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I have found a very interesting paper here related to this topic.
I just want to have views/ideas from other professional about how we can protect GIS data using Cryptography or Digital Watermarking?
Any suggestions, especially for Administrative layers of a country where source of layers is same for every company so output is also same more or less.
I am interested in some methods like one suggested here
Fake features - fake roads or trap street - http://en.wikipedia.org/wiki/Trap_street can be easily spotted - fines up-to £20 million have been applied for reproduction without license to from digital data.
Open Street Map is highly aware of this 'A Copyright Easter Egg' in terms of mapping, is a feature that is drawn in a distinctive way in order to help identify its original author. It may be a nonexistent, or slightly or heavily distorted, map feature, or its name may be wrongly or unusually spelt.
At a slightly lower level, you may want to have a look at this presentation about securing GIS data, a variation of which was given at FOSS4G in Denver earlier this year.
Before going to very advanced scheme to prevent data theft, you should first make sure that the data is only available to the authorized users and prevent others to gain unauthorized access. Many of the commonly used solutions are reasonably weak in this area. A framework like Geomajas has a client-server architecture which allows you secure your GIS data in a few ways. Some of the advantages include:
Data can be filtered on the server (fine grained, including filtering features or even attributes of features). This assures unauthorized data cannot be discovered at the client.
It prevents leaking credentials to the data sources by acting as a security proxy. By putting the Geomajas server in the demilitarized zone, you can completely shield your data sources from the internet (like WMS/WFS servers).
It allows single sign-on with other services.
The security can be integrated in the application (adding custom policies).
Admittedly, such schemes do not prevent authorized users to copy data and distribute to unauthorized users. Schemes like watermarking can help in such cases to be able to find the source of the data leak.
As @Mapperz said road data can include easter eggs to prove copyright violation. (I am aware of a case where this was used to show violation but I cannot find it now after searching.) However, this does not help with polyline data.
You can approach this using digital watermarking. There are a large number of papers on this. I have two examples which you can find on IEEE or ACM.
Michael Voigt and Christoph Busch, "Feature-based watermarking of 2D vector data", Proc. SPIE 5020, 359 (2003); doi:10.1117/12.476815
Michael Voigt, "Watermarking geographic vector-data using a variable strip-size scheme", Proc. SPIE 6505, 65051V (2007); doi:10.1117/12.704557
I would recommend Google searches for "polyline digital watermarking", "GIS digital watermarking" and other variations. Secondly, if you follow citations to the Voigt papers you will find more. A large number of them are written by Chinese or Japanese researchers so the English translation can be difficult and the heavy maths involved make it worse.
Being simplistic, the watermarking techniques involve moving some of the points in special ways such that there is a signal in the points which can be detected if you know how to look for it but the changes are less than the noise error. Some of the techniques are "blind" - this means that the watermark can be detected without the original data.
