952 results about "Chaotic systems" patented technology

Disclosed herein is an encryption and communication apparatus and method using a modulated delay time feedback chaotic system. The encryption apparatus of the present invention includes chaotic signal generating means for generating a high-dimensional chaotic signal in response to an original chaotic signal and a predetermined feedback chaotic signal, delay time modulating means for delaying the high-dimensional chaotic signal output from the chaotic signal generating means by a predetermined time and modulating the time-delayed chaotic signal, and feedback means for receiving the chaotic signal output from the chaotic signal generating means and the modulated time-delayed signal output from the delay time modulating means, performing addition and subtraction operations with respect to the received signals, and feeding the operated result back to the chaotic signal generating means. Accordingly, the present invention is advantageous in that it modulates a delay time so as to prevent an information signal contained in a chaotic signal from being attacked from the outside, so that it is impossible to detect an exact delay time contained in a modulated time-delayed chaotic signal and to decrypt the information signal, thus constructing a more robust and reliable encryption system.

A multiple access telecommunication system is provided, which makes use of chaotic signals. Each transmitter has a chaotic system, which has at least one strange attractor in its phase space, and each receiver has chaotic systems, which corresponds to those in the transmitters from which it may receive signals. Each pair of users is assigned a set of periodic unstable orbits from a strange attractor, which that pair of users may use for signalling. At the transmitter side, a multiplexer receives data from plurality of users. These data are multiplexed in time, to produce an asynchronous data stream. The data stream is then mapped to a sequence of chaotic signals, in accordance with the set of trajectories for each transmitter and receiver pair.

The invention relates to a color image encryption method based on a chaos sequence and a hyper-chaos system. The color image encryption method mainly comprises the following steps: an original color image is subjected to bit level united scrambling to obtain a scrambled image; the scrambled image is decomposed into three primary color components, that is R, G and B, and the hyper-chaos system is used for generating an encryption matrix which is used for encrypting the scrambled image; all pixel values of the three primary color components of the scrambled image are changed by utilizing the encryption matrix in combination with plaintext information and information of the three primary color components, united diffusion is conducted to obtain the three primary color components of the image after the united diffusion, and therefore a final encrypted image is obtained. By means of the color image encryption method, a secret key space is greatly enlarged, the safety, the encryption effect and the sensitivity of a secret key are higher, the anti-attack ability is stronger, and hardware implementation is easier.

A post-quantum physical-layer encryption/decryption system based on chaotic Baseband Modulation Hopping (BMH). The baseband constellation, mapping, power level, and phase will vary symbol-by-symbol according to assigned random sequences. Pre-shared secret keys are used as the chaotic system parameters, initialization, and quantization parameters to generate the BMH codes. The BMH physical-layer encryption/decryption system can be combined with digital-domain based encryption algorithms such as AES, code-based post-quantum cryptography, and other physical-layer secure communication techniques such as Frequency Hopping (FH) and Direct Sequence Spread Spectrum (DSSS). It can also be combined with Quantum Key Distribution (QKD) to provide mutual authenticated key distribution. This invention can be applied to all kinds of communication systems including wireless (radio frequency, optical, quantum channel, sonar) and wire (optical fiber, power-line, telephone line, wire quantum channel, etc.), single carrier and multi-carrier, OFDM, MIMO channels.

The invention discloses a method for realizing the construction of a fractional-order three-system automatic-switchover chaotic system and an analog circuit. The method comprises the following steps: three chaoses and sub-chaoses form an automatic-switchover fractional-order system; the automatic-switchover fractional-order chaotic system is realized by the analog circuit; operational amplifiers U1, U2 and U3 adopt LF346; multiplying units U4 and U5 adopt AD633JN; a voltage comparator U6 adopts LM339; an analog switch U7 adopts CD4052; the operational amplifier U1is connected with the voltage comparator U6, the analog switch U7, the multiplying unit U4 and the operational amplifier U2, the operational amplifier U2 is connected with the voltage comparator U6 and the analog switch U7; the operational amplifier U3 is connected with the operational amplifier U2 and the multiplying unit U4; and the analog switch U7 is connected with the multiplying unit U5; and the multiplying unit U5 is connected with the operational amplifier U3. In the method, the analog circuit is utilized to realize the fractional-order chaotic system in which three subsystems are switched automatically, and the fractional-order three-system automatic-switchover chaotic system is more complicated and has stronger randomness as compared with an automatic-switchover chaotic system composed of two chaotic subsystems and a non-switched fractional-order chaotic system. Therefore, the fractional-order three-system automatic-switchover chaotic system can be a new choice of the signal source of secret communication and has a better application prospect in the secret communication.

