The Square Root Law in Stegosystems with Imperfect Information

摘要

Theoretical results about the capacity of stegosystems typically assume that one or both of the adversaries has perfect knowledge of the cover source. So-called perfect steganography is possible if the em-bedder has this perfect knowledge, and the Square Root Law of capacity applies when the embedder has imperfect knowledge but the detector has perfect knowledge. The epistemology of stegosystems is underdeveloped and these assumptions are sometimes unstated. In this work we consider stegosystems where the detector has imperfect information about the cover source: once the problem is suitably formalized, we show a parallel to the Square Root Law. This answers a question raised by Bohme.