An image encryption algorithm based on new generalized fusion fractal structure

A robust and secure chaotic standard map based pseudorandom permutation-substitution scheme for image encryption

Image Encryption Algorithm based on Pseudo-random Sequence

Image data has been generated massively by devices in medical imaging modalities, cameras, and even by artificial intelligence. Encryption is the powerful method to keep the image content confidential, in which an encryption algorithm must include the confusion and diffusion properties. For massive images, a efficient method of encryption must be chosen to meet the demands of encryption speed and confidentiality. So far, chaos-based image encryption has been an active topic of research because it is considered an effective method to remove the correlation in image data as well as to keep confidential by the involvement of chaotic system in the encryption process. Besides, multiple image encryption algorithms encrypt multiple images in parallel, and it provides highly efficient performance in term of speed if it is implemented on a parallel computing platform such as multiple core processing as well as digital hardware design. Chaos-based multiple image encryption is constructed by integrating a chaotic system into multiple image encryption. Recently, many algorithms of chaos-based multiple image encryption have been proposed, and they are proved to have high efficient in terms of both speed and confidentiality. However, all the existing algorithms of chaos-based multiple image encryption require images of the same size and of the same number of bits representing pixels. Further, they encrypt a cohort of plain images at the same time, and all ciphertext images of a cohort must also be decrypted at the same time. It means that if it does not allow to decrypt one or some selected ciphertext images from a cohort separately; and as a result, it wastes time and energy to decrypt unwanted images. In this paper, three novel structures of chaos-based multiple image encryption are proposed which overcome the drawbacks of existing algorithms. That is, the proposed cryptosystems accept cohort images of different sizes; pixels of images can be represented by different numbers of bits; and any selected ciphertext images from a cohort can be decrypted separately. The security is improved by using the session keys of image-content dependency. The proposed structures of multiple image encryption consist of permutation, substitution, and diffusion processes. The difference between three structures is the order of such processes. A perturbed chaotic map and a linear-feedback shift register are employed to generate pseudo-random bit sequences for session keys. The simulation results for the exemplar designs using the proposed structures show the effectiveness by means of the statistical analysis for the session keys using the NIST randomness test, information entropy, histogram, and correlation coefficients of adjacent pixels in ciphertext images, and security analysis by means of space and sensitivity of the secret key. The hardware implementation on the FPGA platform demonstrates the feasibility of the proposed structures by means of throughput and hardware efficiency.

Transmission of the information in any form requires security. Security protocols used for communication rely on the use of random numbers. Pseudo-random numbers are required with good statistical properties and efficiency. The use of a single chaotic map may not produce enough randomness. The turbulence is padded into the existing map to improve its chaotic behaviour and increase the periodicity. A Pseudo-random number generator (PRNG) with this architecture is devised to generate random bit sequences from secret keys. The statistical properties of newly constructed PRNG are tested with NIST SP 800–22 statistical test suite and were shown to have good randomness. To ensure its usability in cryptographic applications, we analysed the size of its key space, key sensitivity, and performance speed. The test results show that the newly designed PRNG has a 3.6% increase in key space and a 5% increase in its performance speed compared to existing chaotic PRNGs. The novel PRNG with faster performance is found suitable for lightweight cryptographic applications.

This paper puts forward a novel image encryption algorithm that is based on permutation-diffusion architecture. In pixels' permutation stage, algorithm takes full advantage of the idea of magic cube's scrambling. There is only simple cyclic shift operation in each sub-block's permutation, but when the algorithm has disposed the current sub-block, the adjacent sub-blocks will be dealt with, too. In the cyclic shift of each row, stable points will help to decrease the correlation of adjacent pixels. To make encryption procedure uncertain, this paper brings in a parameter named delay-time that is generated by chaotic map. In the diffusion stage, by combining multiple operations and dynamic look-up table together, the proposed algorithm highly increases the uncertainty of the encryption procedure. At last, the experiment results of key space analysis, information entropy analysis, histogram analysis and etc. show that the encryption algorithm has well performance and it can be used in image encryption and transmission.

Image encryption is a hotspot of multimedia security. Many researchers adopted chaotic systems as pseudo-random number generators in image encryptions considering the properties of high sensitivity, large periodicity, low computation cost. Unpredictable, and etc. However, there is no deterministic approach to prove whether the way of using chaotic systems in an image encryption algorithm is secure or not. In this paper, a cryptanalysis is made to decipher a recent proposed chaotic JPEG image encryption algorithm by reforming the scrambled orders via correlation analysis, due to the improper use of chaotic sequence. Experimental results demonstrate the effectiveness of this method.

