A Method for Implementing Secure Transmission Based on Flexible Rate Noise Aggregation

Abstract

The present invention discloses a method for implementing secure transmission based on flexible rate noise aggregation, which includes the following steps: During the data transmission process, adaptive modulation transmission is performed according to the channel conditions. The selection of the adaptive modulation signal-to-noise ratio threshold is based on the (3,1,5) convolutional code encoding method, and under different modulation modes, the bit error rate of a single transmission is lower than 10^-3. For data frames with a signal-to-noise ratio greater than or equal to the signal-to-noise ratio threshold Γ th of the data frame, the data frame is securely transmitted as reliable data. After a single transmission of the data frame, the destination node Bob caches the correctly decoded frame data into the endogenous key storage pool as a key, and then through Hash processing, the final secure key is generated; for data frames with a signal-to-noise ratio less than the signal-to-noise ratio threshold Γ th of the data frame, the data frame is protected with the secure key and then retransmitted until the received signal-to-noise ratio of the data frame reaches the signal-to-noise ratio threshold of the corresponding modulation method. This method can effectively improve the security of information transmission.

Description

Technical Field

[0001] The present invention belongs to the field of wireless information transmission security and relates to a method for realizing secure transmission based on flexible rate noise aggregation. Background Art

[0002] With the advent of the first year of large-scale new infrastructure construction, the explosive growth of the mobile Internet of Things has officially begun. In the future, the mobile Internet of Things ecosystem will be clearer in terms of scenario division, technical pattern, and industrial chain organization, and the industrial comprehensive ecosystem is facing major changes. For example, in scenarios with high-rate transmission requirements, such as the vehicle Internet of Things, intelligent healthcare, video surveillance, intelligent manufacturing, etc. In low-rate transmission scenarios, wearable devices, industrial manufacturing, energy meters, fire smoke detectors, intelligent logistics, etc., as well as flexible-rate transmission scenarios. In recent years, industrial information has shown explosive growth, and the large amount of data generated during the industrial production process poses a challenge to the industrial Internet of Things. How to securely transmit, effectively process, and analyze this data is the core and also the difficulty of the industrial Internet of Things. Industrial Internet of Things security mainly involves processes such as data acquisition security and network transmission security. Information security plays a key role in enterprise operations. For example, in industries such as metallurgy, coal, and petroleum, data collection and transmission require long-term continuous operation. How to ensure the accuracy of information during data transmission is a prerequisite for the application of the industrial Internet of Things in actual production.

[0003] However, compared with wired communication systems, the wireless communication system faces relatively higher security threats. Firstly, the physical transmission medium of the wireless communication system is open, and its broadcast characteristics during propagation make it easy to be eavesdropped on and interfered with. Secondly, the wireless terminal devices have certain random movement characteristics, resulting in extremely difficult security management. Thirdly, the instability of wireless transmission also causes the reliability and effectiveness of the system to be interfered with to varying degrees. Therefore, ensuring the security of data transmission in the industrial Internet of Things while achieving high-rate transmission is also a problem that urgently needs to be solved.

[0004] Physical layer security is a technology different from the traditional method of ensuring information security by increasing computational complexity. Its core idea is to start from the perspective of information theory and utilize the randomness of the wireless channel to achieve the purpose of secure transmission. Research on physical layer security can start from the direction of secure coding. When the channel quality of the legitimate link is better than that of the eavesdropping link, the secure transmission of information can be theoretically ensured. With the emergence of channel coding with extremely strong decoding performance, combining high-performance channel coding as the mother code with the characteristics of the wireless transmission system has become a research hotspot for secure coding in recent years.

[0005] Existing noise aggregation schemes can utilize the inherent noise in a wireless communication system to reduce the eavesdropping ability of eavesdropping users, convert harmful noise into available resources, and achieve the purpose of secure transmission. However, existing noise aggregation schemes still have many limitations. First, existing schemes do not make real-time adjustments to data transmission in combination with actual channel conditions. Second, if the eavesdropping receiver almost correctly receives the first frame of data packets, the probability of error in the aggregated second frame of data packets is limited. All of the above will result in a limited difference in decoding performance between the legitimate receiving end and the illegal eavesdropping receiving end, and poor security of information transmission. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a method for realizing secure transmission of noise aggregation based on flexible rate, which can effectively improve the security of information transmission.

