Hiding a Covert Digital Image by Assembling the RSA Encryption Method and the Binary Encoding Method

Kuang Tsan Lin,Sheng Lih Yeh

doi:10.1155/2014/603659

Abstract

The Rivest-Shamir-Adleman (RSA) encryption method and the binary encoding method are assembled to form a hybrid hiding method to hide a covert digital image into a dot-matrix holographic image. First, the RSA encryption method is used to transform the covert image to form a RSA encryption data string. Then, all the elements of the RSA encryption data string are transferred into binary data. Finally, the binary data are encoded into the dot-matrix holographic image. The pixels of the dot-matrix holographic image contain seven groups of codes used for reconstructing the covert image. The seven groups of codes are identification codes, covert-image dimension codes, covert-image graylevel codes, pre-RSA bit number codes, RSA key codes, post-RSA bit number codes, and information codes. The reconstructed covert image derived from the dot-matrix holographic image and the original covert image are exactly the same.

Highlights

Image hiding methods can encode covert images in the space domain or in the spatial frequency domain
Hidden covert images can be reconstructed without any distortion usually, but their hiding security is lower often
Because spatial-frequency-domain encoding cases cannot reconstruct exact covert images, this paper will focus on space-domain encoding cases only

Summary

Introduction

Image hiding methods can encode covert images in the space domain or in the spatial frequency domain. For spatial-frequencydomain encoding cases, their hiding security is higher often, but there is more or less distortion for reconstructed covert images usually. Because spatial-frequency-domain encoding cases cannot reconstruct exact covert images, this paper will focus on space-domain encoding cases only Both higher security and higher noise-attack resistance are discussed here. The proposed method transforms a covert image with the RivestShamir-Adleman (RSA) encryption method and encodes the transformed data into a dot-matrix holographic image with the binary encoding method. Because the proposed hybrid hiding method possesses two layers of security (one layer is from the RSA encryption method and the other layer is from the binary encoding method), it can protect covert images very well. Covert image reconstruction does not cause image distortion

Theory

Experiments

Discussions

Conclusions