A novel chaotic image encryption algorithm based on content-sensitive dynamic function switching scheme

With the rapid growth of the volume of image data, the burden of storage and transmission has increased dramatically. However, current algorithms face challenges in balancing compression efficiency with security. In this paper, a novel algorithm for image compression and encryption utilizing an optimized BP neural network is proposed. First, the fireworks algorithm (FWA) is employed to optimize the initial weights of a BP network, bolstering image compression efficiency and reconstruction quality. Second, a variable-parameter chaotic system is constructed by combining Logistic-Tent and Chebyshev maps. Meanwhile, the pseudo-random sequences are generated by a variable-parameter chaotic system for scrambling and diffusion. Subsequently, a multi-level global-local scrambling mechanism is introduced to disrupt the statistical properties of the image. Finally, a Gray Code-based mutation-diffusion strategy is implemented to achieve encryption. Experimental results indicate that the encryption algorithm exhibits strong robustness in terms of histogram analysis, information entropy, key space, and attack resistance. At identical compression ratios, the proposed scheme proves superior to BP neural networks, delivering higher reconstruction quality for high-fidelity image recovery.

n Abstract - Partial encryption of images can be considered to be better than the existing image encryption techniques in the application areas where computational overhead is the main criterion. In this communication, a chaos based symmetric key partial encryption of gray level images has been proposed. In the proposed algorithm, the plain images, after decomposing them to bitplanes, are first classified into different categories. Next, a threshold based on the autocorrelation of blocks of different bitplanes is used to identify the significant and insignificant bit planes. Following this, the correlated bit planes of an image are encrypted with key stream sequences generated by a chaos based pseudo random binary number generator. The experimental results depict that the proposed algorithm can successfully encrypt and decrypt gray level images with secret keys. The simulation analysis also exhibits that the proposed method is loss­ less, secure and efficient in terms of several statistical tests, key sensitivity test, information entropy test and encryption quality tests. From the results it is observed that the new approach is able to hide the residual intelligence with lesser amount of time than that require for encrypting the entire image.

A new image encryption method based on memristive hyperchaos

A novel quantum gray-level image encryption and decryption algorithm based on image correlation decomposition is proposed. The correlation among image pixels is established by utilizing the superposition and measurement principle of quantum states. And a whole quantum image is divided into a series of sub-images. These sub-images are stored into a complete binary tree array constructed previously and then randomly performed by one of the operations of quantum random-phase gate, quantum revolving gate and Hadamard transform. The encrypted image can be obtained by superimposing the resulting sub-images with the superposition principle of quantum states. For the encryption algorithm, the keys are the parameters of random phase gate, rotation angle, binary sequence and orthonormal basis states. The security and the computational complexity of the proposed algorithm are analyzed. The proposed encryption algorithm can resist brute force attack due to its very large key space and has lower computational complexity than its classical counterparts.

This paper is introducing a new image encryption method using hyper chaos based keys, multi step group-based binary gray encryption, bit shifting logic and finally prepares a cipher image, an encrypted image recognizing the plaintext image is very next to impossible. The principal advantage of chaos base encryption is there are sequences of key for multiple times execution of the encryption process. Initially enormous Hyper-chaos numbers are to be generated considering a set of equation and finally generating a decimal key and bit shifting key using these Hyper-chaos numbers. These keys are the entity of the multi step group based binary gray conversion and bit shifting logic performed on every individual pixel of plain image. And lastly a set of comparison studies like histogram analysis, information entropy, correlation coefficient, sensitivity test of the pfoin image with cipher image have been run. The experimental results show the key space analysis and the security in the encryption algorithm It is shown here the encryption scheme deal with the bit-wise operation on the plain image pixel provides high performance on security and reliability, robustness and invisibility.