[0007] To achieve the above purpose, the method for realizing secure transmission of noise aggregation based on flexible rate described in the present invention includes the following steps:

[0008] During the data transmission process, for data frames with a signal-to-noise ratio greater than or equal to the signal-to-noise ratio threshold Γ th of the data frame, the data frame is securely transmitted as reliable data. After a single transmission of the data frame, the destination node Bob caches the correctly decoded frame data into the endogenous key storage pool as a key, and then through Hash processing, generates the final security key; for data frames with a signal-to-noise ratio less than the signal-to-noise ratio threshold Γ th of the data frame, the data frame is protected with the security key and then retransmitted until the received signal-to-noise ratio of the data frame reaches the signal-to-noise ratio threshold of the corresponding modulation method.

[0009] The setting rule of the signal-to-noise ratio threshold Γ th is: to make the key data entering the storage pool equivalent to the consumption.

[0010] When γ≥Γ th , and the destination node Bob decodes the data frame correctly in one transmission, the data frame is put into the storage pool, otherwise, the data frame is not put into the storage pool.

[0011] The key threshold Γ th simultaneously satisfies γ th,j ≤Γ th <γ th,j+1 , and the average throughput of the system key data is as:

[0012]

[0013] where P k is the probability of selecting the k-th modulation method, P j,yand P j,n They are the probabilities of being able to and not being able to select the j-th modulation method respectively.

[0014] The average throughput consumed by the key data is:

[0015]

[0016] The present invention has the following beneficial effects:

[0017] When the method for implementing flexible rate-based noise aggregation secure transmission according to the present invention is specifically operated, a signal-to-noise ratio threshold Γ th is used to classify data frames. The data frames that meet the requirements are cached into the endogenous key storage pool as keys, and then after Hash processing, the final secure key is generated. After the hash isolation operation, the key soft information cannot be transmitted to the protected data, that is, the soft information is isolated. For the destination node Bob, the received correct key hard information can still be used to perform soft decision decoding on the protected data. For the illegal eavesdropping receiver Eve, once there is a single-bit decoding error in the key data frame, the result of the hashed data frame will be all wrong, that is, the hard decision decoding error is amplified. Using this information to decode the protected data will increase the decoding error rate of the protected data. At the same time, the high-order modulation transmission under high signal-to-noise ratio of the legitimate receiving link increases the difficulty of correct decoding for Eve. Therefore, the present invention can greatly deteriorate the receiving situation of Eve without increasing the decoding complexity and ensure that Bob correctly receives the private information to improve the security of information transmission. Description of the Drawings

[0018] Figure 1 It is a system model diagram of the noise aggregation secure transmission scheme;

[0019] Figure 2 It is a structural diagram of the transmitter;

[0020] Figure 3 It is a structural diagram of the legitimate receiver;

[0021] Figure 4 It is a structural diagram of the eavesdropping receiver;

[0022] Figure 5 It is a flowchart of the soft decision decoding;

[0023] Figure 6 It is a convolutional code and equivalent model diagram;

[0024] Figure 7 It is a curve graph of the single-frame maximum likelihood hard decision error rate;

[0025] Figure 8 It is a curve graph of the single-frame maximum likelihood soft decision error rate;

[0026] Figure 9 The interception rate of Eve and the system throughput versus Γ th variation diagram;

[0027] Figure 10 is the distribution diagram of the frame error rate of the flexible rate noise aggregation secure transmission based on convolutional codes;

[0028] Figure 11 is the distribution diagram of the bit error rate of the flexible rate noise aggregation secure transmission based on convolutional codes;

[0029] Figure 12 is the comparison diagram of the frame error rate of multiple one-time pads VS one-time pad;

[0030] Figure 13 is the comparison diagram of the bit error rate of multiple one-time pads VS one-time pad;

[0031] Figure 14 is the performance curve diagram of Eve's equivalent convolutional code decoding. Detailed implementation manners

[0032] In order to enable those skilled in the art of the present technology to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present invention disclosure. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0033] The structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0034] The implementation method of the flexible rate-based noise aggregation secure transmission according to the present invention includes the following steps:

