Steganography via Codes for Memory with Defective Cells

摘要

Steganography is the art of covert (undetectable) communication in which secret data is embedded in innocuous looking messages by slightly modifying them. The detectability of secret data is influenced, besides other factors, by the placement of embedding changes within the message and by the embedding efficiency—the number of bits embedded per one embedding change. In this paper, we first show that codes for memory with defective cells enable steganographic communication without sharing the placement of embedding changes. This allows construction of a new class of steganographic schemes with improved security. We then describe an efficient coding method for memory with defective cells based on the LT process that is suitable for steganographic applications. In the second part of the paper, we explore a different approach based on random linear codes on small blocks with the goal to decrease the number of embedding changes. The embedding efficiency of this approach is compared to theoretically achievable bounds.