A system and method for encoding zero and one bits for transmission, including generating a first signal from a non-linear chaotic system to represent the one bit, with the signal's embedded vectors being within the non-linear system's attractor set, and generating a second signal from the non-linear system to represent the zero bit, with the signal's embedded vectors being outside the non-linear system's attractor set. The second signal encoding the zero bit can be generated by adding together two chaotic signals arising from the non-linear system initialized with different initial conditions, and weighting the second signal to have approximately the same energy as the first signal. One suitable chaotic systems is a Lorenz system. Systems and methods for decoding a transmitted stream of signals compare a detection statistic of the received stream of signals to a threshold value that depends on the chaotic system.

The invention discloses a multi-frequency weak signal detection method for detecting the failure of a rotor in the early stage. A related method is adopted to conduct prophase noise removal, and a chaotic oscillator array scanning method is adopted to realize simultaneous detection of a plurality of frequency weak signals represented by the same failure, that is, signals with noise are denoised through related calculation, a related function is sent to the chaotic oscillator array and serves as a part of chaotic system periodic driving force, and the weak periodic signal of a signal to be detected can be detected through the change of chaotic system phase locus. The method improves the signal-to-noise ratio of the signal to be detected, and completes the detection of multi-feature weak signal through identifying the state of Duffing oscillator, namely the change of phase locus pattern. Therefore, the method has the advantages of simplicity, intuition, definite physical significance and high detection signal-to-noise ratio. Furthermore, the method is capable of completing the weak signal detection of a plurality of known frequencies and easy for engineering realization, thereby having greater development potential.

The invention discloses an integer-order and fractional-order multifunctional chaotic experiment instrument, which can be used for realizing experiment of a three-dimensional or four-dimensional integer-order or fractional-order chaotic system and can output a time-sequence diagram or a phase diagram by a dual-trace oscilloscope. The integer-order and fractional-order multifunctional chaotic experiment instrument comprises a shell and an internal circuit board, wherein the internal circuit board is arranged in the shell; the internal circuit board is provided with a power circuit, an I-part circuit and an II-part circuit; the I-part circuit and the II-part circuit are used for generating chaotic signals and are the same in circuit structure; each part consists of four channels; each channel comprises a signal input circuit, an adder circuit, an integral circuit and a chaotic signal output circuit; each adder circuit is respectively connected with the corresponding signal input circuit and the corresponding integral circuit; and the output end of each integral circuit is connected with the corresponding chaotic signal output circuit. The integer-order and fractional-order multifunctional chaotic experiment instrument disclosed by the invention is simple and reasonable in structure, good in stability, high in reliability and strong in practicability, can be used for teaching in a physical laboratory of the college, can also be used as common scientific and research equipment of the research institutions, and completely meets the research need of the current chaotic phenomenon.

The invention relates to a chaos image encryption method based on dual scrambling and DNA coding, firstly, carrying out bit plane decomposition on a plaintext image and carrying out DNA coding and transformation on the image to turn the image into a three-dimensional DNA matrix; then, scrambling the three-dimensional DNA matrix through the dual scrambling operation, wherein the sequence of the chaotic sequences is scrambled and the DNA sequence is scrambled in a bit level through combining the three-dimensional cat mapping; next, performing diffusion operation on the scrambled three-dimensional DNA matrix, and converting the diffused matrix into a two-dimensional DNA matrix; finally, performing decoding operation on the two-dimensional DNA matrix to obtain a ciphertext image. According tothe invention, the SHA256 hash function of the plaintext image is used to calculate the initial value of the chaotic system, and the parameters of three-dimensional cat mapping are also related to theplaintext image, which enhances the ability of the algorithm to resist the selection of plaintext attack. Experimental results and safety analysis show that the encryption scheme can resist various known attacks, and can effectively protect the security of images and also can improve the security level.

