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Medical images make up for more than 25% of global attacks on privacy. Securing them is therefore of utmost importance. Chaos based image encryption is one of the most method suggested in the literature for image security due to their intrinsic characteristic, including ergodicity, aperiodicity, high sensitivity to initials conditions and system parameters. Dynamic systems such as bridge circuit, jerk circuit, Van der Pol circuit, Colpitts oscillator and many other pseudo-random numbers generators have been used in the process of encrypting images. Among them, are the jerk oscillators that have been used with different nonlinearities. In this paper, a new, simple, off-shell component of jerk oscillator (jerk quintic) with an interesting nonlinear function is proposed. Its dynamical behaviors are investigated using classical tools like bifurcation diagrams, Maximum Lyapunov exponent plot, basin of attraction, phase portraits. We showed that the nonlinear function is responsible of complex nonlinear behaviors displayed by the novel circuit, including symmetric/asymmetric bifurcation and coexisting bubbles, multistability just to name a few. The real implementation of the interesting circuit is embedded in a microcontroller verifies these dynamics. As an application of this contribution in multimedia, an encryption algorithm built on a new confusion-diffusion architecture using pseudo random number generated in high chaoticity regime of the new circuit is proposed. The cryptosystem underwent thorough security tests and proved to be fast thanks to the 3D map used, given its complex dynamical behaviors and large chaotic area. This approach yields a robust cipher that underwent thorough security tests better than the one in the literature like average NPCR=99.61, UACI=33.48, key space-sensitivity, entropy=7.9994, average correlation=0.0040. Furthermore, it proved to be robust in terms of noise and data loss in the transmission channel, offering a large key space of 10180 and an entropy close to the standard value, thus rendering the cryptosystem robust against various attacks, especially brute force and exhaustive attacks. [ABSTRACT FROM AUTHOR]

The heavy dependency of cryptography methods on mathematical theory and computational science necessitates the designing of a computationally secure cryptographic algorithm which is hard to break by an adversary. Matrix methods are intensively used in cryptography for their robustness and adaptability in the encryption of long messages but time complexity is a big concern while dealing with matrices of volumetric size. Further, the key generation function may limit the size of key domain which compromises the perfect security. Our work addresses these hindrances in priority to give an algorithm which is perfectly secure. This work contributes towards the matrix methods in cryptography; the two main attributes of a secured communication namely, true randomness of key selection and a liberty to extend the dimension of key space. [ABSTRACT FROM AUTHOR]

We proposed and verified a scheme of chaos synchronization for integrated five-section semiconductor lasers with matching parameters. The simulation results demonstrated that the integrated five-section semiconductor laser could generate a chaotic signal within a large parameter range of the driving currents of five sections. Subsequently, chaos synchronization between two integrated five-section semiconductor lasers with matched parameters was realized by using a common noise signal as a driver. Moreover, it was found that the synchronization was sensitive to the current mismatch in all five sections, indicating that the driving currents of the five sections could be used as keys of chaotic optical communication. Therefore, this synchronization scheme provides a candidate to increase the dimension of key space and enhances the security of the system. [ABSTRACT FROM AUTHOR]

The key expansion algorithm is an important part of any symmetric block cipher system since its effectiveness directly impacts the security of the entire block cipher; if it is not strong enough, the whole cryptosystem could be broken. Therefore, the round keys must be generated in a very secure way so that they cannot be attacked at all. Despite its great importance, cryptographic algorithm designers were not as interested in creating a secure round keys generation algorithm as they were in encryption itself. In this regard, designing a novel, simple, and flexible key expansion algorithm that generates round keys with secure characteristics is the aim of this research. The proposed Key Expansion algorithm is based on Dynamic Mealy Machine, 3D Logistic Map, and Protein Sequence (KE-DMM3DLMPS). The strength of the proposed KE-DMM3DLMPS algorithm is tested using flexibility, the NIST SP800-22 randomness test suite, histogram analysis, key space analysis, correlation coefficient, hamming distance, number of bit change rate, initial key sensitivity, confusion and diffusion, and differential attack. In comparison to some existing algorithms, experimental results showed that the generated round keys by the proposed KEDMM3DLMPS algorithm passed all the NIST tests with higher randomness, a uniform and ideal distribution of the amino acids present in each round key, and a higher key space of up to 20 x 2471. Furthermore, the KE-DMM3DLMPS avoids the linear relationship between the master secret key and the generated round keys and is capable of effectively blocking differential attacks. The proposed algorithm successfully adheres to key cryptographic principles such as irreversibility, independence, the strict avalanche effect, confusion, and diffusion. Through comprehensive testing and comparisons, the derived conclusion asserts that our algorithm stands as an efficient and secure solution. Its applicability extends to any symmetric block cryptosystem, with the primary goal of enhancing encryption and bolstering security. [ABSTRACT FROM AUTHOR]

