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Abstract: In recent years, a variety of chaos-based image cryptosystems have been studied. Most of them adopt the traditional confusion–diffusion architecture, which is considered insecure upon chosen/known plain-image attacks. In this paper, a nonlinear traverse on the plain-image using dependent diffusion and reverse cat map is proposed to replace the traditional linear traverse performed in the confusion phase. Two cryptosystems are designed and are implemented by software means. Simulation results and numerical analysis justify their high efficiency and sufficient strength. [Copyright &y& Elsevier]

Abstract: A distributed source coding scheme is proposed by incorporating a chaos-based cryptosystem in the Slepian–Wolf coding. The punctured codeword generated by the chaos-based cryptosystem results in ambiguity at the decoder side. This ambiguity can be removed by the maximum a posteriori decoding with the help of side information. In this way, encryption and source coding are performed simultaneously. This leads to a simple encoder structure with low implementation complexity. Simulation results show that the encoder complexity is lower than that of existing distributed source coding schemes. Moreover, at small block size, the proposed scheme has a performance comparable to existing distributed source coding schemes. [Copyright &y& Elsevier]

Abstract: One of the existing chaos-based image cryptosystems is composed of alternative substitution and diffusion stages. A multi-dimensional chaotic map is usually employed in the substitution stage for image pixel permutation while a one-dimensional (1D) chaotic map is used for diffusion purpose. As the latter usually involves real number arithmetic operations, the overall encryption speed is limited by the diffusion stage. In this paper, we propose a more efficient diffusion mechanism using simple table lookup and swapping techniques as a light-weight replacement of the 1D chaotic map iteration. Simulation results show that at a similar security level, the proposed cryptosystem needs about one-third the encryption time of a similar cryptosystem. The effective acceleration of chaos-based image cryptosystems is thus achieved. [Copyright &y& Elsevier]

Abstract: A novel chaotic hash algorithm based on a network structure formed by 16 chaotic maps is proposed. The original message is first padded with zeros to make the length a multiple of four. Then it is divided into a number of blocks each contains 4bytes. In the hashing process, the blocks are mixed together by the chaotic map network since the initial value and the control parameter of each tent map are dynamically determined by the output of its neighbors. To enhance the confusion and diffusion effect, the cipher block chaining (CBC) mode is adopted in the algorithm. Theoretic analyses and numerical simulations both show that the proposed hash algorithm possesses good statistical properties, strong collision resistance and high flexibility, as required by practical keyed hash functions. [Copyright &y& Elsevier]

Abstract: Recently, Xiao et al. proposed a novel key agreement protocol based on Chebyshev chaotic map. In this paper, the security of the protocol is analyzed, and two attack methods can be found in different scenarios. The essential principle of Xiao et al.’s scheme is summarized. It is also pointed out with proof that any attempt along this line to improve the security of Chebyshev map is redundant. [Copyright &y& Elsevier]

Abstract: Recently, a variety of chaos-based algorithms were proposed for image encryption. Nevertheless, none of them works efficiently in parallel computing environment. In this paper, we propose a framework for parallel image encryption. Based on this framework, a new algorithm is designed using the discretized Kolmogorov flow map. It fulfills all the requirements for a parallel image encryption algorithm. Moreover, it is secure and fast. These properties make it a good choice for image encryption on parallel computing platforms. [Copyright &y& Elsevier]

Abstract: In recent years, external key was introduced to chaotic cryptography by Pareek et al. and find its application in several discrete chaotic cryptosystems. The first part of this paper is devoted to the analysis of their essential weaknesses as well as some redundancies that contribute little to the security of those cryptosystems. Then, an improved scheme with all existing deficiencies and redundancies eliminated, is proposed. Theoretic analysis and numerical simulation both verify its superiority and security. [Copyright &y& Elsevier]

Abstract: In recent years, a variety of chaos-based digital image encryption algorithms have been suggested. Most of these algorithms implement permutations and diffusions at the pixel level by considering the pixel as the smallest (atomic) element of an image. In fact, a permutation at the bit level not only changes the position of the pixel but also alters its value. Here we propose an image cryptosystem employing the Arnold cat map for bit-level permutation and the logistic map for diffusion. Simulations have been carried out and analyzed in detail, demonstrating the superior security and high efficiency of our cryptosystem. [ABSTRACT FROM AUTHOR]

Abstract: A true random number generator (TRNG) makes use of a non-deterministic source to produce randomness. It is considered as more secure than a pseudorandom number generator as the degree of randomness is higher. In this letter, we propose a novel TRNG which generates random bits by moving the mouse casually. It is convenient, universal and low-cost for the personal computer (PC) platform. To eliminate the regular patterns of mouse movements caused by the habit of the same user, we propose three TRNGs based on chaotic hash functions. Experiments are conducted to evaluate the speed, diffusion and randomness performance of these TRNGs. The results show that two of them possess satisfactory performance and can be implemented on common PC platform. [Copyright &y& Elsevier]