[0035] The system model of the flexible rate-based noise aggregation secure transmission scheme is as Figure 1As shown in the figure, the system model includes a single source transmitter node Alice, a single legitimate destination node Bob, and a single illegal eavesdropping node Eve. In addition to the legitimate link in the system model, there is also a noiseless feedback link between Alice and Bob, and the selective repeat ARQ protocol is used between Alice and Bob. In the presence of the illegal eavesdropping node Eve, Alice needs to transmit information privately and reliably to Bob. The channels are independent of each other, indicating that there is a possibility that the quality of the eavesdropping channel is better than that of the legitimate channel. However, both the feedback link and the Hash (information isolation unit) isolation can ensure transmission reliability. Bob can request the transmitter to retransmit the wrong or lost frames through the feedback link to ensure correct data reception, while Eve cannot perform similar operations. After the Hash isolation operation, the key soft information cannot be transmitted to the protected data, but the hard information, that is, the soft information is isolated. For Bob, the key can still be used to perform soft decision decoding on the protected data with the obtained correct hard information. For the Eve side, once there is a single-bit decoding error in the key, the 01 result of its reverse Hash will be all wrong, that is, the hard decision decoding error is amplified. Using this information to decode the protected data will increase the bit error rate of the protected data decoding.

[0036] As Figure 2 shown in the transmitter structure of the transmission system, during the data transmission process, for the data frames with good signal-to-noise ratio, first, this frame is securely transmitted as reliable data without retransmission. For the frame data correctly decoded by Bob after a single transmission of this frame, it is cached into the endogenous key storage pool as a key, and after performing the Hash operation, confidentiality enhancement is achieved and the final secure key is generated. For the data frames with poor signal-to-noise ratio, the secure key is used to protect this frame. After the transmission of this frame data is completed, the key is discarded. As long as the signal-to-interference-plus-noise ratio threshold for data type discrimination is selected appropriately, it can be ensured that the statistical average of the key data and the protected data is equal in throughput, thus ensuring uninterrupted transmission of the system and supporting real-time services such as video conferencing and online education. For the legitimate receiving end, although the SHA-512 Hash function isolates the key soft information, only the correctly decoded data of Bob when the legitimate channel condition is good is cached as the key, and the protected data can also be correctly decrypted according to the key. For the eavesdropping receiver Eve, it can neither use the soft information to decode the protected data nor use the hard decoding method for decoding.

[0037] ARQ control unit: The legitimate receiver Bob sends ACK / NACK signals through the feedback link to inform the transmitter Alice of the successfully received frames or the lost or incorrect frames that require retransmission, and controls the retransmission of data frames. However, the illegal eavesdropping receiver Eve cannot provide feedback, thus deteriorating its equivalent channel quality and further enhancing the secure transmission. The criterion for protecting data retransmission is that the received signal-to-noise ratio of this frame does not reach the threshold value. The reason why the protected data can be retransmitted is that even if the eavesdropping receiver Eve correctly receives the protected data, it cannot decrypt it because it does not know the key.

[0038] Rate control data framing unit: Frames the amount of data to be transmitted according to the adaptive modulation mechanism to adapt to the channel conditions.

[0039] Information isolation rate matching unit: Performs SHA-512 Hash operation on the key storage pool data to isolate the key soft information and increase the hard decision decoding error of this frame for the eavesdropping receiver.

[0040] Switch controller unit: The legitimate receiver Bob estimates the channel conditions of the legitimate channel and feeds back the current receiver signal-to-noise ratio γ, Γ to the transmitter Alice th is the discrimination threshold for judging the data type of this frame. When γ < Γ th , then the key data in the endogenous resource pool is used to protect this frame of data after SHA512 operation (secure self-protection) and then transmitted. Otherwise, it is stored in the endogenous key storage pool.