Due to the importance of the NTRU public key cryptosystem, many improvements have been made to it by increasing security or speed to keep pace with the process of technological development in exchanging various data. In this paper, we construct a public key cryptosystem called HAQTR using non-commutative quaternion algebra with the change of the mathematical structure. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Computer Engineering & Applications is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We proposed and verified a scheme of chaos synchronization for integrated five-section semiconductor lasers with matching parameters. The simulation results demonstrated that the integrated five-section semiconductor laser could generate a chaotic signal within a large parameter range of the driving currents of five sections. Subsequently, chaos synchronization between two integrated five-section semiconductor lasers with matched parameters was realized by using a common noise signal as a driver. Moreover, it was found that the synchronization was sensitive to the current mismatch in all five sections, indicating that the driving currents of the five sections could be used as keys of chaotic optical communication. Therefore, this synchronization scheme provides a candidate to increase the dimension of key space and enhances the security of the system.

Chaotic secure communication schemes encounter a conflict of key space enhancement between the consistency and complexity of chaotic transceivers. In this paper, we propose a monolithically integrated multi-section semiconductor laser (MIMSL), used as a compact chaotic transceiver with an enhanced key space. The MIMSL consists of a distributed feedback (DFB) laser section, a semiconductor optical amplifier (SOA) section, two phase (P) sections and a passive optical waveguide. We simulate the dynamics of the MIMSL by applying the time-dependent coupled-wave equations for traveling-wave optical fields. Further, we numerically demonstrate a security enhancement of the unidirectional chaotic communication scheme using the MIMSL transceivers with independent high-speed modulation in the phase sections of the MIMSL. The security of our scheme depends not only on the difficulty of identifying the MIMSL structural parameters and the bias current of each section, but also on the phase shifts in two phase sections providing the additional dimension of security key space. Final simulation results show that a total of 248 key spaces can be achieved with a data rate of 2.5 Gb/s and an injection strength of 0.36. [ABSTRACT FROM AUTHOR]

With the widespread application of big data, the amount of data transmitted through optical networks has been increasing dramatically. Correlated random bit generation (CRBG) is one of the key technologies in secure communication systems to ensure security performance and transmission efficiency. We propose and demonstrate a CRBG scheme based on a Mach–Zehnder modulator (MZM) electro-optic feedback loop to improve the security and speed of communication systems. In this scheme, common-signal-induced synchronization is accomplished to generate wideband complex physical entropy sources, and a private hardware module is employed to perform post-processing and nonlinear transformation of the synchronized signal. The simulation results show that the effective bandwidth of the output chaotic signal is significantly increased to 27.76 GHz, and high-quality synchronization with a correlation coefficient of over 0.98 is reached. A high-rate CRBG of up to 5.3 Gb/s is successfully achieved between two synchronized wideband physical entropy sources, and the hardware key space is enhanced to ∼2 42 , which greatly improves the privacy of physical entropy sources. The proposed scheme provides a promising approach for high-speed private CRBG, which is expected to be used in high-speed secure key distribution and optical communication systems. [ABSTRACT FROM AUTHOR]

Cryptography is one of the most important security mechanisms for the transmission of digital media on the Internet. Most proposed cryptographic image methods based on chaotic maps are dependent upon image sizes and most of them worked on square images. In this paper for tackling this problem, a scale-invariant color image encryption method in three-dimensional space is presented. At first, the two-dimensional color image is converted into three-dimensional space, in this case, the red, green, and blue color spectrums are divided into a set of gray-level square sub-images. Then, to have confusion and diffusion properties, the 3D substitution and 3D permutation operation are performed on the sub-images. In substitution operations, the pixel values of the sub-images are changed with the help of XOR and circular shift operators with appropriate keys. In permutation operation, the position of the pixels is changed using modular three-dimensional chaos mappings. To have scale-invariant three-dimensional permutation, the sub-images are divided into one or more windows with equal size, and then 3D modular chaotic map operations are performed on each window with separate keys. Depending on the number of sub-images, there may be two last windows that have overlapping. To increase the speed of color image encryption, the steps of a 3D modular chaotic map on the windows can be implemented in parallel. The proposed approach relative to the similar color image encryption algorithms increases the key space and improves standard parameters, such as entropy, sensitivity, adjacent pixel correlations, and histogram uniformity.