The invention belongs to the technical field of information security, and particularly relates to a color image encryption method based on cellular neural network hyperchaos and a DNA sequence. The method provided by the invention comprises the steps of separating red, green and blue three primary color components of a color plaintext image; updating and generating parameters and initial values of a six-order cellular neural network hyperchaotic system and a Logistic-Sine mapping system through the plaintext image, respectively carrying out iterative operation on the two chaotic systems, and obtaining red, green and blue components of an encrypted image according to a DNA encoding rule and a DNA decoding rule; and finally, changing the pixel values of the encrypted image through key stream and a bitwise XOR operation to obtain a final ciphertext image. The decryption is a reverse operation of the encryption process. Compared with the existing image encryption method, the color image encryption method provided by the invention has the advantages of high security, good encryption effect, strong robustness, no information loss and the like, and thus being capable of being widely used in military, remote sensing, remote medical treatment, commerce and other fields.

The invention discloses a novel digital image encryption method belonging to the field of DNA calculation and image encryption, and provides a digital image encryption method based on a DNA sequence and multi-chaotic mapping. The traditional encryption algorithm based on chaos has the defects that a key space is small, a chaos system is easy to analyze and forecast, and the like; and almost of the current encryption systems based on DNA need complex biological operation and are hard to realize. In order to overcome the defects, the invention provides the digital image encryption method based on a DNA sequence and multi-chaotic mapping, comprising the following steps of: firstly, scrambling the positions of pixels of images by utilizing a two-dimension chaotic sequence generated by Cubic mapping and Haar wavelet functions, and then disrobing the pixel values of the images under the action of a chaotic sequence generated by the DNA sequence and the Logistic mapping. The experimental result shows that the algorithm is easy to realize, has better encryption effect on images, large key space and high sensitivity to keys and can effectively resist exhaustive attack and statistical attack.

The invention relates to a color image encryption method based on an SHA-384 function, a spatiotemporal chaotic system, a quantum chaotic system and a neural network. The method includes the steps that an original color image I0 is calculated through the SHA-384 function, a Hash value is obtained as a secret key, the Hash value, a CML and one-dimension Logistic chaotic mapping are utilized for generating a chaos sequence, bit-level line-column scrambling is carried out on high four-digit images of components of three primary colors of the I0 through the chaos sequence, and a scrambled image I1 is obtained; the Logistic quantum chaotic system is utilized for generating a chaos sequence for encrypting the scrambled image, and is combined with the neural network to carry out parallel diffusion processing on all pixel values of components of three primary colors of the I1, and a final encrypted image I2 is obtained. By the method, the space of the secret key is greatly enlarged, the safety, encryption effect and secret key sensibility are higher, the attack resistance capacity is higher, the scrambling process and the encryption time are shorter, and hardware implementation is easier.

The invention discloses an image fusion encryption algorithm based on DNA sequences and multiple chaotic mappings, belonging to the field of DNA computation and image encryption. The traditional chaos-based encryption algorithm has the defects that the key space is small, the chaotic system is easy to be analyzed and predicted, and the like, and the existing image fusion based encryption method features difficult control of fusion parameters and low safety. To overcome the above defects, the invention first utilizes the two-dimensional chaotic sequence based scrambled coded original image and the template image which are generated by the Cubic mapping and the wavelet function to obtain two DNA sequence matrices, then carries out addition operation on the two scrambled DNA sequence matrices and finally utilizes the chaotic sequence generated by Logistic mapping and the DNA sequence matrices obtained by addition operation to interact to obtain the encrypted image. The experimental results show that the algorithm can effectively encrypt the digital images and has higher safety.

