Real-time Secure Image Research Articles

Design and FPGA Implementation of a Hyper-Chaotic System for Real-time Secure Image Transmission

Recently, chaos theory has been widely used in multimedia and digital communications due to its unique properties that can enhance security, data compression, and signal processing. It plays a significant role in securing digital images and protecting sensitive visual information from unauthorized access, tampering, and interception. In this regard, chaotic signals are used in image encryption to empower the security; that's because chaotic systems are characterized by their sensitivity to initial conditions, and their unpredictable and seemingly random behavior. In particular, hyper-chaotic systems involve multiple chaotic systems interacting with each other. These systems can introduce more randomness and complexity, leading to stronger encryption techniques. In this paper, Hyper-chaotic Lorenz system is considered to design robust image encryption/ decryption system based on master-slave synchronization. Firstly, the rich dynamic characteristics of this system is studied using analytical and numerical nonlinear analysis tools. Next, the image secure system has been implemented through Field-Programmable Gate Arrays (FPGAs) Zedboard Zynq xc7z020-1clg484 to verify the image encryption/decryption directly on programmable hardware Kit. Numerical simulations, hardware implementation, and cryptanalysis tools are conducted to validate the effectiveness and robustness of the proposed system.

Integration of a novel 3D chaotic map with ELSS and novel cross-border pixel exchange strategy for secure image communication

This paper proposes a robust image encryption algorithm that utilizes a Novel three-dimensional (3D) Chaotic map and an Enhanced Logistic Sine System (ELSS). We leverage the unpredictability of 3D chaotic dynamics alongside the complexity of ELSS and DNA Sequence to forge a formidable image encryption scheme. Firstly, the image pixels are converted from decimal to hexadecimal notation and sorted in a 1D pixel array carrying a unique sequence of three channels of the RGB image. Secondly, the secret key is appended to XOR, the values with that 1-D pixels array. Thirdly, values are sorted by performing the binary right shift operation and encoded into DNA. Fourthly, a novel chaotic map is used to perform scrambling operations. Lastly, a novel enormous keyspace ELSS is used to perform efficient Border and Cross-Border (B &CB) pixel exchange, further enhancing the encryption quality of the proposed algorithm. Comprehensive security analysis proved that the proposed algorithm exhibits remarkable resilience against powerful known and chosen plaintext attacks and other prevalent cryptanalysis attacks, including differential attacks and exhaustive key search attacks. Henceforth, the proposed algorithm’s superior security and low computational cost make it an ideal choice for real-time secure image communication across various platforms, including satellite, multimedia, and military communications.

A symmetric image encryption scheme based on hybrid analog-digital chaotic system and parameter selection mechanism

In recent years, various chaos-based image encryption algorithms have been proposed to meet the growing demand for real-time secure image transmission. However, chaotic system that is the core component of chaos-based cryptosystem usually degrades under finite computing precision, causing many security issues. In this paper, a novel cryptosystem with analog-digital hybrid chaotic model is proposed. Firstly, the analog Chen chaotic system and the digital Logistic map are adopted to depict the capability of the hybrid model, in which analog system is used to perturb digital system. Dynamic analyses demonstrate that the hybrid method has better complexity, larger chaotic parameter range and good ability to counteract dynamical degradation. The chaos-based key streams generated by the perturbed Logistic map are more suitable for image encryption. Secondly, a parameter selection mechanism is introduced to increase security. The state variables of Chen chaotic system and cipher image are involved in parameter selection process to dynamically change the parameter of the perturbed Logistic map. The involvement of cipher image makes the key streams relevant to plain image and can resist known/chosen-plaintext attacks. Performance, security and comparison analyses indicate that this cryptosystem has high security, low time complexity, and ability to resist common attacks.

