Plaintext Sensitivity Research Articles

A novel conservative chaos driven dynamic DNA coding for image encryption

Recently, many image encryption algorithms based on hybrid DNA and chaos have been developed. Most of these algorithms utilize chaotic systems exhibiting dissipative dynamics and periodic windows/patterns in the bifurcation diagrams along with co-existing attractors in the neighborhoods of parameter space. Therefore, such algorithms generate several weak keys, thereby making them prone to various chaos- specific attacks. In this paper, we propose a novel conservative chaotic standard map-driven dynamic DNA coding (encoding, addition, subtraction and decoding) for image encryption. It is the first hybrid DNA and conservative chaos-based image encryption algorithm having effectively infinite key space. The proposed image encryption algorithm is a dynamic DNA coding algorithm i.e., for the encryption of each pixel different rules for encoding, addition/subtraction, decoding etc. are randomly selected based on the pseudorandom sequences generated with the help of the conservative chaotic standard map. We propose a novel way to generate pseudo-random sequences through the conservative chaotic standard map and also test them rigorously through the most stringent test suite of pseudo-randomness, the NIST test suite, before using them in the proposed image encryption algorithm. Our image encryption algorithm incorporates unique feed-forward and feedback mechanisms to generate and modify the dynamic one-time pixels that are further used for the encryption of each pixel of the plain image, therefore, bringing in the desired sensitivity on plaintext as well as ciphertext. All the controlling pseudorandom sequences used in the algorithm are generated for a different value of the parameter (part of the secret key) with inter-dependency through the iterates of the chaotic map (in the generation process) and therefore possess extreme key sensitivity too. The performance and security analysis has been executed extensively through histogram analysis, correlation analysis, information entropy analysis, DNA sequence-based analysis, perceptual quality analysis, key sensitivity analysis, plaintext sensitivity analysis, classical attack analysis, etc. The results are promising and prove the robustness of the algorithm against various common cryptanalytic attacks.

A secure image encryption algorithm based on hyper-chaotic and bit-level permutation

In this paper, an encryption algorithm based on hyper-chaotic system and bit-level permutation is proposed. Firstly, the forward diffusion method based on two-dimensional XOR operation is used to diffuse the image. Then, the scrambled images are arranged and scrambled in different directions. Finally, the ciphertext image is obtained by two-dimensional XOR backward diffusion. A novel bit-level permutation used in this algorithm, which not only expands the bit levels in different directions, but also exchanges the values between the bit bevels. It improves the efficiency and security of encryption. The diffusion random matrix is generated by hyperchaotic system. The initial value and control parameters of hyper-chaotic system are calculated by Secure Hash Algorithm 256 (SHA-256) function, which increases the key space and improves the plaintext sensitivity of the algorithm. On the one hand, the simulation results show that the scheme has high security and better plaintext sensitivity and key sensitivity. On the other hand, compared with the related algorithms, it can better resist statistical attacks and differential attacks.

A chaotic image encryption scheme based on multi-directional confusion and diffusion operations

A careful perusal of the literature regarding the image encryption algorithms indicates that many research articles based on pixel swapping operations in the horizontal and vertical orientations, have been published. This study ventures to develop a yet another sophisticated algorithm by extending the swapping operations along the diagonal–antidiagonal directions. Besides, unlike the previous studies, the confusion and diffusion operations over the pixels of the given input plain image have been crafted in a parallel fashion. This work has employed a 4D chaotic system to spawn the streams of random numbers. The initial values and the system parameters have been made dependent over the given plain image in order to inject the plaintext sensitivity in the proposed cipher. As a modus operandi of the proposed encryption algorithm, a non-intersecting pair of row and column is selected randomly with the same arbitrary length and swapped/XORed according to the value dictated by the random numbers. The same operations have been carried out for the non-intersecting pair of diagonal and anti-diagonal. The reason for selecting the non-intersecting pair stems from the fact that intersecting pairs cause to lose the precious pixels data which questions the potential invertibility feature of the proposed algorithm. To demonstrate the improved efficiency, ability to withstand the varied attacks by the cryptanalysis savvy, and prospects for some real-world application, the algorithm has been subjected to a comprehensive set of evaluation metrics.