The present invention relates to a DNA dynamic coding based colored image encryption method, comprising: obtaining a key through a colored plain-text image; by the key, calculating an initial value and a parameter of a chaotic system used in scrambling and diffusion processes; substituting the initial value and the parameter to the chaotic system for iteration to obtain W1 and W2, obtaining a scrambling matrix K from W1, obtaining an integer matrix Y and an index matrix Ind from W2, and performing DNA coding on Y according to the index matrix Ind; and performing scrambling on the plain-text image row by row by using the matrix K, then performing coding and diffusion until all rows finish DNA coding, and finally performing decoding and recomposing on a DNA matrix, to obtain a final colored ciphertext image. According to the method, a function SHA256 is used to generate the key, so that the key space is expanded; the generation of the key depends on a plain-text, so that plain-text attack can be effectively resisted; chaotic characteristics are combined with DNA dynamic coding, so that the security is further improved; and meanwhile, scrambling and diffusion operations are performed according to the row of images, so that parallel computing is facilitated and the efficiency is improved.

The invention discloses an encryption and decryption method for numeric type data. The method comprises the following steps that the numeric type data is converted into character strings; each character is sequentially converted into 4 bits according to the correspondence relationship between the numeric characters and the binary system, and a bit stream is formed; the number of 0 and 1 in the bit stream is counted, and an encryption secret key is obtained through calculation; the encryption secret key is utilized, a chaotic sequence with the pseudo-random property is generated by a chaotic system, in addition, chaotic signals are taken from the chaotic sequence and are sequenced in an ascending sequence, and the bit stream is scrambled according to the positions in accordance with the scrambling rule; the corresponding relationship between the four-digit binary coding mode and the visible ciphertext characters is utilized for converting the scrambled bit stream into the visible ciphertext character strings, and the ciphertext can be decrypted and recovered into the original data type data through adopting the similar method. According to the method provided by the invention, the corresponding table customization is adopted, the numeric type data is subjected to binary scrambling chaotic encryption processing, the safety and the feasibility of the data encryption are ensured, and in addition, the encryption efficiency is also greatly improved.

The invention provides an image encryption method based on a two-dimensional compression perception and chaotic system. A wavelet sparse basis is used to carry out sparse representation of an image to generate a sparse matrix, then a random sequence generated by a two-dimensional sine-logistic chaotic system iteration is used to generate a measurement matrix, the measurement matrix is used to carry out compression measurement of the sparse matrix, and a preliminary compression encrypted image which is an intermediate result is obtained. In order to enhance the attack resistance ability of the system, the chaotic system is used again to generate a chaotic series to carry out pixel scrambling and cyclic shift operations on the intermediate result, and a final encryption map is obtained. According to the method, the two-dimensional sine-logistic chaotic system is used, the sequence randomness is increased, and the scrambling effect of the image is enhanced. The key space is expanded, the safety of an encryption system is enhanced, an excessive ciphertext data quantity is avoided, and a good encryption effect is achieved.

The invention discloses a method for automatically switching a fractional-order chaotic system by four systems based on a Lu-type system and an analog circuit. The analog circuit comprises an operational amplifier U1, an operational amplifier U2, an operational amplifier U3, an operational amplifier U5, an operational amplifier U8, a multiplier U4, a multiplier U9, a multiplier U10, a voltage comparator U7 and an analog switch U6. By the analog circuit, the fractional-order chaotic system can be automatically switched by four Lu-type subsystems. The analog circuit is more complex than automatically switched chaotic systems formed by two or three sub-chaotic systems and fractional-order chaotic systems that are not switched, has higher randomness, can be a new choice for a signal source for confidential communication, and has brighter application prospect in confidential communication.

An active vibration control system including a sensor responsive to a source of vibration and which provides an output signal representative of the vibrations; at least one actuator positioned to impart canceling vibrations to the source of vibrations based on an input signal; a correction subsystem responsive to the actuator for estimating the sensor output in the absence of the canceling vibrations and which outputs a corrected output signal representative only of the vibrations emanating from the source; and a state space predictor responsive to the corrected output signal for determining the input signal to the actuator based on variations in the corrected output signal to better control vibrations especially in chaotic systems.

