Geographic data and steganography - Using Google Earth and KML files for high-capacity steganography

Steganography is the art of hiding the existence of information, whereas cryptography only aims at hiding the content of a message. Most steganographic algorithms try to embed data into images, audio or video files that provide reasonable capacities. However, such systems are often vulnerable to simple statistical attacks. In this paper, in order to provide an appropriate alternative to the currently used algorithms, we examine the information hiding properties of vector data that is used by many geographic information systems in great quantities. Unlike watermarking, we focus on maximising embedding capacities rather than on robustness, while still providing security against statistical attacks. Our implementation that uses the KML format known from Google Earth and other map services can replace more than 20% of the original data with hidden messages, provided that a lot of numerical geodata is present in the KML file. Thus, our algorithm can hide about twice as much as current algorithms for images. Yet, virtually no distortions are inflicted to the cover data.