High-quality restoration image encryption using DCT frequency-domain compression coding and chaos

With the arrival of the age of big data, the amount and types of data in the process of information transmission have increased significantly, and the full-disk encryption mode used by traditional encryption algorithms has certain limitations of the times. In order to further improve the bandwidth efficiency of digital images in the transmission process and the information effectiveness of digital image transmission, this paper proposes an algorithm of high-quality restoration image encryption using DCT frequency-domain compression coding and chaos. Firstly, the image hash value is used for the generation of an encryption key with plaintext correlation, then lightweight chaos is generated based on the key to obtain a pseudo-random sequence. Secondly, the image is partitioned into subblock, and converted from time domain into frequency domain by employing Discrete Cosine Transform (DCT) on each block, then perform quantization operation based on frequency domain information to obtain DCT coefficient matrix. Thirdly, the direct current (DC) coefficients and alternating current (AC) coefficients are extracted in the DCT coefficient matrix and compressed by different encoding methods to obtain two sets of bitstream containing DC coefficient and AC coefficient information. Fourthly, permute the DC coefficient bit stream by the chaotic sequence, and reconstruct it with the AC coefficient bit stream to obtain the frequency domain ciphertext image. Finally, the chaotic sequence is used to diffuse ciphertext, and the processed hash value is hidden in the ciphertext to obtain the final ciphertext. The theoretical and experimental analysis showed that the key length reaches 341 bits, and the PSNR value of the restored image is close to 60, all of which satisfy the theoretical value. Therefore, the algorithm has the characteristics of high compression rate, high-quality image restoration large key space, strong plaintext sensitivity, strong key sensitivity and so on. Our method proposed in this paper is expected to provide a new idea for confidential and secure communication in the age of big data.

A Novel Grayscale Image Encryption Scheme Based on the Block-Level Swapping of Pixels and the Chaotic System.

Hundreds of image encryption schemes have been conducted (as the literature review indicates). The majority of these schemes use pixels as building blocks for confusion and diffusion operations. Pixel-level operations are time-consuming and, thus, not suitable for many critical applications (e.g., telesurgery). Security is of the utmost importance while writing these schemes. This study aimed to provide a scheme based on block-level scrambling (with increased speed). Three streams of chaotic data were obtained through the intertwining logistic map (ILM). For a given image, the algorithm creates blocks of eight pixels. Two blocks (randomly selected from the long array of blocks) are swapped an arbitrary number of times. Two streams of random numbers facilitate this process. The scrambled image is further XORed with the key image generated through the third stream of random numbers to obtain the final cipher image. Plaintext sensitivity is incorporated through SHA-256 hash codes for the given image. The suggested cipher is subjected to a comprehensive set of security parameters, such as the key space, histogram, correlation coefficient, information entropy, differential attack, peak signal to noise ratio (PSNR), noise, and data loss attack, time complexity, and encryption throughput. In particular, the computational time of 0.1842 s and the throughput of 3.3488 Mbps of this scheme outperforms many published works, which bears immense promise for its real-world application.

A novel double image encryption algorithm based on coupled chaotic system

This paper constructs a two-dimensional Logistic-Sine-Henon map (2D-LSHM) for image encryption. By comparing with some existing chaotic systems, the 2D-LSHM has better chaotic performance and is more suitable for image encryption scenarios. Using the 2D-LSHM, we propose a double image adaptive encryption algorithm consisting of bit-level combinatorial permutation and four-directional adaptive diffusion called LSHM-DIAEA. Differently from traditional image encryption algorithms, the proposed LSHM-DIAEA can encrypt a color image and a grayscale image at the same time so that the information from each other can be fused and affected by each other, which makes the encryption process more secure and efficient. In addition, to enhance plaintext sensitivity, we introduce the secure hash algorithm-512 (SHA-512) and the Histogram of Oriented Gradient (HOG) feature extraction algorithm into the LSHM-DIAEA. Simulation and security analysis results illustrate that the LSHM-DIAEA provides a high security level to resist various cryptanalytic attacks and a high execution efficiency.

