163 results about "Artificial noise" patented technology

The invention discloses a resource allocation optimization method for a multi-IRS unmanned aerial vehicle communication-sensing-calculation integrated system, and the method improves the safety rate of the system through employing a multi-IRS-assisted sensing beam and a communication beam, and reducing the signal-to-interference-noise ratio (SINR) of an eavesdropper through artificial noise. The invention provides a hybrid SAC intelligent optimization algorithm based on deep reinforcement learning. According to the algorithm, discrete actions such as deployment points, task unloading ratios, artificial noise power and the like of D-UAV and I-UAV are optimized in a combined mode through a discrete SAC algorithm, continuous actions such as IRS phase shift and the like are optimized through a continuous SAC algorithm, and the aim is to optimize the safety rate of a system. Simulation results show that the intelligent optimization scheme provided by the invention is superior to other comparison schemes under different transmitting powers and different numbers of IRS arrays.

Methods and devices for detecting a defect in a rail of a railway track, include at least two sensors selected from among magneto-acoustic and / or piezoelectric and / or magnetostrictive transducers; each sensor being associated with a timestamping circuit of a GNSS satellite positioning system; a measuring circuit for measuring, by way of the sensors, the acousto-elastic waves propagating in the rail, the wave or signal measurements being timestamped. Some developments describe notably active and passive modes; the use of train crossings; the emission of waves; the determination of the existence and then of the position and finally the characterization of the defect, where applicable; preferred placements for installing the sensors; the use of inter-correlation, passive inverse filter or correlation of coda of correlation methods; the use of mobile robots and / or drones; the use of artificial noise sources.

The invention discloses an optimization method for secure transmission of an active STAR-RIS assisted RSMA communication system. The optimization method mainly comprises the following steps: S1, constructing an active STAR-RIS assisted multi-input single-output RSMA communication system; s2, the base station transmits the information to legal users in the system through the active STAR-RIS; s3, the base station sends the artificial interference noise while sending the useful signal; constructing an optimization equation for maximizing system private information and safety rate based on beam forming, artificial noise, an active STAR-RIS power amplification matrix, an amplitude matrix and a phase shift matrix as optimization parameters; s4, performing proper conversion on a non-convex objective function and constraints by using a WMMSE criterion, and performing decoupling solution on an optimization problem by using an AO algorithm; s5, updating an auxiliary variable introduced by the WMMSE algorithm according to the closed expression; s6, using an SCA algorithm to optimize and update beamforming and artificial noise of the base station, and a power amplification matrix and an amplitude matrix of the active STAR-RIS; and S7, adopting an SCA algorithm and a PDD algorithm to optimize and update the phase shift matrix of the active STAR-RIS. According to the invention, the security of the communication system is obviously improved.

Disclosed in the present invention is a secrecy rate optimization method for a simultaneous wireless information and power transfer system. The method comprises: constructing a simultaneous wireless information and power transfer system, which includes an intelligent reflecting surface apparatus, an access point, a plurality of legitimate users and a plurality of eavesdroppers, wherein the intelligent reflecting surface apparatus is provided with a plurality of reflecting elements, and adding artificial noise to an information signal transmitted by the access point; for the simultaneous wireless information and power transfer system, establishing a secrecy rate optimization problem, and in the secrecy rate optimization problem, taking interference between the users into consideration and describing channel state information of the eavesdroppers; and for the secrecy rate optimization problem, jointly optimizing a power splitting ratio, transmission beamforming, a covariance matrix for the artificial noise, and a phase shift matrix for the intelligent reflecting surface apparatus, wherein the power splitting ratio is used for limiting a legitimate user to splitting a power into an information decoding part and an energy harvesting part. The present invention is more applicable to an actual communication scenario, reduces the eavesdropping rate, and thus increases the overall rate of a system.

A method is provided performed by a network node without a direct communication link with a plurality of UEs to collaboratively train a machine learning, ML, model based on a relay assisted distributed ML with over-the-air computation and data privacy. The method includes receiving (506) further modified local ML model gradients from a relay over wireless channels. A further modified local ML model gradient includes a local ML model gradient modified by a respective UE with a first artificial noise for data privacy which is further modified by the relay with a second artificial noise for data privacy. The method further includes aggregating (508) the further modified local ML model gradients based on an over-the-air computation; constructing (510) an updated ML model; and performing (512) one of (i) transmitting the updated ML model to the relay, or (ii) configure variables and start a next round of the collaborative training.

