This paper aims to review the encountered technical contradictions when an attacker meets the cipher-images encrypted by the image encryption schemes (algorithms) proposed in 2018 from the viewpoint of an image cryptanalyst. The most representative works among them are selected and classified according to their essential structures. Almost all image cryptanalysis works published in 2018 are surveyed due to their small number. The challenging problems on design and analysis of image encryption schemes are summarized to receive the attentions of both designers and attackers (cryptanalysts) of image encryption schemes, which may promote solving scenario-oriented image security problems with new technologies.

When an attacker meets a cipher-image in 2018: A year in review

Image encryption techniques play a significant role in multimedia applications to secure and authenticate digital images. This paper presents a comprehensive study of various image encryption techniques. This paper covers the most significant developments in meta-heuristic based image encryption techniques. The various attacks and performance measures related to image encryption techniques have also been studied. The existing techniques are analyzed with respect to differential, statistical, and key analyses. The main goal of this paper is to give a broad perspective on characteristics of image encryption techniques. The paper concludes by discussing significant advancements in the field of image encryption and highlighting future challenges.

A Comprehensive Review on Image Encryption Techniques

This paper proposes a new chaotic image encryption scheme, which employs Josephus traversing and mixed chaotic map. The scheme consists of three processes: key stream generation process; three-round scrambling process; and one-round diffusion process. The proposed mathematical model is applied for the key stream generator in the first process. The initial values and parameters are sensitive to both the secret keys in the new scheme and plain images. The second process employs the Josephus traversing in scrambling; then the rows and columns of pixels are exchanged. The third process can modify the pixel gray-level values and crack the strong correlations between adjacent pixels simultaneously. The initial conditions for chaotic systems are derived using external secret keys by applying some algebraic transformations to the key. Security analysis indicates that the new scheme is effective, which can resist common attacks.

An Image Encryption Algorithm Based on Josephus Traversing and Mixed Chaotic Map

The fast image encryption algorithm based on lifting scheme and chaos

An optical image compression and encryption scheme based on compressive sensing and RSA algorithm

A symmetric key image cryptosystem based on the piecewise linear map is presented in this paper. In this cryptosystem, the encryption process and the decryption process are exactly same. They both include the same operations of plaintext-related scrambling once, diffusion twice and matrix rotating of 180 degrees four times. The length of secret key in the system is 64d where d is a positive integer. The proposed system can fight against the chosen/known plaintext attacks due to the using of plaintext-related scrambling. The simulate results and comparison analysis show that the proposed system has many merits such as high encryption/decryption speed, large key space, strong key sensitivity, strong plaintext sensitivity, strong cipher-text sensitivity, good statistical properties of cipher images, and large cipher-text information entropy. So the proposed system can be applied to actual communications.

Yingjun Tang

Papers

A plaintext-related image encryption algorithm based on chaos