Chaos-Based Fast Image Encryption Scheme with Double Zigzag Permutation and Secure SHA256

Encryption is generally used to protect the content of images. This paper proposes a simple chaos-based color image encryption algorithm with permutation and diffusion stages dependent on the plain image to increase plain text sensitivity by collaboratively leveraging a sampled random noise signal, SHA-256, Henon chaotic map, double zigzag scanning and Lorenz system. Specifically, a hash value of the plain image and a sampled true random noise signal are generated using SHA-256 hash function and considered as an initial one-time key, which is then used to locate values from the sampled true random noise signal array to define the initial values and parameters for chaotic Henon map and Lorenz system. The Henon chaotic map creates an output that defines the starting point for double zigzag pixel scanning in the permutation stage, whereas the Lorenz system generates three sequences to diffuse the image’s three components; red, green, and blue using the XOR operation in order to get an encrypted image. Finally, statistical analysis results are offered to evaluate the complexity and ascertain security functionality for the proposed algorithm. Results show that the proposed image encryption algorithm is superior in comparison to other existing algorithms.

An efficient multi-level encryption scheme for stereoscopic medical images based on coupled chaotic system and Otsu threshold segmentation

This paper proposes an efficient multi-level encryption scheme for stereoscopic medical images based on coupled chaotic systems and Otsu threshold segmentation. In our method, first, the stereoscopic medical image is divided into the image top, middle, and lower parts. Moreover, each part is divided into background areas and regions of interest utilizing Otsu threshold segmentation, increasing about 40% the encryption efficiency when the background area is discarded. Second, compared with existing chaotic systems, the proposed coupled chaotic system has better ergodicity and randomness, with all NIST SP800-22 test data exceeding 0.01. Third, we develop a robust watermarking algorithm based on forwarding Meyer wavelet transform and singular value decomposition. Furthermore, the watermark algorithm embedded the two-dimensional code doctor-patient information in the region of interest. Finally, the experimental results demonstrate that the proposed algorithm has appealing encryption and watermark performance, the histogram and scatter graphs are governed by approximately uniform distribution, the NPCR and UACI of plaintext sensitivity and the key sensitivity are close to 99.6094% and 33.4635%, affording robustness to noise and clipping attacks.

Designing a double-way spread permutation framework utilizing chaos and S-box for symmetric image encryption

Recently, many chaos-based image cryptosystems have been investigated. However, some drawbacks of existing schemes are as follows: (1) the high computational complexity and bad scrambling effect of permutation algorithm reduce the security and practicality of the encryption system; (2) the insufficient association between encryption algorithm and plaintext makes it suffer from low plaintext sensitivity and inability to effectively resist chosen plaintext attack; (3) some algorithms are one-time-pad-like encryption systems, which reduce their practical value; (4) adequate plaintext relation elevates the plaintext sensitivity but also increases the ciphertext sensitivity of a cryptosystem and make it possess low robustness of defending noise and data loss attacks. To address the defects of existing works, a symmetric plaintext-related image cryptosystem based on a new scrambling framework using S-box is proposed. Firstly, substitution-box(S-box) of AES is first used to develop a new scrambling framework, namely double-way spread permutation framework (DWSPF), which can be used to scramble color images and gray images of any size. Then, the present study develops a new method of plaintext association that one parameter carried the information of original image and used to control the encryption process is padded to the encrypted array which is transmitted to the receiver. Such a strategy can realize the sufficient plaintext relation without the use of one-time-pad encryption technology and avoid high ciphertext sensitivity, which can well resist noise attacks and information loss attacks. Sufficient experiments results demonstrate that the proposed permutation framework and cryptosystem possess excellent security and efficiency compared with the state-of-art works.

A Novel and Fast Encryption System Based on Improved Josephus Scrambling and Chaotic Mapping.

To address the shortcomings of weak confusion and high time complexity of the existing permutation algorithms, including the traditional Josephus ring permutation (TJRP), an improved Josephus ring-based permutation (IJRBP) algorithm is developed. The proposed IJRBP replaces the remove operation used in TJRP with the position exchange operation and employs random permutation steps instead of fixed steps, which can offer a better scrambling effect and a higher permutation efficiency, compared with various scrambling methods. Then, a new encryption algorithm based on the IJRBP and chaotic system is developed. In our scheme, the plaintext feature parameter, which is related to the plaintext and a random sequence generated by a chaotic system, is used as the shift step of the circular shift operation to generate the diffusion matrix, which means that a minor change in the source image will generate a totally different encrypted image. Such a strategy strikes a balance between plaintext sensitivity and ciphertext sensitivity to obtain the ability to resist chosen-plaintext attacks (CPAs) and the high robustness of resisting noise attacks and data loss. Simulation results demonstrate that the proposed image cryptosystem has the advantages of great encryption efficiency and the ability to resist various common attacks.

