50 results about "Bitmessage" patented technology

A digital watermarking technique is disclosed, in which image data are converted to frequency components through discrete wavelet transform and quantized into a set of quantized coefficients, which are then divided into a plurality of blocks. A digital watermark is embedded in the quantized coefficients by performing ON / OFF adjustment of bit information, such that the relation between natural number T and the bit information defined by N (N is an even number) significant bits Qnm (x, y) of the m-th bit plane of the n-th block satisfies the ON state represented by equation (1), or the OFF state represented by equation (2), depending on whether the hash value of the n-th block is odd or even. Then the quantized coefficients are encoded to produce a code stream.

The invention discloses an improved multi-user DCSK chaotic communication system, and belongs to the technical field of communication. A traditional differential chaos shift keying (DCSK) modulation technology is improved so as to achieve the purpose of improving the bit error rate performance. An improved chaotic signal generator is used at a sending end to generate a group of orthogonal chaoticsequences xi and k, so that each path of information signal can transmit two bits and is expanded into multiple users, and each frame of signal can transmit 2N information bits. At a receiving end, received signals ri and k are converted through an editor used by the sending end, then corresponding correlation operation is carried out, and after threshold judgment is carried out, corresponding bitinformation can be recovered, wherein the threshold judgment criterion is as follows: if the output result of the related demodulator is greater than or equal to 0, the sent information signal is judged to be '+1'; otherwise, it is judged that the sent information signal is'-1'. Compared with a DCSK system, an OMU-DCSK system and an NISI-MU-CDSK system, the system provided by the invention has better error code performance. Therefore, the improved multi-user DCSK chaotic communication system has important application value in the field of communication.

In a wireless communication system, a transmission device inputs, in some of N input bit positions of a polar code having the size N, input bits including D-bit information and X-bit user equipment (UE) ID according to a predetermined bit allocation sequence. The transmission device encodes the input bits by using the polar code. The transmission device transmits an encoded output sequence.

A system and method for migrating from the legacy SMTP protocol to an alternative email protocol, such as Bitmessage protocol, for sending email messages comprising a publicly accessible directory which associates the alternative email protocol addresses with an SMTP addresses of a particular recipient, and a server that accepts an outgoing message sent by SMTP protocol and routes the outgoing message via the alternative email protocol if recipient's SMTP address and a corresponding alternative email protocol address is found in the directory, and routes the message by SMTP protocol if no corresponding alternative email protocol address is found in the directory.

The invention belongs to the technical field of chaos secrecy, and discloses a robust chaos keying secure communication system and communication method, a terminal and a storage medium. At a sending end, a double-delay feedback chaos keying system is designed, one fixed delay feedback is used for guaranteeing the chaos characteristic of the system, the other controllable delay feedback is used for bearing 0 and 1 bit information, and uses a 0 or 1 state for controlling on / off state of delay feedback; the sending end respectively trains a neural network by using a chaotic signal output by a system and a delay signal thereof to establish two relation models in an on / off state of a delay keying modulation module. At a receiving end, segmented verification is performed on the mapping relation between the modulated chaotic signal and the delay signal by using the two models, and decryption is performed on the premise of not recovering the chaotic carrier of the sending end. The secure communication system based on robust chaos keying comprises a nonlinear transformation module, a delay keying modulation module, a plaintext electric signal module, a relation model establishment module, a channel, a first delay prediction module, a second delay prediction module, an analog-to-digital conversion module, a clock control module, a segmentation similarity comparison module and a demodulation module. The method can effectively resist the return mapping attack for chaos keying, and provides possibility for secure transmission under severe communication conditions.

The invention provides a method and a device for preventing false detection of a PDCCH and a readable access medium. The method comprises the following steps: performing hard decision on soft bit data output after performing rate de-matching on blind detection data; decoding and cyclic redundancy check are carried out on the soft bit data, and the data passing through the cyclic redundancy check are coded; comparing the coded data with a hard decision result, and calculating the ratio of different bits between the coded data and the hard decision result relative to soft bit data; when it is judged that the ratio is larger than or equal to a preset first threshold value and the blind detection data meet a first condition, or when the ratio is smaller than the preset first threshold value and the blind detection data meet a second condition, different bit numbers between bit information of the blind detection data and bit information of the PDCCH successfully detected last time in historical information are determined; determining a difference representation value according to different bit numbers; and determining that PDCCH false detection is generated when judging that the difference characterization value is greater than a second threshold value. According to the invention, the situation of false detection of the PDCCH can be prevented.

