More Efficient Provably Secure Steganography

Steganography is the science of hiding the very presence of a secret message within a public communication channel. In Crypto 2002, Hopper, Langford, and von Ahn proposed the first complexitytheoretic definition and constructions of stegosystems. They later pointed out and corrected a flaw in one of their basic constructions. The correction, unfortunately, introduced a need for expensive errorcorrecting codes. We obtain a more efficient stegosystem by first analyzing the severity of the flaw in their original construction. As a result, for high-entropy channels, our construction is at least 5 times more efficient (in terms of rate) than their corrected version, and requires no computationally intensive error correcting.