Memristor-based time-delay hyperchaotic system with circuit simulation and image encryption

In present context, researchers have only found that memristor-based time-delay (MBTD) chaotic systems have rich dynamic behavior, but there are still many shortcomings in analyses and applications of MBTD chaotic systems. In this paper, relying on a memristor-based 4D chaotic system, by introducing delay parameters into this system, we not only find that the Lyapunov exponents (LEs) of the system change from one positive to multiple positive, i.e., the system changes from chaotic to hyperchaotic. And the coexistence of the system becomes more obvious. Although the circuit design of the delayed chaotic system is complex, the circuit implementation in Multisim is still given in this work. Ultimately, a novel digital image encryption algorithm based on this system is explained in details by introducing a hash algorithm. The proposed encryption algorithm, with strong robustness to external interference, good key sensitivity and good plaintext sensitivity, can handle images of different shapes, can effectively implement plaintext image encryption, and can resist differential attacks. All of the above further illustrate the advantages of the encryption algorithm and good randomness of the 4D MBTD hyperchaotic system.

A New V-Net Convolutional Neural Network Based on Four-Dimensional Hyperchaotic System for Medical Image Encryption

In the transmission of medical images, if the image is not processed, it is very likely to leak data and personal privacy, resulting in unpredictable consequences. Traditional encryption algorithms have limited ability to deal with complex data. The chaotic system is characterized by randomness and ergodicity, which has advantages over traditional encryption algorithms in image encryption processing. A novel V-net convolutional neural network (CNN) based on four-dimensional hyperchaotic system for medical image encryption is presented in this study. Firstly, the plaintext medical images are processed into 4D hyperchaotic sequence images, including image segmentation, chaotic system processing, and pseudorandom sequence generation. Then, V-net CNN is used to train chaotic sequences to eliminate the periodicity of chaotic sequences. Finally, the chaotic sequence image is diffused to change the raw image pixel to realize the encryption processing. Simulation test analysis demonstrates that the proposed algorithm has better effect, robustness, and plaintext sensitivity.

Novel and secure plaintext‐related image encryption algorithm based on compressive sensing and tent‐sine system

In this paper, a secure plaintext-related image encryption scheme based on compressive sensing and a tent-sine system is proposed. First, the discrete wavelet transform (DWT) is used to transform the plain image to get a coefficient matrix. Second, several chaotic sequences generated by the tent-sine chaotic map are used to scramble the coefficient matrix and construct a measurement matrix. Afterward, compressive sensing is performed on the coefficient matrix to obtain a small-sized encrypted image. Finally, an image encryption scheme related to plaintext is designed. In particular, the proposed system uses the original image information to participate in the encryption process, ensuring the high sensitivity of the cryptosystem to minor differences in the plain image and good performance on resisting known/selected plaintext attacks. Furthermore, to convey the plaintext-related parameters to the receiver, the dimension of the ciphertext image is expanded, and the parameters are embedded into the ciphertext image. Simulation results and security analysis show that the proposed image encryption system has strong plaintext sensitivity and robustness for effectively resisting various typical attacks such as brute-force attacks, statistical attacks, and differential attacks.

Fast Chaotic Image Encryption Algorithm Using a Novel Divide and Conquer Diffusion Strategy

To protect image privacy in real-time transmission, a fast chaotic image encryption algorithm using a novel divide and conquer diffusion strategy is proposed in this paper. Firstly, a fast pseudo-random sequence generator is constructed using 2D hyperchaotic systems. And by performing bitwise XOR operation between two integer sequences obtained from different systems, the final key stream used for diffusion will have better randomness and unpredictability. Secondly, to achieve divide and conquer diffusion, the plain image is divided into three parts, then a parallel CBC-based diffusion method can simultaneously act on upper and bottom parts (or left and right parts), which achieves a time complexity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {O}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W+H$ </tex-math></inline-formula> ). Moreover, within the diffusion process, the mechanism of information interaction on the central row or column further enhances avalanche effect to resist differential attack. Thirdly, the session key of the proposed algorithm is a mixture of the plain image’s hash value and a true random sequence, which not only improve plaintext sensitivity but also realize one-time pad. Finally, experimental results indicate the superiority of our algorithm to resist statistical, chosen-plaintext, entropy, and other common attacks. Furthermore, by comparison with previous works, our algorithm preforms much faster execution speed with only average of 0.08s to encrypt images of size <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$512\times 512$ </tex-math></inline-formula> , while it provide the same or even higher level of security. Therefore, the proposed algorithm can meet security and efficiency requirements of real-time communications of image data.