The invention discloses a semantic camouflage communication method and system, a power grid and electronic equipment, and relates to the technical field of power system safety. According to the method, semantic information extracted from a to-be-sent image by a semantic encoder of the semantic communication system is obtained at a sending end of the semantic communication system, and then a semantic information decoding module used for ensuring that both a legal user and a potential eavesdropper in a deployment environment of the semantic communication system can decode is added to the semantic information, and the legal user decodes to obtain the to-be-sent image, and the potential eavesdropper decodes to obtain the artificial noise of the disguised image, so as to obtain the transmission semantic information, pre-codes the transmission semantic information, and sends the pre-coded transmission semantic information. Therefore, the problems that when semantic communication is adopted to carry out power data transmission, confidentiality is maintained through encryption or a physical layer security system, an eavesdropper is easily aware of protection measures, and data transmission security is not high due to the adoption of more complex attacks are solved.

The invention relates to an electric power communication system optimization technology, in particular to a physical layer security optimization method and equipment for a full-duplex multicarrier power line communication system, and the method combines a full-duplex technology and a time domain artificial noise auxiliary security strategy to construct a multicarrier power line communication system model with a relay; generating a safety rate maximization problem, designing a set of convex approximation method, and performing conversion and simplification of a non-convex optimization problem; designing an iterative solution algorithm, and jointly optimizing the confidential data of the source node, the confidential data of the relay node and the artificial noise power distribution matrix; and optimizing the physical layer safety performance of the full-duplex multi-carrier power line communication system based on the solved power distribution matrix. According to the communication scheme and the solved power distribution vector, the safety performance of the power line communication system is optimized, the limitation of the number of power transmission cables in the power line communication system is avoided, the safety rate maximization of the total transmitting power domain can be realized, and the technical problem that data in an existing multi-hop power line communication system is prone to leakage is solved.

The invention relates to the technical field of wireless communication networks, and discloses a communication optimization method and system for a wireless energy-carrying safety communication system in a far and near mixed field. The method comprises the following specific steps: constructing a wireless energy-carrying safety communication system in a far-near hybrid field, wherein the wireless energy-carrying safety communication system comprises a base station, an energy collection receiver with K near-field single antennas and an information decoding receiver with M far-field single antennas; constructing a mixed field channel model; constructing a signal model comprising the information signal and the digital beam forming matrix thereof, and the artificial noise and the digital beam forming matrix thereof; based on the signal model and the mixed field channel model, a maximization problem objective function of the minimum safety rate weighted sum of the information decoding receiver is formulated; and solving a maximization problem to obtain an optimal communication scheme. The method solves the problem that vector optimization of beam forming is lacked in the prior art, and has the characteristic that the information transmission security of the system can be improved.

The invention discloses a spectrum resource allocation method, which comprises the following steps of: deploying a plurality of pairs of information transceivers, a passive backscatter label group and an eavesdropping user in a backscatter communication system, each passive backscattering label is equipped with an energy collection and conversion module and an information reflection module; constructing a resource allocation model meeting a reflection signal and rate maximization of secure communication; constructing a directed hypergraph based on a backscattering system and coloring the directed hypergraph; in order to solve the non-convexity problem of a resource optimization model, an auxiliary variable is introduced to remodel a resource allocation model, and eavesdropping threats are reduced from the physical level. The method provided by the invention can maximize the sum rate of the reflected signals in the system on the premise of ensuring the secure communication of each sub-channel, effectively reduces the interference among the reflected signals by dividing spectrum resources and introducing artificial noise, restrains the influence of eavesdropping users on the security of the system, and meets the requirements of the users on the quality of service.

The invention discloses a wireless audio star flash transmission noise management method and system suitable for a conference system, and the method comprises the steps: obtaining to-be-transmitted audio information, coding the to-be-transmitted audio, carrying out the preliminary separation of the to-be-transmitted audio based on a non-negative matrix factorization algorithm, and obtaining the separated audio information; performing audio classification according to the separated audio information, and classifying to-be-transmitted audios into different audio types to obtain audio classification information; acquiring environment sound audio information according to the audio classification information, forming an environment sound audio sequence, and performing noise reduction management; human voice audio analysis is carried out, the human voice audio is divided into background human voice audio and target human voice audio, noise reduction is carried out on the background human voice audio, and anomaly detection is carried out on the target human voice audio; and carrying out comfort evaluation on the target human voice audio, judging whether human noise exists or not, carrying out audio prediction, and generating noise reduction regulation and control parameters. And the audio transmission noise management quality of the conference scene and the comfort of participants are improved.