The existed coding / decoding method with low density odd-even check code cannot reduce the small circulation existing in the checking matrix. The said small circulation depresses the coding feature. The technical scheme of the invention finds out the weak bit in the related signal original bit group in the given check matrix. When the coding end groups the signal source bits to be set, the scheme obtains corresponding code words after inserting appointing bit info promised by both sending and receiving ends into weak bit of each group. According to the appointed bit info, the decode end initializes the probability info related to the weak bit node into a value close to infinity. Thus the scheme raises the accuracy of probability info transferred between the bit node and the checking node during the iterative progress. The invention also corrects the error info of adjacent nodes. These raises decoding feature and obtains an obvious coding gain.

A communication network authenticates the source of messages transmitted on a flat bus to determine the presence of spoofing events. A programmable intrusion detection device is connected to the bus at a fixed location and compiles templates for various tri-bit signal pulses that form the data transmitted as messages between network nodes. Each tri-bit template compares unique signal characteristics inherent in the signal waveform received by the device from each node, the unique characteristics being directly attributable to the physical topology of the network. In use, the device uses the templates to calculate an inferred source identifier for each message. The inferred source identifier is then compared against the declared source identifier, which is embedded in message metadata, to authenticate the message source. Any lack of reconciliation between the inferred and declared source identifiers causes the device to mark the message as spoofed and initiate a designated response.

The invention discloses a sequence cipher encryption system key updating method based on a hash function, and belongs to the field of communication information security. The method comprises the following steps: initializing a key K0, and synchronizing the states of m sequence generators of a transmitting end and a receiving end and an integral shift register; performing encryption and decryption operation on the key Ki; inputting, by the m sequence generator, a 1-bit signal, and performing shift by the whole shift register; compressing the key Ki by adopting a hash function to generate a new key K; and when a key updating condition is triggered, enabling the sending end and the receiving end to perform key updating, and taking K as a new key. According to the invention, the problem of safe and rapid key transmission during key updating and encryption and decryption interruption caused by initialization of the key stream generator are avoided, and seamless connection of a new key stream and an old key stream is realized.

The invention discloses a modified belief propagation method based on set destruction, which includes: step 1, receiving the code word transmitted by the additive white Gaussian noise AWGN channel through the receiving end and undergoing binary phase shift keying BPSK modulation; step 2, setting the iteration The number k is 0, calculate v n and z n , set v mn and umn are both equal to zero; step 3, update the bit information v of the bit node n at the kth iteration mn ; Step 4, update the check information u sent by bit node n to check node m mn ; Step 5, update the iterative hard decision value z of each bit node n n , and modify the variable information of the bit node where information oscillation occurs; step 6, judge whether the preset iteration stop condition is satisfied, if so, terminate the decoding process and output the hard decision vector z of the kth iteration of the bit node n k , otherwise return to step 3.

Provided is a method of transmitting security information of a single-bit analog-to-digital converter (ADC) wiretap channel. In the method of transmitting the security information of the single-bit ADC channel, a transmitting terminal adds additive noise to a transmission signal and transmits the transmission signal, and a receiving terminal and a wiretap terminal which each include a single-bit ADC receive the transmission signal, wherein received information is processed so as not to be determined by the wiretap terminal. When intensity of additive noise of the receiving terminal is less than that of additive noise of the wiretap terminal, a binary phase-shift keying (BPSK) distribution is used, and when the intensity of the additive noise of the receiving terminal is greater than that of the additive noise of the wiretap terminal, a codebook is designed using an asymmetric BPSK distribution in which both of two message points have a positive value.

The invention belongs to the technical field of chaos security, and discloses a robust chaos keying security communication system, a communication method, a terminal and a storage medium. At the sending end, a double delay feedback chaos keying system is designed, and a fixed delay feedback is used for To ensure the chaotic characteristics of the system, another channel of controllable delay feedback is used to carry 0 and 1 bit information, and the 0 or 1 state is used to control the closure and opening of the delay feedback; when the transmitter is in the open / close state of the delay keying modulation module, The chaotic signal output by the system and its delayed signal are used to train the neural network to establish two relationship models; at the receiving end, the two models are used to verify the mapping relationship between the modulated chaotic signal and the delayed signal segmentally. Decryption is performed under the premise of chaotic carrier at the terminal. The invention can effectively resist the return mapping attack on chaotic keying, and provides the possibility for safe transmission under severe communication conditions.

