In this paper,we first propose a memristive chaotic system and implement it by circuit *** chaotic dynamics and various attractors are analysed by using phase portrait,bifurcation diagram,and Lyapunov *** particular,t...
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In this paper,we first propose a memristive chaotic system and implement it by circuit *** chaotic dynamics and various attractors are analysed by using phase portrait,bifurcation diagram,and Lyapunov *** particular,the system has robust chaos in a wide parameter range and the initial value space,which is favourable to the security communication ***,we further explore its application in image encryption and present a new *** image processing,the external key is protected by the grain-128a algorithm and the initial values of the memristive system are updated with the plain *** not only perform random pixel extraction and masking with the chaotic cipher,but also use them as control parameters for Brownian motion to obtain the permutation *** addition,multiplication on the finite field GF(2^(8))is added to further enhance the ***,the simulation results verify that the proposed image encryption scheme has better performance and higher security,which can effectively resist various attacks.
Encryption is a very important way to secure data in storage and communication, and it is a process of encoding messages or information in such a manner that only authorised persons can access it. Different techniques...
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Encryption is a very important way to secure data in storage and communication, and it is a process of encoding messages or information in such a manner that only authorised persons can access it. Different techniques are used to protect confidential image data against illicit access. In image encryption using chaotic systems, most authors use or design algorithms to generate the initial parameters' values from the secret key. However, as the key size depends on the number of these parameters, the used algorithms show little sensitivity to small changes in the key. To enhance both security and sensitivity in the choice of the initial parameters, this work combines the use of the grain-128a stream cipher algorithm with two-dimensional Zaslavsky chaotic map. Firstly, the grain-128a algorithm is applied to generate the required parameters of Zaslavsky's chaotic map from a fixed length 256-bit secret key. Secondly, the sequences generated by the chaotic map are used to encrypt the image using a bit confusion and diffusion process. The simulation results on greyscale, colour, binary, indexed, and medical images together with the scores obtained in the evaluation of the algorithm show that the proposed method is very sure and effective in encrypting images of any size and any type.
HHL algorithm is a quantum algorithm for solving linear equation system. It can achieve an exponential improvement over the best classical algorithm. In this paper, we analyze the quantum security of grain-128/grain-1...
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HHL algorithm is a quantum algorithm for solving linear equation system. It can achieve an exponential improvement over the best classical algorithm. In this paper, we analyze the quantum security of grain-128/grain-128a stream cipher by using the HHL algorithm. Our algorithm is based on Chen and Gao's research on solving nonlinear equation system in Chen et al. (Quantum algorithm for optimization and polynomial system solving over finite field and application to cryptanalysis, 2018. arXiv:1802.03856) and Chen et al. (Quantum algorithms for Boolean equation solving and quantum algebraic attack on cryptosystems, 2017. arXiv:1712.06239). Firstly, we build a nonlinear Boolean equation system by choosing any keystream. Then, the nonlinear equation system is transformed into a special linear equation system that can be solved with the HHL algorithm. Finally, we solve the system by the HHL quantum algorithm. Our attack requires N > 2(8)-bit keystream, and the complexity is O(2(21) N-3.5 kappa(2) e(epsilon)/epsilon(0.5)) for grain-128, and O(2(21.5) N-3.5 kappa(2) e(epsilon)/epsilon(0.5)) for grain-128a where kappa is the condition number of the matrix of the corresponding linear systems and epsilon is a given error bound. Then we give a toy example of grain family to estimate kappa and briefly analyze the security of grain-128/grain-128a against HHL algorithm.
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