Secure Steganography using the Most Significant Bits

摘要

The goal of steganography is to embed a hidden message in a cover. Typical covers are audio and image files and use the least significant bits to hide the message. Steganalysis is the classification of files as stego-bearing or not. Many techniques exist using statistical analysis to classify files and rely on the fact that hidden messages tend to be hidden in the low order bits and this upsets the distribution of ones and zeros in a detectable way. This paper will explore using the most significant bits for hiding the message without changing the cover file and changing the distribution of bits. The authors explore the maximum length of a message that can be found in the high order bits using a masking technique. Instead of changing bits in a message we mark the location of bits that make up the hidden message and transmit the mask as a separate file from the cover. The paper uses BMP image files to find the message and then coverts the images to JPEG for transmission. The receiver will then covert the file back to BMP format and extract the message. Small messages of up to approximately 2000 characters can easily be found and recovered using this method and will not be detected using standard steganalysis techniques.