theoretic model for steganography

Throughout history, people have sought secret means of protecting their property and their knowledge from being stolen. Watermarking and copyright marking, for instance, attempt to keep property secure from thieves. Cryptography and steganography aim to keep knowledge safe from spies.
In the spatial domain, we first present an efficient multi-level embedding procedure for 3D polygonal meshes. Our algorithm, which is the first technique to take advantage of the full vertex features of these meshes, achieves high capacity relying on three independent degrees of freedom. We deal with distortion through a new modified multi-level embedding procedure. Embedding that relies on the angle between triangle planes is not appropriate to a long and narrow triangle, because such embedding can cause larger distortion for a larger radius. To solve this, we embed messages based on the arc length, which efficiently avoids apparent distortion while it achieves high capacity. Based on this approach, we also propose a virtual multi-level embedding procedure to support point-sampled geometries. It produces a unique virtual triangle for each point and embeds messages by modifying the point based on virtual geometrical properties. Then, we propose an adaptive minimum-distortion estimation procedure to achieve higher capacity in each vertex by changing the vertex’s position with minimum distortion distance.
As we demonstrate in this dissertation, the proposed approaches, based on both the spatial and representation domains, can be combined to achieve higher capacity. In other words, we successfully combine both domains for steganography. Experimental results show significant improvements in terms of capacity, visual appearance, and performance with respect to the most recent, advanced techniques. These improvements will make this kind of application more widely available.Finally, all of our approaches are blind schemes, requiring no 3D cover model for message extraction, and they are secure, since retrieving the message without the key is virtually impossible. These algorithms are simple yet efficient and are robust against affine transformations. Our techniques are a feasible alternative to steganographic approaches for 3D models
. Our technique is adaptive, simple, efficient, and secure, and has proven to be feasible in steganography.In short, this dissertation presents the main issues related to the context of steganography for 3D models. We discuss steganography for HDR images, and we explore the main applications making use of secret messages and their need of reliable, high-capacity techniques. Among these techniques, we restrict our work to blind steganographic schemes with high capacity, adaptability, and no distortion. These techniques are simple, efficient, and generalizable. Moreover, they are secure in the cryptographic sense. Because research in this field is growing and diversifying, a great deal of additional work is needed. Development in the area of steganography will continue. The novel and original ideas for steganographic applications we offer in this dissertation can benefit many applications in cryptography and copyright marking, as well. We hope that our work will inspire more research in these areas.