption, the user could take the USB device
apart, scrape off any epoxy covering your chips, stick digital logic
probes onto the chips, and get the keys out that way (difficulty
level: God-mode).

 The latter procedure, of digging into the hardware, has been done by
dedicated people working on cracking the DRM on games consoles,
primarily so they can run their own programs and operating systems on
them. You have to realise that an effective DRM scheme has to be
harder to crack than the gain obtained from cracking it. The guys who
crack games console DRM get the gains of massive respect from the
games community :)

 +1 for calling it obfuscation and not encryption though. The British
Library didn't get that right.

http://geospaced.blogspot.com/2010/02/great-british-library-drm-flip-flop.html

Barry


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