Technical points about adaptive steganography by oracle (ASO)

ASO [1] is an adaptive embedding scheme that has proved its efficiency compared to HUGO [2] algorithm. It is based on the use of a detectability map that is correlated to the security of the embedding process. The detectability map is calculated using the Kodovský´s ensemble classifiers[3] as an oracle, which preserves the distribution of the cover image and of the sender´s database. In this article, we give the technical points about ASO. We give the details of the detectability map computation, then we study the security of the communication phase of ASO through the paradigm of the steganography by database. Since the introduced paradigm allows the sender to choose the most secure stego image(s) during the transmission of his message, we propose some security metrics that can help him to distinguish between secure and insecure images. We thus significantly increase the security of ASO.