Data security using random dynamic salting and AES based on master-slave keys for Iraqi dam management system

In the present time, dam management is considered one of the important challenges for e-government in Iraq, becuase it needs information technology infrastructure, data integrity and protection of user privacy against Internet threats that render such vital infrastructure ineffective. This struggle between the proposed dam management system (DMS) and a multi-tier secure model specifically for the Fallujah dam (and generally for all dams) which is addressed in this paper as a case study. To do this, a relational database design will discuss the development of a multi-tier secure model for integration of the dam management framework with its functions. This paper will discusse encryption and decryption of the dam data using the advanced encryption standard (AES) algorithm with derived keys via PBKDF2 and RNG sequences generator and Slave key for salting protection. The experimental results and analysis on the speed of encryption/decryption process, entropy value, plain text sensitivity, key sensitivity, keyspaceanalysis and histogram analysis will prove the the proposed scheme can impede the known attacks like brute force attacks, statistical and differential.Thus, the encryption scheme can be implemented on the proposed DMS and any other information system, as the implementation which will be presented in the results.

Quantum logistic image encryption algorithm based on SHA-3 and RSA

This study proposes a quantum logistic image encryption algorithm based on the Rivest–Shamir–Adleman (RSA) and secure hash (SHA-3) algorithms. First, the asymmetric encryption algorithm RSA is used to randomly generate key pairs with private key and public key. A fixed matrix is then produced to confuse the plain image by additive modular operation and get preprocessed image. Second, the preprocessed image is computed by the hash function SHA-3 to obtain the plain message that is then stored secretly. Using RSA algorithm, the cipher message can be obtained corresponding to the plain message. After combining both the plain and cipher messages, the initial conditions of the quantum logistic map are calculated using a new mathematical model. Random keystream can then be generated from the quantum logistic map. Third, the keystream is further employed to cyclically confuse row and column pixels in the preprocessed image with different directions. Then, diffusion operations to odd row and odd column are carried out followed by even row and column, respectively. Finally, the cipher image can be reconstructed by both inverse cyclic confusion and inverse diffusion to each row and column. The test results show that the algorithm has strong plaintext sensitivity and key sensitivity as well as an enhanced ability to resist various cryptographic attacks. Therefore, the proposed algorithm is suitable for secure communication of network image in conjunction with a public cryptosystem.

Dynamic 3D scrambled image based RGB image encryption scheme using hyperchaotic system and DNA encoding

Hundreds of image encryption schemes based on the conventional 2D image space exist in the literature. Very few were built using the 3D image space. In this study, for better security, we present a new RGB (color image) encryption scheme based on the Dynamic 3D scrambled image (D3DSI), 5D multi-wing-hyperchaotic-system and DNA computing. After providing a color image as input, its three components are reshaped in a 1D array. These three components are concatenated to form a single 1D array. A 3D scrambled image with arbitrary dimensions is created. Pixels from the 1D array are shifted randomly to the different cells of the 3D scrambled image. Afterwards, for the realization of the diffusion effects, an XOR operation is performed between the key image and the 3D scrambled image. Next, the pixels data and the DNA key image are DNA-encoded. The pixels data in the form of DNA strands is once again scrambled using the same 3D scrambled image. Once again, the pixels data in DNA strands is XORed with the DNA-encoded key image. Lastly these DNA strands are transformed back to the decimal form. Out of this decimal form, three constituent color components, i.e., red, green and blue are separated and merged together to form the color cipher image. To obtain plaintext sensitivity, an image characteristic has been used to temper the one initial value of the chaotic map being used. The simulation results and the security analysis both portray better security, defiance to the varied threats and a real world applicability of the proposed image cipher.

