Abstract
Steganography is the art of secret communication. The goal is to hide a secret message in an unsuspicious object in such a way that no one can detect it. Nowadays, with the Internet spread and the emergence of digital supports (audio files, videos, or images), several philosophies of designing steganographic methods were proposed. One of the most usual embedding methods used with real digital images is the adaptive embedding algorithms, which is based on the modification of the cover image with a guarantee of a certain security level. These methods represent an important progress in steganography.In this Ph.D. Thesis, we present a fully automated procedure for the adaptive embedding of secret data in digital images. For this, after recalling the recent concepts of adaptive steganography, we first introduce a clear formalism to define a new "meta-method" steganographic approach based on "oracle", whichwe called ASO (Adaptive Steganography by Oracle). Then, we define a new steganographic paradigm called "the steganography by database paradigm", and propose a new selection criterion to further enhance the security of the transmission phase of ASO. Experimental results show that our embedding approach ASO provides the highest level of steganographic security. It is then currently the best or one of the best approaches of the state of the art.