Secure image compression approach based on fusion of 3D chaotic maps and arithmetic coding

Advances in digital image processing and communications have created a great demand for real-time secure image transmission over the networks. However, the development of effective, fast and secure dependent image compression-encryption systems are still a research problem as the intrinsic features of images. A new approach is suggested in this study for partial image encryption-compression that adopts chaotic three-dimensional (3D) cat map to de-correlate relations among pixels in conjunction with an adaptive thresholding technique that is utilised as a lossy compression technique instead of using complex quantisation techniques and also as a substitution technique to increase the security of the cipher image. The proposed scheme is based on employing both of lossless compression with encryption on the most significant part of the image after contourlet transform. However, the least significant parts are lossy compressed by employing a simple thresholding rule and arithmetic coding to render the image totally unrecognisable. Due to the weakness of 3D cat map to chosen plain text attack, the suggested scheme incorporates a mechanism to generate random key depending on the contents of the image (context key). Several experiments were done on benchmark images to insure the validity of the proposed technique.

A chaos based image encryption algorithm using Shimizu-Morioka system

Recent research on image encryption schemes has focused on chaotic systems in order to meet the demand for real-time secure image transmission over the Internet. In this paper, we propose a new image encryption scheme based on ShimizuMorioka chaotic system. The scheme consists of two stages: the confusion (mixing) stage and the diffusion stage. In the confusion stage, we utilized the rich chaotic properties of the Shimizu-Morioka chaotic system by solving the system N time’s steps using Euler’s method and scrambled the positions of the pixel values of the image using the randomness of the solutions obtained from the chaotic system. In the diffusion stage, we generate N (where N is the size of image per colour) random integer numbers that is non-periodic and performed MOD and bitXOR operations on the shuffled image using the random numbers to obtain encrypted (diffused) image. The proposed algorithm is tested on a standard RGB image that is of size 256x256 and is stored with TIFF file format. Performance analysis on the proposed scheme such as the statistical analysis and the sensitivity analysis show that the proposed encryption scheme is reliable and strong enough to withstand different attacks.

An efficient and secure chaotic cipher algorithm for image content preservation

This paper proposes a new chaotic cipher algorithm for efficient and secure image content preservation, this method is specialized for both standard and medical images, and it consists of two modules which are iteratively performed: chaotic confusion and pixel diffusion. An improved 1D chaotic system (i.e., Logistic Tent System (LTS)) is employed in both confusion and diffusion modules, where its initial conditions are dynamically generated and controlled by the external secret key and SHA-256 hash value of the plain image, conducted to random-like generating key-streams, elevated the sensitivity to small changes on the plain image, and hence ensured the immunity of the proposal against known/chosen plain image attacks. The confusion module is governed by a novel nonlinear bit-shuffling and circular-shifting technique, aiming to achieve bit balancing effect, mixing effect of the pixel value, and certain diffusion mechanism. The diffusion module is ruled by means of an improved XOR operation (eXOR), to further promote the sensitivity to plain image, and accelerate the diffusion mechanism of the overall cipher algorithm. Given that the diffusion mechanism with respect to pixel value mixing are contributed by the two modules, only one encryption round is needed to make a good combination between computational performance, and sufficient security. The obtained results indicate the high performance in terms of execution-time and security level of the proposed cipher algorithm, and validate its robustness against cryptographic attacks, and hence confirm its efficiency for real-time secure image transmission.

Exploiting self-adaptive permutation–diffusion and DNA random encoding for secure and efficient image encryption

This paper presents a solution for secure and efficient image encryption with the help of self-adaptive permutation–diffusion and DNA random encoding. The plain image is firstly converted to DNA sequence using random encoding rules, so as to disarrange the bit distribution of the plaintext. A self-adaptive permutation–diffusion procedure is subsequently introduced for further encryption. The quantization processes of the permutation and diffusion procedures are disturbed by the intrinsic features of the plaintext, with the introduced disturbances can be automatically retrieved in the decryption end. The security of the system originates from the plaintext-related quantization of the encryption process which makes the cryptosystem secure against plaintext attack. Besides, the reusability of the random variables can dramatically promote the efficiency of the cryptosystem, which renders great potential for real-time secure image applications.