Methods and devices are provided for analyzing a tubular structure including at least two electromagnetic-acoustic transducers (EMAT) and, called sensors, attachable or attached in, on or in the vicinity of the tubular structure; and computation and / or memory resources, that are accessed locally and / or remotely and that are configured to determine, for the pair of sensors, a function representing the impulse response of the tubular structure on the basis of the diffuse acousto-elastic noise present in the structure. Developments describe the use of rings supporting the sensors; translation and / or rotation movements; permanent or temporary installations; hinged rings; various computation modes, e.g., intercorrelation, a passive inverse filter, or correlation of the coda of the correlation; the use of artificial noise sources, imaging (e.g., tomography) for determining the existence of one or more defects in the structure. Software aspects are described.

The invention discloses a secure communication method based on artificial noise in an unmanned aerial vehicle NOMA network. The communication process has two time slots. In a first time slot, a base station adopts an NOMA mechanism to send a signal to an unmanned aerial vehicle, meanwhile, the unmanned aerial vehicle selects one antenna to send an artificial noise signal to interfere with an untrusted remote user, the remaining antennas receive the signal, and a near user also sends the artificial noise signal; in a second time slot, the unmanned aerial vehicle adds the artificial noise signal and the near user signal of the first time slot by means of exclusive OR, then superposes the obtained signal and the far user signal by means of an NOMA mechanism, and finally reselects one antenna to send the superposed signal; then the NOMA user obtains a corresponding signal to interference plus noise ratio or a signal to noise ratio according to the received signal, and calculates a system outage probability and an eavesdropping probability; the method can effectively weaken the eavesdropping capability of the untrusted user, basically does not affect the untrusted user to receive the own message, and helps to solve the problem of potential safety hazards in an actual unmanned aerial vehicle cooperative NOMA network communication scene.

The invention discloses a finite block length secure transmission method and system based on communication perception integration, and relates to the technical field of communication. Comprising the following steps: S1, constructing a system model, determining an optimization problem, analyzing a safe transmission rate capable of reaching a limited block length, and constructing a safe rate maximization problem; s2, designing an optimization scheme: decomposing the non-convex optimization problem in the S1 into three sub-problems, namely uplink transmission power distribution of IoE equipment, sensing signal design and joint sensing and communication receiving beam forming optimization, converting each sub-problem into a solvable convex optimization problem, and respectively solving the solvable convex optimization problem, and obtaining the solution of the original problem through an alternate iteration method until the algorithm converges or reaches the maximum iteration times. According to the method, a potential threat source is identified more accurately by utilizing a sensing data auxiliary system, and the technologies of beam forming, artificial noise and the like are utilized, so that the secure transmission between legal users is ensured, the quality of a received signal of an eavesdropper is reduced, and the secure fusion of a communication function and a sensing function is realized.

The invention discloses an optimization method of active STAR-RIS auxiliary NOMA (Non-Orthogonal Multiple Access) secure communication transmission. The method comprises the following steps: S1, constructing an active STAR-RIS auxiliary uplink NOMA secure wireless communication system; and S2, the link of the user 1-BS and the link of the user 2-BS are blocked due to obstacles or a long distance, and the legal user transmits information to the base station of the receiving end through STAR-RIS. S3, in order to improve the safety of the system, the base station sends the useful signal and the artificial interference noise at the same time; under the scene that the total emission energy of a base station is limited, an optimization equation which is based on beam forming, artificial noise and IRS phase shift parameters and is used for maximizing the system safety rate sum of optimization parameters is constructed. And performing decoupling optimization solution on active beam forming, artificial noise and IRS phase shift parameters of the base station based on an alternating optimization algorithm. According to the invention, the total safety rate of the system can be obviously improved.