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chaotic secure communication schemes encounter a conflict of key space enhancement between the consistency and complexity of chaotic transceivers. In this paper, we propose a monolithically integrated multi-section semiconductor laser (MIMSL), used as a compact chaotic transceiver with an enhanced key space. The MIMSL consists of a distributed feedback (DFB) laser section, a semiconductor optical amplifier (SOA) section, two phase (P) sections and a passive optical waveguide. We simulate the dynamics of the MIMSL by applying the time-dependent coupled-wave equations for traveling-wave optical fields. Further, we numerically demonstrate a security enhancement of the unidirectional chaotic communication scheme using the MIMSL transceivers with independent high-speed modulation in the phase sections of the MIMSL. The security of our scheme depends not only on the difficulty of identifying the MIMSL structural parameters and the bias current of each section, but also on the phase shifts in two phase sections providing the additional dimension of security key space. Final simulation results show that a total of 248 key spaces can be achieved with a data rate of 2.5 Gb/s and an injection strength of 0.36.

With the widespread application of big data, the amount of data transmitted through optical networks has been increasing dramatically. Correlated random bit generation (CRBG) is one of the key technologies in secure communication systems to ensure security performance and transmission efficiency. We propose and demonstrate a CRBG scheme based on a Mach–Zehnder modulator (MZM) electro-optic feedback loop to improve the security and speed of communication systems. In this scheme, common-signal-induced synchronization is accomplished to generate wideband complex physical entropy sources, and a private hardware module is employed to perform post-processing and nonlinear transformation of the synchronized signal. The simulation results show that the effective bandwidth of the output chaotic signal is significantly increased to 27.76 GHz, and high-quality synchronization with a correlation coefficient of over 0.98 is reached. A high-rate CRBG of up to 5.3 Gb/s is successfully achieved between two synchronized wideband physical entropy sources, and the hardware key space is enhanced to ∼242, which greatly improves the privacy of physical entropy sources. The proposed scheme provides a promising approach for high-speed private CRBG, which is expected to be used in high-speed secure key distribution and optical communication systems.

Several proposals of chaos-based algorithms have been proposed for secure communication and image encryption. In this paper, a new algorithm for colour image encryption has been proposed. The algorithm is based on a new 3-dimensional (3-D) discrete time chaos system which performs the diffusion and confusion processes. The novelty of the proposed work is the new 3-D map defined by five nonlinear terms and three control parameters to ensure better chaotic properties. Moreover, the proposed new map is used to perform 3-stage encryption algorithm which achieves better performance while preserving the traditional confusion-diffusion structure. Security analysis of the proposed algorithm is investigated and compared to some existing methods in terms of key space, metric entropy and correlation. Simulated results of our encryption algorithm prove its performance and suitability for colour image encryption. [ABSTRACT FROM AUTHOR]

Electrocardiogram (ECG) is essentially a significant physiological signal required in the diagnosis of cardiac disorders. For remote healthcare assistance, ECG signal along with patient's meta-data is communicated over the public network. During communication, security and privacy of patient's sensitive information is a major issue. Presently, a common steganography technique is being applied on the entire ECG signal. Since ECG signal consists of clinically more significant QRS regions as well as less significant non-QRS regions and employing same steganography approach on both the regions is not admissible. In this work, a hybrid approach is proposed for concealing the sensitive information in 2-dimensional (2D) ECG. A fusion of integer wavelet transform and modified least significant bit (IWT-mLSB) approach is applied in the pivotal QRS complex region; while pixel inverted pixel value differencing (PI-PVD) technique is implemented in the non-QRS region to hide the confidential data. The performance of the proposed algorithm is evaluated on standard as well as self-recorded database in terms of statistical parameters, clinically critical metrics, heart rate variability (HRV) analysis, embedding capacity (EC) and bit error rate (BER). The security of the proposed algorithm is further evaluated in terms of key space and key sensitivity. A comparative analysis with other state-of-the-art techniques exhibits the competency of the proposed technique. [ABSTRACT FROM AUTHOR]

In this article, we described specifics of pixels permutations based on the discretized, two-dimensional Chirikov standard map. Some properties of the discretized Chirikov map can be used by an attacker to recover the original images that are studied. For images with dimensions N ´ N the vulnerability of permutations allows for brute force attacks, and shown is the ability of an intruder to restore the original image without setting the value of keys permutations. Presented is also, successful cryptographic attack on the encrypted image through permutation of pixels. It is found that for images with dimension N ´ N the maximum number of combinations is equal to NN-1. A modified Chirikov map was proposed with improved permutation properties, due to the use of two nonlinearities, that increase the keys space to N2!.