[0041] Adaptive modulation controller unit: According to different channel conditions, different signal modulation methods are adopted. In practice, the modulation orders that can be used in adaptive modulation are discrete values. Assume that there are K modulation modes that can be used in the system. Correspondingly, there are K + 1 signal-to-noise ratio threshold values (γ th，0 , γ th，1 ,..., γ th，K , γ th，K+1 ), where γ th，0 = 0, γ th，K+1 = ∞. The transmitter receives the feedback to obtain the current receiver signal-to-noise ratio γ. When γ th，k ≤ γ < γ th，k+1 , then the kth modulation mode is selected. bk represents the number of bits per symbol under various modulation methods, and mk represents the order under various modulation methods. Then there is b k = log2(m k ). The 0th modulation mode represents no transmission. γ th，kThe selection criterion is that the bit error rate of maximum likelihood hard demodulation or maximum likelihood soft demodulation under the corresponding modulation method during single-frame data transmission reaches at least a certain BER threshold. For example, taking 10^-3 as the boundary, the present invention designs a combined transmission of 3 modulation methods, namely QPSK, 16QAM, and 64QAM. The parameters of the modulation methods are shown in Table 1 below, where No-Tx means no transmission:

[0042] Table 1

[0043]

[0044] Endogenous key storage pool unit: In a mobile wireless environment, when there is no direct path between the transmitter and the receiver, each path can be modeled as a Rayleigh fading process. The probability density function f(γ) of the instantaneous signal-to-noise ratio of the Rayleigh fading channel is:

[0045]

[0046] where is the average signal-to-noise ratio. The condition for entering the endogenous resource pool is: when γ≥Γ th , and the frame is correctly decoded by Bob in one transmission, then it is put into the storage pool; otherwise, it is not put into the storage pool. Assume that the key threshold Γ th simultaneously satisfies γ th,j ≤Γ th <γ th,j+1 , then the average throughput of the system key data is in units of bits per symbol (bit / symbol):

[0047]

[0048] where P k is the probability of selecting the k-th modulation method, P j,y and P j,n are the probabilities of possibly and impossibly selecting the j-th modulation method respectively. Then the average throughput consumed by the key data is:

[0049]

[0050] The one-time pad encryption algorithm has been proven by Shannon to be perfectly secure, that is, information-theoretically secure, or unconditionally secure. To ensure the realizability of the one-time pad, the determination criterion of Γ th is that the key data entering the storage pool is basically equivalent to the consumption, that is In the present invention, the case of multiple one-time pads is also considered. That is, the determination criterion of Γ th is that the data entering the storage pool is less than the consumption, that is

[0051] What happens when the number of bits of the key is inconsistent with the number of bits of the protected data? Among them, when the number of bits input to the Hash function at one time increases, while the number of bits of the Hash output is fixed. This is equivalent to encrypting one bit of data with multiple bits, and such security is relatively strong. When the protection ability is weak. In the extreme case, one bit of data is used to encrypt one frame of data, and the eavesdropping receiver can use brute force to obtain the private information. One bit is either 0 or 1, and only an even trial is needed.

[0052] Although in theory, the data entering the storage pool is controlled to be basically equivalent to or in a multiple relationship with the consumption, the randomness of the channel makes it possible for the data in the storage pool to be consumed. At this time, the protected data is not transmitted until the key storage pool is not empty.

[0053] As Figure 3 shown in the legal receiver structure, for the received valid frame data, the screening control unit first determines whether the received valid frame data is a candidate key or encrypted data according to the channel conditions. When it is a candidate key, demodulation, channel decoding processes are performed, and ACK / NACK and CSI are fed back. The correctly decoded data frame is stored as a key in the endogenous key storage pool. When it is encrypted data, the data is cached, demodulated after maximum ratio combining, and the data is decrypted and channel decoded using the data in the key storage pool. When all the confidential information is correctly received, the reception stops.

[0054] As Figure 4 shown in the eavesdropping receiver structure, since the eavesdropping receiver fully understands the coding and decoding schemes and encryption protocols in the transmission process, etc., its receiver structure is almost the same as that of the legal receiver, except that it cannot feedback to the legal transmitter. As an illegal eavesdropper, it can only perform passive reception. The Hash operation isolates the key soft information and amplifies the hard decoding error. For the eavesdropping receiver, it can neither use the key soft information to decode the protected data frame nor use the hard decoding method to decode. That is, the Hash operation is equivalent to amplifying the noise for the eavesdropping receiver; when the eavesdropping receiver does not receive valid frame data for a long time, it is considered that the eavesdropping receiver no longer continues to transmit confidential information and stops receiving.