Methods, systems, and devices for wireless communications are described. A wireless device may receive scheduling information that schedules temporally overlapping transmissions by the wireless device of a data signal and an additional signal, where the additional signal includes an artificial noise signal, an energy signal associated with an energy-harvesting device, or both. The wireless device may then align a starting symbol of the additional signal with a starting symbol of the data signal based on the data signal and the additional signal being scheduled to temporally overlap, and may transmit the data signal and the additional signal based on the aligning.

The invention relates to the technical field of wireless communication, and discloses a data encryption transmission method, a decryption method, communication equipment and a storage medium. The method comprises the following steps: encrypting original channel data by using a target security key to obtain ciphertext channel data; performing random beam forming processing on the ciphertext channel data to obtain target channel data with artificial noise; wherein the artificial noise is determined based on a target angle between the base station and the target equipment, and a target security key is stored in the target equipment; sending the target channel data to a target device at the target angle, so that the target device decrypts the target channel data by using the target security key; wherein no artificial noise exists on the target equipment. Therefore, through a dual encryption method, the eavesdropping success rate is remarkably reduced, and the data confidentiality and the anti-attack capability of a wireless link are effectively improved.

A hidden communication method for confronting a full-duplex eavesdropper based on probability transmission in symbiotic radio comprises the following steps: constructing a system model which comprises a main transmitter Alice, a main receiver Bob, an auxiliary transmitter BD and a full-duplex eavesdropper Willie; the main transmitter Alice selectively transmits information according to a link channel state with the main receiver Bob; when the channel gain # imgabs0 # of a legal link is greater than a preset threshold value delta, the information is transmitted; otherwise, the information is not transmitted; the auxiliary transmitter BD secretly sends confidential information to the main receiver Bob through a reflection link by using the transmission behavior of the main transmitter Alice, and the full-duplex eavesdropper Willie works in a full-duplex mode and simultaneously sends artificial noise to interfere legal communication and eavesdrop. The technical problem to be solved by the invention is to provide the hidden communication method for confronting the full-duplex eavesdropper based on probability transmission in the symbiotic radio, the strong eavesdropper is confronted by using the uncertainty of link information, and the detection performance and the concealment performance of the eavesdropper are comprehensively analyzed.

The invention discloses a beam forming method of an RIS-assisted NOMA-ISAC system for preventing internal and external eavesdropping, which ensures that radar sensing requirements are met under the condition of limited energy resources by intelligently optimizing transmitting beams of a base station and a phase shift matrix of an RIS, effectively resists attacks of potential internal and external eavesdroppers, and improves the reliability of the system. Therefore, the security communication performance of legal users of the system is obviously improved. Specifically, according to the method, radar signals of a base station are ingeniously utilized, while a radar target sensing task is executed, the radar signals serve as artificial noise to interfere with potential eavesdroppers, and the dual functions of target sensing and safe communication are achieved. However, the optimization problem of minimizing the legal signal power of the system has non-convex constraint and is difficult to directly solve, so that the original problem is decomposed into three sub-problems, the sub-problems are converted into a convex optimization problem by using a positive semi-definite relaxation technology, and finally alternate optimization solution is performed through a CVX toolbox. According to the strategy, the complexity of the problem is effectively reduced, and the calculation efficiency is improved.

The invention provides a transient electromagnetic data noise suppression method based on a neural network, and the method mainly comprises the steps: constructing a CNN-LSTM neural network based on improved SPPFCMA optimization, generating synthetic training data, and designing a mixed loss function. The network comprises a convolutional layer, a pooling layer, a bidirectional long and short time memory layer and a full connection layer. By improving an SPPFCMA module, a CA attention mechanism is added after convolution layer output, and multi-scale pooling branches are adopted. A method of generating synthetic training data includes simulating a noiseless TEM signal using one-dimensional forward modeling and superimposing artificial noise. The training termination condition is that the mixed loss function value of the verification set does not decrease in continuous five iterations, and the method is used for denoising the actually measured data after preprocessing the actually measured data.

The embodiment of the invention discloses a mobile covert communication system and method based on mobility and noise uncertainty. The system comprises a signal sender, a signal receiver and a monitoring party, the signal sending party and the monitoring party are provided with single antennas, the receiving party is provided with double antennas, and the signal sending party is used for randomly sending signals in the process of moving along a circular track at a constant speed; the signal receiver is used for receiving a signal in a static state and sending artificial noise of which the power is randomly changed at the same time; the monitoring party is used for detecting whether a communication transmission process exists between the signal sending party and the signal receiving party or not in a static state; the link between the signal sender and the signal receiver is a legal communication link, the link between the signal sender and the monitoring party is a detection link, and the link between the signal receiver and the monitoring party is an interference link.

