In this paper we tried to give an all-round view of steganography, both used to exchange messages and watermarking.
First we gave an outline of the problem, telling also some of the history of this quickly developing field.
Then we showed the different techniques invented, from the simplest to the more complex ones, trying to evaluate them under many points of view. Major emphasis was put on data hiding in images, for the techniques involved are usually more mature than the corresponding ones for other kinds of informations. Image encoding algorithms can also be representative for manipulation of other types of media.
Then we gave an outline of the problems involved with watermarking, a field that has come into light after the development of broad band worldwide digital networks.
In the end, we showed some of the attacks that can be attempted against steganography and watermarking, and their degree of success.
Steganography and digital watermarking are undergoing a development process similar to that of encryption, where there was a continuous invention of new techniques for encryption followed by successful breakings and new improvements of them. [PAK98]
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Matteo Fortini