An efficient image encryption scheme using lookup table-based confusion and diffusion

This paper presents a solution to satisfy the increasing requirement of real-time secure image transmission over public networks. The main advantage of the proposed cryptosystem is high efficiency. The confusion and diffusion operations are both performed based on a lookup table. Therefore, the time-consuming floating point arithmetic in chaotic map iteration and quantization procedures of traditional chaos-based image cipher can be avoided. Besides, this cryptosystem possesses satisfactory resistance to noise perturbation and loss of cipher data, which are inevitable and unpredictable in real-world channels. The channel disturbance and the deliberate damage from the opponents are both tolerated. The recovered image from the damaged cipher data has satisfactory visual perception. Simulations prove the advantages of the proposed scheme, which render it a good candidate for real-time secure image applications.

An efficient and robust image encryption scheme for medical applications

In this paper, we propose a novel full and selective chaos-based image encryption scheme suitable for medical image encryption applications. The proposed approach consists of several rounds, where each round is made up of two phases, a shuffling phase and a masking phase. Both phases are block-based and use chaotic cat maps to shuffle and mask an input image. To improve the speed of the proposed scheme while maintaining a high level of security, the scheme employs a pseudorandom matrix, of the same size as the input image, in the masking phase of each round. Blocks of this pseudorandom matrix are permuted in each round of the shuffling phase according to the outputs of some chaotic maps. The proposed scheme applies mixing between blocks of the image in order to prevent cryptanalytic attacks such as differential attacks. Simulation results demonstrate high performance of the proposed scheme and show its robustness against cryptanalytic attacks, thus confirming its suitability for real-time secure image communication.

A Symmetric Image Encryption Scheme Base on Hyperchaotic System

In recent years, chaos-based image encryption technologies have been widely studied to meet the increasing demand for real-time secure image transmission applications. To overcome the drawbacks of small key space and weak security in many existing schemes based on low-dimensional chaotic maps, this paper suggests a security improved scheme with a permutation-diffusion architecture. In the permutation stage, baker map is employed to shuffle the pixel positions. In the diffusion stage, the value of each pixel is altered by using a key stream derived from hyperchaotic system. Compared with ordinary chaotic systems, hyperchaotic systems, with more complex dynamical behaviors and number of system variables, offer greater potential for secure cryptosystem construction. Extensive security analysis has been performed on the proposed scheme, including the most important ones like key space analysis, statistical analysis and key sensitivity, which has demonstrated the satisfactory security of the proposed scheme.

A fast chaos-based image encryption scheme with a dynamic state variables selection mechanism

In recent years, a variety of chaos-based image cryptosystems have been investigated to meet the increasing demand for real-time secure image transmission. Most of them are based on permutation–diffusion architecture, in which permutation and diffusion are two independent procedures with fixed control parameters. This property results in two flaws. (1) At least two chaotic state variables are required for encrypting one plain pixel, in permutation and diffusion stages respectively. Chaotic state variables produced with high computation complexity are not sufficiently used. (2) The key stream solely depends on the secret key, and hence the cryptosystem is vulnerable against known/chosen-plaintext attacks. In this paper, a fast chaos-based image encryption scheme with a dynamic state variables selection mechanism is proposed to enhance the security and promote the efficiency of chaos-based image cryptosystems. Experimental simulations and extensive cryptanalysis have been carried out and the results prove the superior security and high efficiency of the scheme.