Cryptography (encryption/decryption) is one of the prevailing mechanisms for protection of information (data or image) in the growing era of computerized exchange. It is the art of securing data/image by changing it into an unreadable format, called cipher text/image. Encryption mechanism is said to be efficient if it offers high security and robustness against attacks, and endow with very low correlation value between cipher and the original information. Enormous techniques and corresponding survey papers are available in literature considering only a few methods or parameters into account, but there is a stern need of investigation, which thoroughly considers vast variety of techniques and compares them in the light of numerous performance metrics under the influence of wide variety of probable threats. In view of the fact, this paper has taken account of almost all traditional, modern, chaotic, and quantum-chaotic based methods under the influence of prevalent intimidation and does a comprehensive investigation based on various performance metrics. To measure the efficacy, all the mechanisms are implemented in MATLAB-2014. Chaos and Quantum based algorithms are the superlative in comparison to others presented in literature under most of the extensive threats (attacks, noises etc.) and can resist brute force attacks due to large key space. In addition, suggestions for future scope have been given. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes an image encryption scheme using the combination of chaos, hyper-chaos, and DNA sequence operation. The proposed scheme performs three stages of encryption operations. Those are selection-level hyper-chaotic sequence based DNA-shuffling operation, key-image based DNA-diffusion operation, and hyper-chaotic sequence based DNA-shuffling operation. The advantages of this scheme are higher key space, higher confusion or randomness of pixels, higher sensitivity to the keys and plaintext pixels, stronger resistivity to the noises, and lossless encryption and decryption. Moreover, selection-level hyper-chaotic sequence based DNA-shuffling operation generates more complexities in the confusion process which increases the strength of encryptions and decryptions. The computer simulation and security analyses confirm the good encryption results of the proposed scheme and strong resistivity to the commonly used attacks. [ABSTRACT FROM AUTHOR]

Cryptography techniques are used to preserve the privacy and integrity of image media. Most proposed cryptographic images methods based on chaotic maps are dependent upon image sizes and most of them worked on square images. Tackling this problem, a scale invariant gray level image encryption method is proposed by means of 3D modular chaotic map. Initially, a 2D image with desirable size M × N is converted into a 3D image with m sub-images by size n × n. Optimizing the calculation, the parameters m and n should be appropriately selected. Having diffusion and confusion properties, two steps of 3D substitution and a 3D permutation step are used. In the 3D substitution steps, the pixels value of sub-images will be changed using the XOR operators and the circular shift. In the permutation step the pixels position of sub-images will be changed using 3D modular chaotic map, In this case, the m sub-images are divided into k = m n equal size windows which each window has n sub-images with size n × n, and the 3D modular chaotic map is performed on any window with independent parameters. Depending upon the value of m, the number of windows is greater than or equal to 1; for k > 1, the last two windows may overlap to perform 3D chaotic map operation. Accelerating the proposed encryption method, the 3D chaotic map operations on windows can be implemented in parallel. The proposed method, in comparison with other methods of image encryption, improves the statistical parameters of cryptographic analysis, key space, and speed. [ABSTRACT FROM AUTHOR]

In this advanced era, where we have high-speed connectivity, it is very imperative to insulate medical data from forgery and fraud. With the regular increment in the number of internet users, it is challenging to transmit the beefy medical data. This (medical data) is always reused for different diagnosis purposes, so the information of the medical images need to be protected. This paper introduces a new scheme to ensure the safety of the medical data, which includes the use of a chaotic map on the fractional discrete cosine transform (FrDCT) coefficients of the medical data/images. The imperative FrDCT provides a high degree of freedom for the encryption of the medical images. The algorithm consists of two significant steps, i.e., application of FrDCT on an image and after that chaotic map on FrDCT coefficients. The proposed algorithm discusses the benefits of FrDCT over fractional Fourier transform (FRFT) concerning fractional order α. The key sensitivity and space of the proposed algorithm for different medical images inspire us to make a platform for other researchers to work in this area. Experiments are conducted to study different parameters and challenges. The proposed method has been compared with state-of-the-art techniques. The results suggest that our technique outperforms many other state-of-the-art techniques. Graphical Abstract Overview of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a gray level image encryption method based on permutation operation and diffusion operation on image pixels. In diffusion operation, the image is subdivided into equal size sub-images, and the pixels of each sub-image are changed with the help of logical operators and circular shifts. In the permutation operation, the image is first divided into four bit-plate images, and the pixels of each bit-plate image are permuted in parallel by chaotic maps. In this research, reversible two-dimensional and three-dimensional chaotic maps based on modular mathematics are proposed to increase the key space, improve speed and period. The key space exponentially is increased as compared to standard chaotic maps through defining the reversibility in residue matrices, chaotic map in 3D space and changing the key in each round. In the proposed modular 3D chaotic map, the 2D image is first converted into 3D space, and then mapping operations are carried out for permuting the pixels into 3D space. The proposed encryption method for images improves the standard parameters of evaluation such as entropy, adjacent pixel correlations, histogram, and expanded key space. [ABSTRACT FROM AUTHOR]

