Hyper-chaotic Image Encryption Research Articles

A novel hyper-chaotic image encryption with sparse-representation based compression

This digital era uses lots of images in communication, which are confidential and large in volume. The transmission channel thus arises the question of security as well as transmission load. To date, several works are there to solve this issue. However, they fail to provide a single unit that gives these two facilities in a unified way. This paper presents a novel technique of unification of image compression and encryption in a single module via sparse-representation of image frames and hyper-chaotic encryption techniques. In this work, we have proposed a method to estimates the sparse vectors of a given image using a regularized trained over-complete dictionary and encrypt the non-zero coefficients of the sparse vectors using key-streams generated by a hyper-chaotic system. This sparse coding based encryption technique provides a higher compression ratio (CR) compared to some recently proposed techniques on one side and increases security level on the other side. Moreover, the security is strengthened by using this key-sequence in different steps in the encryption scheme. Thus the compressed-encrypted outputs are stronger than simple chaotic encryption against any intruder. The efficiency and authenticity of the proposed algorithm are verified through several quality-index e.g. entropy, CR, etc. The resistivity of the proposed algorithm toward the known or chosen-plaintext attack is also analyzed. The results of the key sensitivity test, and cropping attack test also ensure the authors’ claim. The comparison of the proposed technique with some recently published works justifies the reliability of this work.

Hyperchaotic image encryption algorithm based on bit-level permutation and DNA encoding

Many chaos-based image encryption algorithms using low-dimensional chaotic mapping and permutation diffusion structures have been proposed recently. However, low-dimensional chaotic maps are less secure than high-dimensional chaotic systems. Furthermore, the permutation process is independent of the plaintext and diffusion process. As a result, they are not very resistant to chosen plaintext attacks and chosen ciphertext attacks. In this paper, we propose a hyper-chaos-based image encryption algorithm that uses a 6-dimensional hyperchaotic system; the key stream generated by hyperchaotic system is related to the plaintext image. Then, bit-level permutation is employed to strengthen the security of the cryptosystem. Finally, DNA coding and operations are employed to change pixels. Theoretical analysis and numerical simulations demonstrate that the proposed algorithm is safe and reliable for image encryption.

Plaintext-related image encryption scheme using hyperchaotic system and DNA computing

We propose a hyperchaotic image encryption algorithm based on plaintext information and DNA computing. Compared to the traditional permutation-diffusion structure, the proposed method enhances the relationship between pixel position, gray value, and the plaintext image. First, the algorithm’s hyperchaotic system iteratively generates multiple pseudorandom matrices and globally scrambles the image position by operating on the pseudorandom matrices and plaintext information. Then, the pseudorandom matrices and the scrambled image are encoded into DNA sequences for subsequent algebraic operations, and a new vector is constructed to modulate the sequence to obtain robust encryption performance. Finally, the processed DNA sequence is decoded and a XOR operation is applied to the binary pseudorandom sequence to obtain a final cipher image. Based on the experimental results and security analysis, the proposed algorithm not only demonstrates excellent encryption but also resists various typical attacks.

A Novel Plaintext-Related Image Encryption Algorithm Based on Stochastic Signal Insertion and Block Swapping

Image encryption is an important method for protecting private data during communication. This paper proposes a novel hyperchaotic image encryption algorithm based on stochastic signal insertion and block permutation. First, the 5D hyperchaotic system is applied to generate pseudorandom number sequences. The SHA-256 hash function and secret keys are used to produce the initial values of the cryptosystem. The hash values can effectively enhance the sensitivity to plain image. To enlarge the key space and change orbit of cryptosystem, some stochastic signals are inserted during iteration. The plain image is equally divided into two parts. An X-coordinate, a Y-coordinate and a control table are established with produced pseudonumber sequences. The pixel is swapped with another pixel in the current block or another block depending on the control table. Cyclic shift is performed during the diffusion process. Performance and security analyses are executed to verify the effect of the proposed scheme. It is clear that the proposed scheme has a large key space and is highly sensitive to plain image and secret keys. Moreover, the cryptosystem has low computation complexity and can resist correlation analysis, entropy analysis, statistical attack, differential attack, noise and data loss attacks.