The invention discloses a five-dimensional chaotic system and a chaotic signal generator based on the five-dimensional chaotic system, and relates to the information encryption field. The five-dimensional chaotic system provided by the invention is small in quantity of occupied digit circuit multiplying units, easy to implemented and large in chaotic system parameter range, so that complex chaotic signals are obtained, and the information encryption safety is improved. The five-dimensional chaotic system is used for inputting five chaotic signals and has typical chaotic attractors. An FPGA (Field Programmable Gate Array) in the chaotic signal generator is used for generating a five-dimensional chaotic system circuit, and the five chaotic signal output ends are respectively connected with the digital signal input ends of first, second, third, fourth and fifth digital analog converters. One end of a dial switch is connected with a power supply while the other end of the dial switch is respectively connected with the power supply ends of the five digital analog converters. The signals output by the five digital analog converters are voltage signals. The chaotic signal generator can provide a five-dimensional chaotic signal source which has various association of variation, is used for information encryption and has good chaotic characteristics.

The invention discloses a memristor hyperchaos system and circuit with abundant dynamic behaviors. The new fifth-order memristor hyperchaos system is provided and has the abundant chaos dynamic behaviors and phase track graphs at different angles, and the different chaos behaviors such as grids and scrolls can be seen. A basic step for generating a complex dynamic chaos system through a memristor in future is made.

The invention relates to an image encryption algorithm based on a chaotic system, used for solving security problems that the image encryption algorithm is small in key space and poor in capacity of resisting to plaintext attacks. The algorithm comprises four modules such as a hyperchaos sequence generator, a forward diffusion module, a scrambling module and a reverse diffusion module. Firstly thehyperchaos Chen system is used for generating four chaotic pseudorandom sequences, a chaotic sequence and a plaintext image are used for performing forward diffusion operation to acquire a matrix A,then computation is performed in combination with the pseudorandom sequences and information related to the plaintext image to acquire a scrambled coordinate, the coordinate scrambling is performed onthe matrix A to acquire a matrix B, and at last the chaotic pseudorandom sequences and the matrix B are used for performing reverse diffusion operation to acquire a ciphertext image C. An experimentsimulation result expresses that the algorithm can improve the defect that the image encryption algorithm is small in key space, effectively resist to statistical attacks, differential attacks, and chosen-plaintext attacks, and achieve good encryption effect.

The invention discloses a image counterfeit deterrence method based on the chaotic feature, comprising: first, by the chaotic mapping system, using the information needed keep secret and counterfeit deterrence to generate the chaotic sequence which is used to encode the information, then, printing the encoded information to the two-dimension bar code image according to the PDF417 bar code; collecting the two-dimension bar code image by the scanner, and operating the preprocessing of image segmentation, filtration, geometric correction and stratified on collected image, then decoding the bar code according to the decoding rule of national standard PDF417 bar code to attain the chaotic encoded information carried by bar code image. The invention fully utilizes the features of chaotic system and two-dimension bar code technique which are combined for image counterfeit deterrence. The invention has the characters as strong secret-keeping property and large information carried, while it can recognize automatically.

The invention relates to a different-dimensional switchable chaotic system design method and a circuit; a four-dimensional hyper-chaos system is constructed by adding variables and feeding back control items based on a three-dimensional generalized Lorenz system family; and a switchable different-dimensional chaotic circuit is designed through a plurality of switch controllers in Multisim software. An analog circuit constructed by the invention is convenient to use and easy to realize by hardware, and has relatively lower cost; the designed switchable circuit not only can flexibly realize the switching between a three-dimensional chaotic system and the four-dimensional hyper-chaos system, but also can return to realize the switch among three chaotic systems in the same dimension; and the systems can serve as practical chaotic modulation and chaotic encryption signals, and can be widely applied to the field of information security cryptography with higher requirements on confidentiality and reliability.