Utilizing complex dynamics of chaotic maps and systems in encryption was studied comprehensively in the past two and a half decades. In 1989, Fridrich's chaotic image encryption scheme was designed ...by iterating chaotic position permutation and value substitution some rounds, which received intensive attention in the field of chaos-based cryptography. In 2010, Solak et al. proposed a chosen-ciphertext attack on the Fridrich's scheme utilizing influence network between cipher-pixels and the corresponding plain-pixels. Based on their creative work, this paper scrutinized some properties of Fridrich's scheme with concise mathematical language. Then, some minor defects of the real performance of Solak's attack method were given. The work provides some bases for further optimizing attack on the Fridrich's scheme and its variants.
•Some properties of Fridrich's chaotic image encryption scheme are represented with concise mathematical language.•Real performance of Solak's chosen-plaintext attack on Fridrich's chaotic image encryption scheme is tested with detailed experiments.•Extension of the attack idea to Chen's scheme and its variants is briefly evaluated.
The convection-diffusion equation is a fundamental equation that exists widely. The convection-diffusion equation consists of two processes: diffusion and convection. The convection-diffusion ...equation can also be called drift-diffusion equaintion. The convection – diffusion equation mainly characterizes natural phenomenon in which physical particles, energy are transferred in a system. The well-known linear transport equation is also one kind of convection-diffusion equation. The transport equation can describe the transport of a scalar field such as material feature, chemical reaction or temperature in an incompressible flow. In this paper, we discuss the famous numerical scheme, Lax-Friedrichs method, for the linear transport equation. The important ingredient of the design of the Lax-Friedrichs Method, namely the choice of the numerical fluxes will be discussed in detail. We give a detailed proof of the
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stability of the Lax-Friedrichs scheme for the linear transport equation. We also address issues related to the implementation of this numerical scheme.
This paper initiates a systematic methodology for generating various grid multiwing hyperchaotic attractors by switching control and constructing super-heteroclinic loops from the piecewise linear ...hyperchaotic Lorenz system family. By linearizing the three-dimensional generalized Lorenz system family at their two symmetric equilibria and then introducing the state feedback, two fundamental four-dimensional linear systems are obtained. Moreover, a super-heteroclinic loop is constructed to connect all equilibria of the above two fundamental four-dimensional linear systems via switching control. Under some suitable conditions, various grid multiwing hyperchaotic attractors from the real world applications can be generated. Furthermore, a module-based circuit design approach is developed for realizing the designed piecewise linear grid multiwing hyperchaotic Lorenz and Chen attractors. The experimental observations validate the proposed systematic methodology for grid multiwing hyperchaotic attractors generation. Our theoretical analysis, numerical simulations and circuit implementation together show the effectiveness and universality of the proposed systematic methodology.
Recently, an image encryption algorithm based on DNA encoding and spatiotemporal chaos (IEA-DESC) was proposed. In IEA-DESC, pixel diffusion, DNA encoding, DNA-base permutation and DNA decoding are ...performed successively to generate cipher-images from the plain-images. Some security analyses and simulation results are given to prove that it can withstand various common attacks. However, in this paper, it is found that IEA-DESC has some inherent security defects as follows: (1) the pixel diffusion is invalid for attackers from the perspective of cryptanalysis; (2) the combination of DNA encoding and DNA decoding is equivalent to bitwise complement; (3) the DNA-base permutation is actually a fixed position shuffling operation for quaternary elements, which has been proved to be insecure. In summary, IEA-DESC is essentially a combination of a fixed DNA-base position permutation and bitwise complement. Therefore, IEA-DESC can be equivalently represented as simplified form, and its security solely depends on the equivalent secret key. So the equivalent secret key of IEA-DESC can be recovered using chosen-plaintext attack and chosen-ciphertext attack, respectively. Theoretical analysis and experimental results show that the two attack methods are both effective and efficient.
A systematic methodology is proposed for a chaotic map-based real-time video encryption and decryption system with advanced Reduced Instruction Set Computer machine (ARM)-embedded hardware ...implementation. According to the anticontrol principle of dynamical systems, first, an 8-D discretetime chaotic map-based system is constructed, which possesses the required property of 1-1 surjection in the integer range 0, N - 1, where N is the number of frame pixels, suitable for position scrambling of each video frame. Then, an 8-D discretetime hyperchaotic system is designed for encryption-decryption of red, green, and blue (RGB) tricolor pixel values. Using the ARM-embedded platform super4412 model with Cortex-A9 processor, together with the standard QT cross-platform, an integrated chaotic map-based real-time secure video communication system is designed, implemented, and evaluated. In addition, the security performance of the designed system is tested using criteria from the National Institute of Standards and Technology statistical test suite. The main feature of this method is that, both scrambling-antiscrambling of RGB tricolor pixel positions and encryption-decryption of pixel values are realized simultaneously for enhancing the security. As is well known, compared with numerical simulations, hardware implementation for such a secure video communication system is very difficult to achieve, but we successfully implemented and tested in a real-world network environment. Both theoretical analysis and experimental results validate the feasibility and real-time performance of the new secure video communication system.
