Robust image encryption algorithm in dwt domain

Over the past few years, the use of chaotic maps have surfaced to become an important topic in the field of image encryption. The majority of chaos-based algorithms employed single or multiple rounds of confusion and diffusion. However, such algorithms increase the security and computational cost of the encryption process. On the other hand,a higher computational process is required to maintain security. To overcome this issue, a robust image encryption method using the features of two dimensional coupling map (2D-CM) and Discret Wavelet Transform(DWT) is proposed. Additionally, low-frequency component of DWT used for encryption can significantly save storage space thereby reducing computational overheads without compromising the security of the encryption. Finally, the cover image is combined with higher frequency coefficients to obtain the whole image, which will be totally secure against external attacks. The proposed encryption technique undergoes various security analyses, including Information Entropy (Ien)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(I_{en})$$\end{document}, Correlation Coefficients (CC), Number of Pixel Change Rate (NPCR), Unified Average Change Intensity (UACI) and computational complexity and histogram analysis. The NPCR value and UACI obtained for all the images under simulation are greater than 99% and 33, respectively. Furthermore, results show that the proposed method has low correlation, high key sensitivity and sufficient key space (2256)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(2^{256})$$\end{document} to withstand against external attacks.