Abstract: Based on the study of some existing chaotic encryption algorithms, a new block cipher is proposed. The proposed cipher encrypts 128-bit plaintext to 128-bit ciphertext blocks, using a 128-bit key K and the initial value and the control parameter mu of logistic map. It consists of an initial permutation and eight computationally identical rounds followed by an output transformation. Round r uses a 128-bit roundkey to transform a 128-bit input , which is fed to the next round. The output after round 8 enters the output transformation to produce the final ciphertext. All roundkeys are derived from K and a 128-bit random binary sequence generated from a chaotic map. Analysis shows that the proposed block cipher does not suffer from the flaws of pure chaotic cryptosystems and possesses high security. [Copyright &y& Elsevier]

Abstract: True random number generators are in general more secure than pseudo random number generators. In this paper, we propose a novel true random number generator which generates a 256-bit random number by computer mouse movement. It is cheap, convenient and universal for personal computers. To eliminate the effect of similar movement patterns generated by the same user, three chaos-based approaches, namely, discretized 2D chaotic map permutation, spatiotemporal chaos and “MASK” algorithm, are adopted to post-process the captured mouse movements. Random bits generated by three users are tested using NIST statistical tests. Both the spatiotemporal chaos approach and the “MASK” algorithm pass the tests successfully. However, the latter has a better performance in terms of efficiency and effectiveness and so is more practical for common personal computer applications. [Copyright &y& Elsevier]

Abstract: Based on the study of some existing chaotic encryption algorithms, a new block cipher is proposed. In the proposed cipher, two sequences of decimal numbers individually generated by two chaotic piecewise linear maps are used to determine the noise vectors by comparing the element of the two sequences. Then a sequence of decimal numbers is used to define a bijection map. The modular multiplication operation in the group and permutations are alternately applied on plaintext with block length of multiples of 64bits to produce ciphertext blocks of the same length. Analysis show that the proposed block cipher does not suffer from the flaws of pure chaotic cryptosystems. [Copyright &y& Elsevier]

Abstract: Recently, a new chaotic cryptosystem using external 128-bit key and multiple chaotic maps has been proposed. In this paper, a fundamental flaw of this cryptosystem is pointed out and a known plaintext attack is presented. Furthermore, a remedial modification is suggested, which avoids the flaw while keeping all the merits of the original cryptosystem. [Copyright &y& Elsevier]

The existence of the bifurcation and chaos is proved for the exponentially self-regulating population model. The conditions that the parameter must satisfy are also presented. It is shown that the equation enters the chaotic regime when the parameter exceeds a threshold. Finally, we calculate the values of the parameter corresponding to the superstable kneading sequences. [Copyright &y& Elsevier]

The security issues of symmetric ciphers based on DNA coding are studied in this paper. Firstly, ciphers solely based on DNA coding are described. Their operation principle is that a plain bit-string is mapped to a base-string according to a rule selected from eight possible ones. Then the base-string is processed with another secret base-string by one or more DNA operations such as XOR, addition and subtraction. Based on this framework, two basic models are constructed: to code at random or to employ a secret base-string. The security of these two models is analyzed. Secondly, two existing encryption schemes combining DNA coding and chaos theory are considered as the general models. Their security evaluations are presented in detail. It is believed that our security analyses help in the design of secure and efficient cryptosystems based on DNA coding. [ABSTRACT FROM AUTHOR]

Highlights: [•] A simple but secure chaotic cipher by improving the familiar permutation–diffusion structure is proposed. [•] Embedding a plaintext feedback technique into the permutation process to make the new scheme execute in a “one time pad” manner. [•] The plaintext/ciphertext feedback technique is employed to generate equivalent key dynamically in the diffusion part. [•] Experimental results show that the new scheme owns large key space and can resist the differential attack. [ABSTRACT FROM AUTHOR]

Abstract: Recently, Yu et al. presented a new cryptographic scheme based on delayed chaotic neural networks. In this letter, a fundamental flaw in Yu’s scheme is described. By means of chosen plaintext attack, the secret keystream used can easily be obtained. [Copyright &y& Elsevier]

It is well known that complex dynamic behaviors exist in time-delayed neural systems. Infinite positive Lyapunov exponents can be found in time-delayed chaotic systems since the dimension of such systems is infinite. However, theoretical and experimental models studied thus far are low dimensional systems with only one positive Lyapunov exponent. Consequently, messages masked by such chaotic systems are shown to be easily extracted in some cases. Therefore, communication system with a higher security level can be design by means of the time-delayed neuron systems. In this paper, we firstly investigate the dynamical behaviors of two-neuron systems with discrete delays. Then, the chaos synchronization in time-delayed neuron system is studied based on the method of designing the coupled system and employing Krasovskii–Lyapunov theory to search the synchronization conditions. Numerical results illustrate the correctness of our theoretical analyses. [Copyright &y& Elsevier]