ABSTRACT
Steganography is the art of hiding a secret message in some kind of
media. The main goal is not to hide only the secret message but also the
existence of communication and secure data transferring. There are a lot of
methods that were utilized for building the steganography; such as LSB (Least
Significant Bits), Discrete Cosine Transform (DCT), Discrete Fourier Transform,
Spread-Spectrum Encoding, and Perceptual Masking, but all of them are
challenged by steganalysis. This paper proposes a new technique for Gray Scale Image
Steganography that uses the idea of image segmentation and LSB to deal with
such problem. The proposed method deals with different types of images by
converting them to a virtual gray scale 24 bitmaps, finds out the possible
segments inside image and then computes the possible areas for each segment
with boundaries. Any intruder trying to find the transformed image will not be
able to understand it without the correct knowledge about the transformation
process. The knowledge is represented by the key of image segmentation, key of
data distribution inside segment (area selection), key of mapping within each
area segment, key agreement of cryptography method, key of secret message
length and key of message extension. Our method is distinguishing oneself by
one master key to generate the area selection key, pixels selection keys and
cryptography key. Thus, the existence of secret message is hard to be detected
by the steganalysis. Experiment results show that the proposed technique
satisfied the main requirements of steganography; visual appearance,
modification rate, capacity, undetectability, and robustness against extraction
(security). Also it achieved the maximum capacity of cover image with a
modification rate equals 0.04 and visual quality for stego-image comparable to
cover image.