Nowadays, internet is the medium through which people are sharing digital images. However, security is an issue in sharing of those images. Encryption techniques play an important role for the security of images. In this paper, an efficient colour image encryption scheme is proposed using multiple piece-wise linear chaotic map (PWLCM) systems. The proposed scheme first performs two-times multi-way block-based rotational permutation operations and then row-column rotational permutations. Finally, it performs row, column, and block diffusion operations. This scheme is simple and secure because it involves only simple rotational permutation operations using only PWLCM systems. Also, this scheme is efficient because it requires less computations and less simulation time to encrypt colour images. The advantages of this scheme are high key space, high security, simplicity and high efficiency in terms of computational complexity and simulation time. The simulation outputs and the security analyses indicate that the proposed method has better performance in terms of encryption efficiency, security, and resistivity for most of the common attacks. [ABSTRACT FROM AUTHOR]

Due to social networks, demand for sharing multimedia data is significantly increased in last decade. However, lower complexity and frequent security breaches on public network such as Internet make it easy for eavesdroppers to approach the actual contents without any hurdle. Many encryption algorithms has been developed by researchers to increase the security of such traffic and make it difficult for eavesdroppers to access actual data. However, these traditional algorithms increase the communication overhead, computational cost and also do not provide security against new attacks. These issues in recent algorithms motivate the researchers to further explore this area and proposed such algorithms which have lower overhead, more efficiency than the existing techniques and equip with requirements of next generations multimedia networks. To address all these issues and keeping in mind the future of next generation multimedia networks, we proposed a secure and light-weight encryption scheme for digital images. The proposed technique initially divide plaintext image in a number of blocks and correlation coefficients of each block are then calculated. The block with the maximum correlation coefficient values are pixel-wise XORed with the random numbers generated from a skew tent map based on a pre-defined threshold value. At last, the whole image is permuted via two random sequences generated from TD-ERCS chaotic map. Experimental results shows higher security via checking correlation, entropy, histogram, diffusion characteristic and key sensitivity of the proposed scheme. [ABSTRACT FROM AUTHOR]

Information security has become increasingly important with the rapid development of mobile devices and internet. An efficient encryption system is a key to this end. In this paper, we propose an image encryption method based on the cross diffusion of two chaotic maps. We use two chaotic sequences, namely the Logistic map and the Chebyshev map, for key generation which has larger security key space than single one. Moreover, we use these two sequences for further image encryption diffusion which decreases the correlation of neighboring pixels significantly. We conduct extensive experiments on several well-known images like Lena, Baboon, Koala, etc. Experimental results show that our algorithm has the characteristics of large key space, fast, robust to statistic attack, etc. [ABSTRACT FROM AUTHOR]

This paper proposes a quantum image encryption algorithm based on n-qubit normal arbitrary superposition state (NASS) by using the basic scheme of quantum transformation and random phase transformation. According to theoretical analysis and experimental simulation on MATLAB system, we find that key space is an important factor of encryption and decryption algorithm. When the secret key space is large, it is difficult for the attacker to crack the encrypted information. Based on this finding, we perform 2n + 4 times phase transformation in the encryption process. And each transformation is random, which increases the difficulty of decryption. So there are a total of 2n + 4 randomly transformed keys. In this paper, we design the implementation circuit of random phase transformation, and because the real quantum computer is not in our grasp, now we use MATLAB software to simulate grayscale image and color image encryption algorithm in classic computer, respectively. And the histogram, complexity and correlation are analyzed. Study shows that the proposed encryption algorithm is valid. [ABSTRACT FROM AUTHOR]