A Novel Image Encryption Algorithm Based on the Delayed Maps and Permutation-Confusion-Diffusion Architecture

To improve the dynamical behaviors of 1D chaotic maps, a new linear-delay-modulation method (LDM) is proposed. Derived from the Sine map, a delayed Sine map (DSM) is proposed based on the LDM. Then, we substitute the Sine map in the SIMM system with DSM and obtained a delayed SIMM system (DSIMM). Its chaotic performance is analyzed through the phase diagram, Lyapunov exponent spectrum, and complexity. The results show that the delayed chaotic map can generate more complex dynamical behaviors and more random sequences. Hence, we apply the two delayed systems to a novel image encryption algorithm with the permutation-confusion-diffusion architecture. Firstly, to permutate the pixel of the image efficiently, the plain-image is scrambled by using a multilayer of the nonlinear index. Secondly, the image is confused by using the chaotic matrix generated with two chaotic sequences, and then, the ciphertext is transformed into a 1D sequence. Finally, to improve the plaintext sensitivity and facilitate key management, we enhance the sensitivity by applying a novel diffusion algorithm instead of using plaintext-related keystream. The diffusion equation contains the sum of undiffused pixels and the operation of cyclic bit-shift. Simulation results for the gray image illustrate the effectiveness of the proposed encryption algorithm.

A Residual Chaotic System for Image Security and Digital Video Watermarking

Multimedia data security has become a noticeable problem in the continuous development of multimedia technology. Traditional chaotic systems usually require larger bit-width iterative calculations to affect the generation rate of chaotic systems when generating. To solve this problem, we proposed a general Residual Chaotic System (RCS) for image security in heterogeneous multimedia signal processing environments. Based on the Residue Number System (RNS) commonly used in VLSI, we generate the general chaotic sequences by iterating unary polynomial function through it in Galois Field (GF). Moreover, we make use of the Box-Muller algorithm to generate RCS, which improved the speed of operation by a large margin when doing R/B backward transformation. Experiments show that the key sensitivity and plaintext sensitivity of the proposed encryption system are good, and the system can encrypt pictures efficiently and safely. Then, we proposed a watermark embedding and extraction algorithm with block selection. Based on the proposed new judgment conditions, the $4\times 4$ brightness blocks are divided into five categories, then the appropriate types of blocks are selected accordingly. After testing the performance indexes of cypher-text images, including statistical and sensitivity-related tests, all results indicate that our algorithm has good randomness and security. The invisibility is good, the watermark capacity has been significantly improved, and the video bit-rate growth rate is in a good range. The watermark can resist attacks such as noise and the bit error rate under re-encoding and Gaussian low-pass filtering attacks. Compared with other algorithms, the algorithm that we proposed is faster, much more efficient, and more secure. Therefore, it is a practical alternative scheme for heterogeneous communication environments.

On the Image Encryption Algorithm Based on the Chaotic System, DNA Encoding, and Castle

Hundreds of image encryption algorithms have been developed for the security and integrity of images through the combination of DNA computing and chaotic maps. This combination of the two instruments is not sufficient enough to thwart the potential threats from the cryptanalysis community as the literature review suggests. To inject more robustness and security stuff, a novel image encryption scheme has been written in this research by fusing the chaotic system, DNA computing and Castle—a chess piece. As the plain image is input, its pixels are shifted to the scrambled image at the randomly chosen pixel addresses. This scrambling has been realized through the routine called Image Scrambler using Castle (ISUC). Castle randomly moves on the hypothetical large chessboard. Pixels taken from the plain image are shifted to the addresses of the scrambled image, where Castle lands in each iteration. After the plain image is scrambled, it is DNA encoded. Two mask images are also DNA encoded. Then to throw the diffusion effects in the cipher, DNA Addition and DNA XOR operations between the DNA encoded pixels data and the DNA encoded mask images have been conducted. Next, the pixels data are converted back into their decimal equivalents. Four dimensional chaotic system has been used to get the chaotic vectors. The hash codes given by the SHA-256 function have been used in the cipher to introduce the plaintext sensitivity in its design. We got an information entropy of 7.9974. Simulation carried out through the machine, and the thorough security analyses demonstrate the good security effects, defiance to the varied attacks from the cryptanalysis community, and the bright prospects for some real world application of the proposed image cipher.