Image encryption based on chaotic maps is an important method for ensuring the secure communication of digital multimedia on the Internet. To improve the encryption performance and security of image encryption systems, a new image encryption algorithm is proposed that employs a compound chaotic map and random cyclic shift. First, a new hybrid chaotic system is designed by coupling logistic, ICMIC, Tent, and Chebyshev (HLITC) maps. Comparison tests with previous chaotic maps in terms of chaotic trajectory, Lyapunov exponent, and approximate entropy illustrate that the new hybrid chaotic map has better chaotic performance. Then, the proposed HLITC chaotic system and spiral transformation are used to develop a new chaotic image encryption scheme using the double permutation strategy. The new HLITC chaotic system is used to generate key sequences used in the image scrambling and diffusion stages. The spiral transformation controlled by the chaotic sequence is used to scramble the pixels of the plaintext image, while the XOR operation based on a chaotic map is used for pixel diffusion. Extensive experiments on statistical analysis, key sensitivity, and key space analysis were conducted. Experimental results show that the proposed encryption scheme has good robustness against brute-force attacks, statistical attacks, and differential attacks and is more effective than many existing chaotic image encryption algorithms.

Many fields need random and pseudorandom numbers, especially in cryptographic applications. d-bit segment binary pseudorandom numbers can be more easily used for block encryption. This paper studies on the statistical test for binary d string pseudorandom number generator (PRNG). Three postulates on the randomness for ideal pseudorandom d-bit segment sequences have been proposed. Based on the FIPS140-2 tests, a statistical test suite for d-bit segment sequences generated by PRNG has been proposed. Using the test suite tests the 100 key streams generated by RC4 PRNG and Matlab PRNG, respectively. The test results show that in the two 100 key streams generated via the two PRNGs with different seeds, about 97% 8-bit strings have passed the test suite, respectively. Using the key streams generated via the two PRNGs encrypts an RGB image. The results have shown that the encrypted RGB images have significant stream encryption avalanche effect.KeywordsInformation TheoryPseudorandom Number StringRandomness PostulateFIPS 140-2 TestNew Test Standard

This study introduces a cutting-edge image encryption algorithm aimed at elevating security standards. The Pan-Tompkins Algorithm (PTA) for key generation is proposed for the first time in this study. Additionally, employing steganography through the Least Significant Bit (LSB) method for embedding keys within the encrypted image enhances secure key distribution, thereby fortifying the encryption process. On the other hand, the integration of advanced algorithms, such as Zigzag scanning, the Affine Image Encryption Algorithm (AA), and the Vigenere Image Encryption Algorithm (VA), constitutes the fundamental innovation of the proposed image encryption algorithm. The proposed algorithm is named PanAAVA:Affine Algorithm and Vigenere Algorithm Encryption with PTA-Based Key Generation. The PanAAVA algorithm ensures unparalleled security by encrypting the positions and values of pixels using AA and VA. Notably, using PTA for key generation marks a distinctive and new key generation method feature of the algorithm. To assess the effectiveness of the PanAAVA, a comprehensive comparative analysis is conducted against well-established encryption methodologies, including Lena, Baboon, Airplane, and Pepper.The PanAAVA demonstrates exceptional proficiency in histogram analysis. The PanAAVA demonstrates a Unified Average Changing Intensity (UACI) of 33.4044%. Additionally, the Number of Pixels Change Rate (NPCR) is measured at 99.7442%, showcasing the algorithm’s effectiveness in inducing significant pixel changes. The proposed algorithm’s Mean Square Error (MSE) is calculated at 3.20679E5%. The proposed algorithm’s Peak Signal to Noise Ratio (PSNR) is recorded at 9.512475. The Key Space Size of the proposed algorithm is measured at 2209. Regarding correlation analysis, the PanAAVA achieves a high correlation score of 7.9996. The proposed algorithm successfully passes the National Institute of Standards and Technology (NIST) analysis, demonstrating a remarkably strong correlation close to 0 and a Structural Similarity Index Measure (SSIM) of 0.9977. Furthermore, regarding quantum communication, the proposed algorithm maintains stable key rates of 47.5 ± 0.8 kHz during the day and 50.9 ± 0.7 kHz at night. Additionally, PanAAVA achieves low Quantum Bit Error Rate (QBER) values of 4.77 ± 0.02, ensuring reliable and secure communication. The PanAAVA also demonstrates robust asymmetries at 49.81 ± 0.02 and 50.14 ± 0.03 for a crystal length of 20 mm. highlighting PanAAVA’s adaptability and effectiveness in different scenarios. PanAAVA outperforms other encryption algorithms concerning performance measurements and comparisons. In conclusion, the PanAAVA emerges as a beacon of superior security capabilities and innovation in image encryption, showcasing the potential to redefine standards in the field.