Cryptanalysis and Improvement of the Hyper-Chaotic Image Encryption Scheme Based on DNA Encoding and Scrambling

In recent years, hybrid chaotic image encryption schemes combined with the DNA encryption technology or other technologies have become a research focus of many researchers. However, some researchers neglect security analyses of proposed schemes under the chosen plaintext attack, therefore leaving security vulnerabilities. Considering this situation, we carefully investigate a recently reported hyper-chaotic image encryption scheme using the DNA encryption technology. In this paper, we first point out some issues identified in the reported scheme and make some necessary improvements, and then cryptanalyze it and propose a chosen plaintext attack algorithm. With the proposed attack algorithm, theoretical analyses and test results show that it can completely recover plain images without knowing any secure key related information. Finally, some suggestions for improving the security and practicability of the reported hyper-chaotic image encryption scheme are presented.

A Novel Hyperchaotic Image Encryption Scheme Based on DNA Encoding, Pixel-Level Scrambling and Bit-Level Scrambling

In this paper, a novel image encryption scheme has been proposed using pixel-level scrambling, bit-level scrambling, and DNA encoding. First, initial conditions of five-dimensional hyperchaotic system are computed and chaotic sequences are generated. Then, pixel-level scrambling and bit-level scrambling are implemented to permute the plain image. Permuted image and generated pseudorandom sequence are executed decomposition operations in order to enhance security. DNA encoding, DNA xor operation, and DNA complementary rules are also adopted to improve the security of the cryptosystem. Experiments results and theoretical analysis show that the proposed scheme is secure enough and can resist known plain text attack, statistical attacks, and differential attacks. It is suitable for practical application.

Secure image cryptosystem with unique key streams via hyper-chaotic system

This paper cryptanalyses the hyper-chaotic image encryption scheme developed by Norouzi et al. and presents a chosen-plain-image attack scenario to reveal its generated key stream. The recovered key stream can be used to decrypt any future related cipher-image without having the secret key. In addition, the paper introduces an advanced version of the underlying image encryption scheme to overcome its security shortcomings. Specifically, the proposed cipher generates a unique key stream for each distinct plain-image based on its fingerprint. This thwarts the chosen-plain-image attacks and enhances the security level of the proposed scheme. Finally, the experimental results confirm the robustness of the proposed image cipher against different types of attacks.

Cryptanalysis and improvement of a class of hyperchaos based image encryption algorithms

The security of a class of hyperchaotic image encryption algorithms is analysed. The results show that the shuffling process can be separated from the confusion process, and the formulas of encryption are simple, which makes the ciphertext cannot resist the attacks from chosen plaintext and ciphertext. Then we propose an improved and enhanced algorithm based on hyperchaos. The improved algorithm includes two rounds of encryption operation. The theoretical analyses and the experimental results indicate that the improved algorithm can overcome these flaws and has better cryptographic performances in resisting differential attacks and speed of encryption.

Cryptanalysis of a hyper-chaotic image encryption algorithm and its improved version

According to the Kerckhoff principle, a kind of image encryption algorithm based on hyper-chaos is discussed through choosing plaintext attack and ciphertext attack. The result shows that the key stream is independent of plaintext and one plain-text word is correlated with single cipher-text word for the algorithm, which makes the ciphertext decrypted easily with little computing by choosing plaintext and ciphertext attack. Considering the above problems, an improved algorithm based on hyper-chaos is proposed and the performance analysis is conducted, including statistical analysis, differential analysis, correlation analysis and key sensitivity testing. Theoretical analysis and simulation results show that the improved algorithm not only can resist the chosen plaintext attack and chosen ciphertext attack, but also can obtain better cryptographic properties, such as statistical characteristics, difference characteristics and so on.