This paper aims at developing a systematic methodology for constructing continuous-time autonomous hyperchaotic systems with multiple positive Lyapunov exponents. To overcome the essential difficulty ...in balancing between local instability and global convergence, this paper initiates a new methodology for designing a dissipative hyperchaotic system with a desired number of positive Lyapunov exponents. A general design principle and the corresponding implementation steps are then developed. Three representative examples are shown to validate the proposed principle and implementation scheme. Moreover, a hyperchaotic circuit is constructed to verify a 6-dimensional hyperchaotic system with four positive Lyapunov exponents. Comparing with the traditional trial-and-error approach, the proposed method can design various hyperchaotic systems with any desired number of positive Lyapunov exponents in a systematic way.
Due to the equivalent keys revealed by a chosen-plaintext attack or a chosen-ciphertext attack, most of the existing chaotic image encryption schemes are demonstrated to be insecure. In order to ...improve security performance, some scholars have recently proposed the plaintext-related chaotic image encryption scheme. Although the equivalent effect of a one-time pad is achieved, an additional secure channel is required to transmit the hash values or other parameters related to the plaintext before the ciphertext can be decrypted at the receiving end. Its main drawback is that an absolutely secure channel is needed to transmit the information related to the plaintext, which is not feasible in practical applications. To further solve this problem, this paper proposes a chaotic image encryption scheme based on global dynamic selection of a multi-parallel structure. First, a chaotic sequence is employed to dynamically select DNA encoding rules. Secondly, the permutation with a multi-parallel structure is performed on the DNA-encoded matrix, and the DNA decoding rules are dynamically selected according to another chaotic sequence. Finally, the diffusion rules obtained by the ciphertext feedback mechanism are introduced to determine the dynamic diffusion. Compared with the existing local dynamic encryption schemes, the main advantage of this scheme is that it can realize global dynamic selection, so as to ensure that there is no equivalent key, and it can resist the chosen-ciphertext attack or chosen-plaintext attack and does not need an additional secure channel to transmit parameters related to plaintext, which is practical. A theoretical analysis and numerical experiments demonstrate the feasibility of the method.
This paper introduces a novel fourth-order double-torus chaotic circuit. Based on this basic circuit, a systematic theoretical design approach is proposed for generating 1-Dn torus, 2-D n times ...m-torus, 3-D n times m times I torus, and 4-D n times m times l times p torus chaotic attractors. This is the first autonomous circuit reported in the literature for generating multidirectional multi-torus (MDMT) chaotic attractors. The dynamical behaviors of these MDMT chaotic systems are further investigated, including equilibrium points, bifurcations, Lyapunov exponents, and Poincare maps. Theoretical analysis shows that the MDMT chaotic attractors can be generated by switching and displacing a basic linear circuit. Finally, a block circuit diagram is designed for hardware implementation of the MDMT chaotic attractors. This is also the first time in the literature to experimentally verify a maximal 1-D 20-torus, a maximal 2-D 5 times 5 torus, and a maximal 4-D 5 times 5 times 3 times 3 torus chaotic attractors.
More than 95% patients with acute promyelocytic leukemia (APL) carry the PML-RARα fusion oncoprotein. Arsenic trioxide (ATO) is an efficacious therapeutic agent for APL, and the mechanism involves ...the binding with PML and degradation of PML-RARα protein. Pyrrolidine dithiocarbamate (PDTC) demonstrates the function of facilitating the cytotoxic effect of ATO.
To investigate whether PDTC is potential to enhance the cytotoxic effect of ATO to APL cells by acting on PML-RARα oncoproteins.
Inhibitory effects of drugs on cell viability were examined by CCK-8 test, and apoptosis was evaluated by flow cytometry. Western blotting and immunofluorescence assays were used to explore the mechanism.
PDTC improved the effect of ATO on inhibiting proliferation of NB4 cells in vitro. Further, PDTC-ATO promoted apoptosis and cell cycle arrest in NB4 cells. The expression of caspase- 3 and Bcl-2 was reduced in PDTC-ATO-treated NB4 cells, while cleaved caspase-3 and Bax was up-regulated. Furthermore, less PML-RARα expression were found in PDTC-ATO-treated NB4 cells than that in NB4 cells treated with ATO singly. Laser confocal microscopy showed that protein colocalization of PML and RARα was disrupted more significantly by PDTC-ATO treatment than that with ATO monotherapy.
In conclusion, PDTC enhanced the cytotoxic effect of ATO on APL, and the mechanism was, at least in part, related to the promotion of ATO-induced degradation of PML-RARα fusion protein via forming a complex PDTC-ATO.
In this paper, the security analysis of an image chaotic encryption algorithm based on Latin cubes and bit cubes is given. The proposed algorithm adopts a first-scrambling-diffusion- ...second-scrambling three-stage encryption scheme. First, a finite field is constructed using chaotic sequences. Then, the Latin cubes are generated from finite field operation and used for image chaotic encryption. In addition, according to the statistical characteristics of the diffusion image in the diffusion stage, the algorithm also uses different Latin cube combinations to scramble the diffusion image for the second time. However, the generation of Latin cubes in this algorithm is independent of plain image, while, in the diffusion stage, when any one bit in the plain image changes, the corresponding number of bits in the cipher image follows the change with obvious regularity. Thus, the equivalent secret keys can be obtained by chosen plaintext attack. Theoretical analysis and experimental results indicate that only a maximum of 2.5 × w × h 3 + 6 plain images are needed to crack the cipher image with w × h resolution. The size of equivalent keys deciphered by the method proposed in this paper are much smaller than other general methods of cryptanalysis for similar encryption schemes.
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