A fast chaos-based symmetric image cryptosystem with an improved diffusion scheme

In recent years, a number of chaos-based image cryptosystems have been proposed to meet the increasing demand for real-time secure image transmission. In this paper, an improved diffusion scheme named continuous diffusion strategy is proposed to promote the efficiency of the conventional permutation–diffusion type image cipher. The new scheme contains a supplementary diffusion procedure after the conventional diffusion process and the control parameters are altered by the cipher image after the first diffusion procedure. As a result, the difference can be introduced at the beginning and spread out to the whole image, and hence the same level of security can be achieved with fewer overall rounds. Moreover, to further enhance the confusion effect of the diffusion operation, an intensive diffusion approach is proposed, using stretched key stream elements to perform a cyclic shift to the cipher pixels. Extensive cryptanalysis has been performed using differential analysis, key space analysis, key sensitivity analysis and various statistical analyses. Experiment results demonstrate that the new scheme has a high level of security and fast encryption speed for practical image encryption.

An improved permutation-diffusion type image cipher with a chaotic orbit perturbing mechanism

During the past decades, chaos-based permutation-diffusion type image cipher has been widely investigated to meet the increasing demand for real-time secure image transmission over public networks. However, the existing researches almost exclusively focus on the improvements of the permutation and diffusion methods independently, without consideration of cooperation between the two processes. In this paper, an improved permutation-diffusion type image cipher with a chaotic orbit perturbing mechanism is proposed. In the permutation stage, pixels in the plain image are shuffled with a pixel-swapping mechanism, and the pseudorandom locations are generated by chaotic logistic map iteration. Furthermore, a plain pixel related chaotic orbit perturbing mechanism is introduced. As a result, a tiny change in plain image will be spread out during the confusion process, and hence an effective diffusion effect is introduced. By using a reverse direction diffusion method, the introduced diffusion effect will be further diffused to the whole cipher image within one overall encryption round. Simulation results and extensive cryptanalysis justify that the proposed scheme has a satisfactory security with a low computational complexity, which renders it a good candidate for real-time secure image storage and distribution applications.

PARTIAL ENCRYPTION OF COMPRESSED VIDEO

The traffic of digital images and video has grown rapidly in the internet. Security becomes important for several applications like military image database, confidential video conferencing. Real-time secure image and video communication is challenging due to the processing time and computational requirement for encryption and decryption. Also the speed of most internet connections is very limited so the amount of data to be transmitted must be reduced. In this research, we shall introduce partial encryption technique on compressed images and videos. Another algorithm decomposes images into several different parts. We apply encryption algorithm to encrypt only the crucial parts, which are considerably smaller than original image, which result in significant reduction in processing time and computational requirement for encryption and decryption as well as reduce the bit rate and bandwidth requirement.

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

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.

A novel chaos-based bit-level permutation scheme for digital image encryption

Confidentiality is an important issue when digital images are transmitted over public networks, and encryption is the most useful technique employed for this purpose. Image encryption is somehow different from text encryption due to some inherent features of image such as bulk data capacity and high correlation among pixels, which are generally difficult to handle by conventional algorithms. Recently, chaos-based encryption has suggested a new and efficient way to deal with the intractable problems of fast and highly secure image encryption. This paper proposes a novel chaos-based bit-level permutation scheme for secure and efficient image cipher. To overcome the drawbacks of conventional permutation-only type image cipher, the proposed scheme introduced a significant diffusion effect in permutation procedure through a two-stage bit-level shuffling algorithm. The two-stage permutation operations are realized by chaotic sequence sorting algorithm and Arnold Cat map, respectively. Results of various types of analysis are interesting and indicate that the security level of the new scheme is competitive with that of permutation–diffusion type image cipher, while the computational complexity is much lower. Therefore the new scheme is a good candidate for real-time secure image communication applications.

A Novel Chaos-based Image Encryption Scheme with an Improved Permutation Process

Confidentiality is an important issue when digital images are transmitted over public networks, and encryption is the most useful technique employed for this purpose. Image encryption is somehow different from text encryption due to some inherent features of image such as bulk data capacity and high correlation among adjacent pixels, which are generally difficult to handle by conventional algorithms. Recently, chaos-based encryption has suggested a new and efficient way to deal with the intractable problems of fast and highly secure image encryption. This paper proposes a chaos-based cryptosystem with a novel permutation process for secure and efficient image protection. To improve the security of the confusion module, an improvement is made to the conventional confusion-diffusion architecture by introducing a certain diffusion mechanism in confusion stage through a lightweight bitlevel permutation algorithm. As a result, the diffusion performance is significantly enhanced and hence the overall security of the image cryptosystem is promoted. Results of various types of analysis indicate that the proposed scheme provides a good balance between security and speed and hence suitable for real-time secure image communication applications.

