Yong-feng Zhan

Bio: Yong-feng Zhan is an academic researcher from Northern Hospital. The author has contributed to research in topics: Encryption & Key space. The author has an hindex of 3, co-authored 3 publications receiving 356 citations.

A chaos-based digital image encryption scheme with an improved diffusion strategy.

Abstract: Chaos-based image cipher has been widely investigated over the last decade or so to meet the increasing demand for real-time secure image transmission over public networks. In this paper, an improved diffusion strategy is proposed to promote the efficiency of the most widely investigated permutation-diffusion type image cipher. By using the novel bidirectional diffusion strategy, the spreading process is significantly accelerated and hence the same level of security can be achieved with fewer overall encryption rounds. Moreover, to further enhance the security of the cryptosystem, a plain-text related chaotic orbit turbulence mechanism is introduced in diffusion procedure by perturbing the control parameter of the employed chaotic system according to the cipher-pixel. Extensive cryptanalysis has been performed on the proposed scheme using differential analysis, key space analysis, various statistical analyses and key sensitivity analysis. Results of our analyses indicate that the new scheme has a satisfactory security level with a low computational complexity, which renders it a good candidate for real-time secure image transmission applications.

An Efficient Medical Image Cryptosystem Based on Chaotic Maps

Abstract: With the growing applications of digital images in medical health system and the development of computer networks, medical image encryption has become an important technology to protect patients’ privacy when it is transmitted over open networks. Recently, chaos-based encryption approaches have been proven to be more effective for image encryption than other traditional methods (e.g. IDEA and AES). In this paper, we propose a novel chaos-based medical image cryptosystem with permutationdiffusion architecture, which provides efficient and secure transmissions for medical images over open networks. In the permutation stage, we introduce a novel shuffling method, which shuffles each pixel in plain image by exchanging it with a certain pixel selected by chaotic Logistic map. Compared with conventional permutation schemes based on Arnold cat map, Baker map and Standard map, the new scheme is superior in both key space and efficiency. In diffusion stage, each pixel is masked according to both key stream element and previous ciphered pixel so as to make the cryptosystem secure against differential attack. Intensive cryptanalysis is carried out and the experimental results demonstrate that the cryptosystem can withstand all kinds of known attacks, which includes brute-force attack, differential attack, known/chosen plain-text attack as well as various statistical attacks. Moreover, efficiency test indicates that the cryptosystem is efficient enough for real-time medical image protection applications.

Cascade Chaotic System With Applications

Abstract: Chaotic maps are widely used in different applications. Motivated by the cascade structure in electronic circuits, this paper introduces a general chaotic framework called the cascade chaotic system (CCS). Using two 1-D chaotic maps as seed maps, CCS is able to generate a huge number of new chaotic maps. Examples and evaluations show the CCS’s robustness. Compared with corresponding seed maps, newly generated chaotic maps are more unpredictable and have better chaotic performance, more parameters, and complex chaotic properties. To investigate applications of CCS, we introduce a pseudo-random number generator (PRNG) and a data encryption system using a chaotic map generated by CCS. Simulation and analysis demonstrate that the proposed PRNG has high quality of randomness and that the data encryption system is able to protect different types of data with a high-security level.