The invention discloses an anti-covert communication design method based on artificial noise assisted interference, and relates to the technical field of wireless communication. The method comprises the following steps: constructing an anti-covert communication system model with a full-duplex receiver; selecting an illegal information transmitter (Alice), an illegal information receiver (Bob) and a monitor (Willie) as entity research objects of the anti-covert communication system model; constructing two optimization problems: converting an anti-covert communication system model into constructing a listener optimal detection error probability optimization problem and an optimal artificial noise setting optimization problem; the optimization problem is simplified; solving an optimization problem; according to the design method, artificial noise (AN) is emitted in Alice and Bob communication environments to realize anti-covert communication, the optimal detection error probability optimization problem and the optimal artificial noise setting optimization problem are realized, the detection error probability at Willie is reduced, and relatively low noise emission power is used.

The invention discloses a hybrid beam forming method for a communication perception integrated system, and belongs to the technical field of wireless communication. According to the invention, the problem of poor communication security of the traditional ISAC system is solved. According to the method, the sensing signal is endowed with an artificial noise function, so that the eavesdropping process of a potential eavesdropper is effectively interfered on the premise of not reducing the sensing precision, safety communication in a communication sensing integrated system is realized, and the problem of information leakage possibly caused by the direction of a sensing beam is solved; by means of the hybrid beam forming design of communication signals and sensing signals, high-precision target sensing can be achieved in a communication sensing integrated system, meanwhile, safe communication with a cooperative target is guaranteed, by designing a dynamic sub-array division method, the mapping relation between an antenna and a radio frequency chain can be adjusted according to the change of the safety rate, and the communication sensing efficiency is improved. Airspace resources are effectively utilized; and bidirectional matching of the safety rate and the beam forming design is realized. The method can be applied to beam forming of a communication perception integrated system.

The present application provides a communication method and an apparatus. The method comprises: on the basis of a first noise signal, a first device generates a first signal, the first signal being used for sensing or ranging between the first device and a second device, and the first noise signal being used for encrypting the sensing or ranging; and the first device sends the first signal to the second device. In the method, the first device generates a sensing or ranging signal having artificial noise, so that only a specified receiving end (second device) can accurately obtain sensing or ranging information, while if receiving the sensing or ranging signal sent by the first device, other devices cannot calculate the correct sensing or ranging information. Thus, the security of wireless sensing or ranging is improved.

The invention discloses a data security transmission method for a health monitoring system based on rate splitting, which relates to the technical field of data security transmission. The method comprises: utilizing uplink rate splitting multiple access technology and serial interference elimination technology to realize flexible management of co-channel interference and improve data transmission rate; utilizing a base station as a jammer to emit artificial noise to suppress the decoding ability of eavesdropping users in the monitoring system and avoid information leakage; constructing an accurate proxy function for a non-convex confidential transmission rate based on the idea of ​​substitution optimization, and converting the design problem of a non-convex precoding matrix and an artificial noise covariance matrix into an iterative optimization problem; proposing an alternating optimization algorithm to maximize the confidential transmission rate of legitimate users in the system and enhance the secure transmission performance of the health monitoring system.

The present invention discloses a network system combining security and energy load balancing, comprising: Access Points (APs): equipped with N t antennas, with L APs included. The APs are connected to the CPU through wired backhaul links. All APs serve K single-antenna User Equipments (UEs). All APs are equipped with independent Edge Servers (ESs) and form APs-ESs equipped with independent edge servers; Single-antenna attacker Eve: used to intercept legitimate information; The working mode of the APs-ESs and the attacker Eve is the full-duplex mode. The attacker Eve intercepts the uplink transmission through passive eavesdropping and intercepts the downlink transmission through active pilot contamination attacks. The APs-ESs send artificial noise signals to the attacker Eve during the uplink task offloading transmission process to resist passive eavesdropping.