The present disclosure provides a method, device and readable access medium for preventing false detection of PDCCH, including: performing hard judgment on the soft bit data output after performing rate matching on the blind detection data; decoding and looping the soft bit data Redundancy check, encode the data after passing the cyclic redundancy check; compare the encoded data with the result of the hard judgment, and calculate the ratio of the different bits between the two to the soft bit data; judge When the ratio is greater than or equal to a predetermined first threshold and the blind detection data meets the first condition, or, when the ratio is less than the predetermined first threshold and the blind detection data meets the second condition, determine the bit information of the blind detection data The number of bits different from the bit information of the last successfully detected PDCCH in the historical information; determining the difference characteristic value according to the different number of bits; determining that a PDCCH misdetection occurs when the difference characteristic value is greater than the second threshold value. The present disclosure can prevent the occurrence of PDCCH false detection.

The invention relates to a LDPC code sparse check matrix reconstruction method and system. The method includes: randomly extracting bit information once from the entire low density parity check code (LDPC code), and analyzing the bit information randomly extracted once to determine the minimum number of extractions; and randomly extracting the LDPC code based on the minimum number of extractions multiple times of bit information, and determine the suspected sparse check vector according to the multiple times of the bit information; obtain the channel error rate, and determine the minimum error decision threshold based on the signal error rate; determine the minimum error decision threshold according to the minimum error decision threshold Describe whether the suspected sparse check vector is a correct sparse check vector; if so, rebuild a sparse check matrix according to the correct sparse check vector; the sparse check matrix is ​​used to decode the communication information; if not, re-decode the LDPC The code randomly extracts multiple bits of information. The invention can reduce the computational complexity and improve the fault tolerance performance.

The invention discloses a differential chaos shift keying modem and a differential chaos shift keying modulation method based on two-path index modulation, and relates to the technical field of chaoscommunication. A two-path index modulation method is used for transmitting a chaos reference signal and a Hilbert reference signal orthorhombic with each other, and an index mapping rule and an inverted index mapping rule are used for modulating and demodulating the signals. According to the modulation method provided by the invention, delay units are used in a transmitting terminal and a receiving terminal; compared with an existing carrier-index differential chaos shift keying (CI-DCSK) technology, under the premise of occupying a same frequency band, the method synchronously transmits two information signals, so that a bit transmission rate of the system is doubled; in addition, the higher spectrum utilization rate and better data security are achieved, and the method provided by the invention is reduced in bit error rate (BER), and shows better bit error rate performance, and the advantages of the BER performance becomes more significant along with the increasing of a bit signal tonoise ratio.

The invention relates to a selective protection method based on a Viterbi decoder. On the basis of realizing the Viterbi decoder based on FPGA and calculating the bit width of the register, it includes: selectively protecting the Viterbi decoder: SEU tolerance Register bits with a value of 0 adopt triple-mode protection: add two bits of redundant information to all bit positions at the same time, store the same information as the original bit position, and the final result is based on any two bits of the same bit information. Two-mode protection is performed on the bit position of the SEU fault-tolerant register: each bit adds a corresponding bit of redundant information, stores the same information as the original bit position, and then adds a logical AND gate, and the output result of the AND gate is The protected bit position final result.

Aiming at the limitation of the prior art, the invention provides the method for identifying the lost tag of the large RFID system based on the balanced collision binary tree, the data structure of the balanced collision binary tree is proposed and used for the first time in the field, and a binary query tree of which the leaf nodes are highly balanced is constructed for a target RFID system, so that the lost tag of the target RFID system is identified. Compared with a traditional collision tree, the height is obviously reduced, and the time overhead of broadcasting information by the reader-writer is further greatly reduced; the Manchester encoding principle and the CPT tree structure are combined, so that the use of an empty time slot is thoroughly avoided, and whether two tags are lost or not can be synchronously detected from one time slot only by using one-bit information, thereby greatly improving the utilization rate of frames and time slots. On the premise of ensuring the same recognition accuracy, compared with the prior art, the method has the advantages that the progressive overhead is maximally reduced by a multiple factor which is nearly log N, the performance is greatly improved in various parameter environments, and the robustness and the expansibility are good.