a hierarchical protocol for increasing the stealthiness of steganographic methods
We present a new protocol that works in conjunction with information hiding algorithms to systematically improve their stealthiness. Our protocol is designed to work with many digital object types including natural language text, software, images, audio, or streaming data. It utilizes a tree-structured hierarchical view of the cover object and determines regions where changes to the object for embedding message data would be easily revealed by an attacker, and are thus to be avoided by the embedding process.The protocol requires the existence of a heuristic detectability metric which can be calculated over any region of the cover object and whose value correlates with the likelihood that a steganalysis algorithm would classify that region as one with embedded information. By judiciously spreading the effects of message-embedding over the whole object, the proposed protocol keeps the detectability of the cover object within allowable values at both fine and coarse scales of granularity. Our protocol provides a way to monitor and to control the effect of each operation on the object during message embedding.
steganalysis upper bound on detectability statistical attacks quad-tree structure steganography digital watermarking