The invention discloses an active monitoring method based on short packet communication, and the method comprises the steps: firstly, building a communication system model which comprises monitoring equipment, a target transmitting end and a target receiving end, transmitting a power-adjustable artificial noise signal by the monitoring equipment, and actively interfering a communication link between the target transmitting end and the target receiving end; then, an optimization problem is established by taking maximization of the average effective monitoring rate of monitoring equipment as an optimization target, and meanwhile, the condition that the average decoding error rate of a target receiving end is maintained at a preset target value is taken as a constraint condition; and finally, solving an optimization problem, determining an optimal transmission rate and corresponding artificial noise transmitting power, and guiding monitoring equipment to perform optimal active monitoring. On the premise of ensuring the communication quality of the target link, a more favorable channel condition is created for the monitoring party, and the monitoring performance is remarkably improved compared with the traditional interference-free passive monitoring scheme and the active monitoring scheme with fixed interference power.

The application discloses a beamforming method of an RIS-aided NOMA-ISAC system against internal and external eavesdropping, which optimizes the transmitting beam of the base station and the phase shift matrix of the RIS intelligently, ensures that the radar sensing requirement is met under the condition of limited energy resources, effectively resists potential internal and external eavesdropping attacks, and thus significantly improves the safe communication performance of the system legal users. Specifically, the method ingeniously uses the radar signal of the base station, performs the radar target sensing task while interfering potential eavesdroppers with the radar signal as artificial noise, and realizes the dual functions of target sensing and safe communication. However, since the optimization problem of minimizing the system legal signal power has non-convex constraints, it is difficult to solve directly, therefore the original problem is decomposed into three sub-problems, and then the semi-positive relaxation technology is used to convert the sub-problems into convex optimization problems, and finally the CVX toolbox is used for alternating optimization solution, which effectively reduces the complexity of the problem and improves the calculation efficiency.

The present invention discloses a MIMO full-duplex secure communication parameter optimization method, an optimization device, and a communication method based on the optimized parameter setting. The parameter optimization method constructs transmission signals of Alice and Bob, adds artificial noise thereto, and performs power allocation and dimension allocation on the effective signal and the artificial noise according to decision variables. At the same time, based on the singular value decomposition of the channel, a specific expression form of the effective signal and the artificial noise is constructed. MIMO full-duplex communication is performed with the constructed transmission signal, and the received signal of each end is obtained. The optimal power allocation coefficient, power allocation matrix, and signal dimension are obtained with the goal of maximizing the system average confidentiality rate. Communication is performed based on the optimized parameters, and the confidentiality performance of the MIMO full-duplex communication system can be improved from the physical layer.

The invention discloses a vehicle task unloading method for known potential eavesdropping vehicle CSI, and belongs to the technical field of communication. In order to solve the problem that sensitive information of a task vehicle may be leaked due to potential eavesdropping behaviors of surrounding vehicles in a scene in which channel state information (CSI) in a system is known, the invention provides a vehicle task unloading method for a known potential eavesdropping vehicle (CSI). According to the method, an artificial noise-assisted adaptive eavesdropping coding technology is adopted, the artificial noise power and the transmitting direction of a base station and the transmitting power of a task vehicle are dynamically adjusted according to the real-time position of a vehicle in a system, wireless channel state information (CSI) and task time delay constraint, and the signal-to-noise ratio of a potential eavesdropping vehicle channel is deteriorated, so that the real-time position of the vehicle is determined. The capacity of an eavesdropping channel is reduced, and the system energy consumption required by task unloading is minimized on the basis of ensuring safe task unloading by increasing the legal channel capacity of a task vehicle and improving the secrecy rate.

The present application provides a method for realizing covert information transmission in a power line network, comprising the following steps: a transmitter prepares covert information to be transmitted to a receiver; the transmitter uses a determined transmission power to send the covert information to the receiver via the power line network; while receiving the transmitter signal, the receiver generates and transmits artificial noise to interfere with the eavesdropper's monitoring; the eavesdropper's false detection probability is evaluated to ensure that the eavesdropper cannot accurately determine whether the transmitter is transmitting information; on the premise of meeting the concealment requirements, the transmitter and receiver maximize the receiver's covert information reception rate by adjusting the transmission power; the covert interruption probability when the receiver receives the signal is analyzed and the concealment is evaluated, and based on the analysis and evaluation results, the system parameters are adjusted to optimize the covert transmission performance; the receiver decodes the received signal to recover the covert information sent by the transmitter; and the integrity and accuracy of the information received by the receiver are verified.