Single Core Hardware Module to Implement Partial Encryption of Compressed Image

Problem statement: Real-time secure image and video communication is challenging due to the processing time and computational requirement for encryption and decryption. In order to cope with these concerns, innovative image compression and encryption techniques are required. Approach: In this research, we have introduced partial encryption technique on compressed images and implemented the algorithm on Altera FLEX10K FPGA device that allows for efficient hardware implementation. The compression algorithm decomposes images into several different parts. We have used a secured encryption algorithm to encrypt only the crucial parts, which are considerably smaller than the original image, which result in significant reduction in processing time and computational requirement for encryption and decryption. The breadth-first traversal linear lossless quadtree decomposition method is used for the partial compression and RSA is used for the encryption. Results: Functional simulations were commenced to verify the functionality of the individual modules and the system on four different images. We have validated the advantage of the proposed approach through comparison, verification and analysis. The design has utilized 2928 units of LC with a system frequency of 13.42MHz. Conclusion: In this research, the FPGA prototyping of a partial encryption of compressed images using lossless quadtree compression and RSA encryption has been successfully implemented with minimum logic cells. It is found that the compression process is faster than the decompression process in linear quadtree approach. Moreover, the RSA simulations show that the encryption process is faster than the decryption process for all four images tested.

A new substitution–diffusion based image cipher using chaotic standard and logistic maps

In this paper, we propose a new loss-less symmetric image cipher based on the widely used substitution–diffusion architecture which utilizes chaotic standard and logistic maps. It is specifically designed for the coloured images, which are 3D arrays of data streams. The initial condition, system parameter of the chaotic standard map and number of iterations together constitute the secret key of the algorithm. The first round of substitution/confusion is achieved with the help of intermediate XORing keys calculated from the secret key. Then two rounds of diffusion namely the horizontal and vertical diffusions are completed by mixing the properties of horizontally and vertically adjacent pixels, respectively. In the fourth round, a robust substitution/confusion is accomplished by generating an intermediate chaotic key stream (CKS) image in a novel manner with the help of chaotic standard and logistic maps. The security and performance of the proposed image encryption technique has been analyzed thoroughly using various statistical analysis, key sensitivity analysis, differential analysis, key space analysis, speed analysis, etc. Results of the various types of analysis are encouraging and suggest that the proposed image encryption technique is able to manage the trade offs between the security and speed and hence suitable for the real-time secure image and video communication applications.

Partial encryption of compressed images and videos

The increased popularity of multimedia applications places a great demand on efficient data storage and transmission techniques. Network communication, especially over a wireless network, can easily be intercepted and must be protected from eavesdroppers. Unfortunately, encryption and decryption are slow, and it is often difficult, if not impossible, to carry out real-time secure image and video communication and processing. Methods have been proposed to combine compression and encryption together to reduce the overall processing time, but they are either insecure or too computationally intensive. We propose a novel solution called partial encryption, in which a secure encryption algorithm is used to encrypt only part of the compressed data. Partial encryption is applied to several image and video compression algorithms in this paper. Only 13-27% of the output from quadtree compression algorithms is encrypted for typical images, and less than 2% is encrypted for 512/spl times/512 images compressed by the set partitioning in hierarchical trees (SPIHT) algorithm. The results are similar for video compression, resulting in a significant reduction in encryption and decryption time. The proposed partial encryption schemes are fast, secure, and do not reduce the compression performance of the underlying compression algorithm.