[0055] In the present invention, the legitimate receiver Bob mainly selects the soft - decision method for decoding. Hard - decision decoding decodes based on the minimum Hamming distance. Specifically, first, the received signal is hard - demodulated and decided as 0 or 1 bit, and then through channel decoding, the code segment with the minimum Hamming distance among the received code segment and all possible code segments is output. Its disadvantage is that some information is discarded. However, in soft - decision decoding, the maximum - likelihood decoding based on Euclidean distance can utilize the information ignored by hard - decision, decode more accurately, thereby reducing the bit - error rate and improving the reliability. Although compared with hard - decision decoding, soft - decision decoding can increase the coding gain by 3 dB, it is accompanied by a higher computational complexity. Therefore, the present invention selects the log - likelihood ratio as the decision metric. The specific soft - decision decoding process is as follows Figure 5 as shown below:

[0056] Received signal The subscript j represents the j - th branch, m represents the m - th bit of this branch, and the superscript * represents the optimal path. First, the received signal is soft - demodulated, and the log - likelihood ratio of the soft information of each bit is output. Assume that K bits are mapped to l symbols, and the symbol set is Ω = 2 K , z i is Gaussian noise, h is the corresponding channel coefficient, and there are b1, b2,..., b K bits. Then the observed sample r is:

[0057]

[0058] For the received signal of one transmission, when the transmitted symbol is s l , the probability that the received signal is r satisfies:

[0059]

[0060] where, is the variance of additive Gaussian noise, then the log - likelihood ratio of the posterior probability at this time is:

[0061]

[0062] where, is the set of constellation points corresponding to b i = 1, is the set of constellation points corresponding to b i = 0.

[0063] Then the soft information of each bit is:

[0064]

[0065] For the obtained soft - information sequence, input it into the Viterbi algorithm for channel decoding.

[0066] However, since the protected data is encrypted at the transmitting end, its maximum a posteriori log-likelihood ratio is related to the key data. Considering the independence of the received symbol noise in the codeword, the following analysis assumes that only one bit of information is contained in one frame. According to the transmission protocol, the encrypted data frame a is composed of the exclusive OR of two parts. Among them, the first part is the result of the Hash operation on the key data frame, denoted as a0, and the second part is the current protected data frame itself, denoted as b0. Then the decoding rule for the protected data frame at this time is Since only the data frames correctly decoded by Bob are cached as keys, the legitimate receiving end knows the completely correct key data. After the Hash operation is performed again, the data a0 is obtained, that is, Bob knows whether a0 is 0 or 1 at this time. For soft-decision decoding of the protected data, the relationship between the log-likelihood ratio of the encrypted transmitted data a and the original protected data b0 needs to be calculated, then there is

[0067]

[0068] Since the legitimate receiving end knows whether a0 is 0 or 1 when decrypting the key, then there is

[0069]

[0070] Among them, λ a and are the posterior probability likelihood ratios of the encrypted transmitted data and the protected data respectively. At the Bob side, a0 will not be in error, that is, Bob knows a0 when decoding b0. However, Eve can only passively receive and cannot guarantee the correct decoding of the key data. After the Hash operation is performed again, any single-bit error will cause the hashed a0 to be in error, and then the decoding error of the protected data will also increase.

[0071] Considering the equivalent convolutional code decoding method triggered when the eavesdropper cannot know the key data in the case of one-time pad encryption multiple times. Without loss of generality, consider the case of two-time pad encryption. The transmitter sends two frames of protected data frames a and b encrypted using the key data frame s respectively. That is, the eavesdropping receiver Eve performs maximum likelihood hard demodulation on the received results respectively to obtain the results Eve XORs the two frames of demodulated data again to obtain At this time, the XOR result is input into the equivalent convolutional code Viterbi decoding algorithm, and the cross results [a0, b0, a1, b1,..., a n , b n of the protected data frames a and b can be obtained. Specifically, the original convolutional code model and the equivalent convolutional code model are as Figure 6As shown. The exclusive-OR operation of the original convolutional code encoding system and the exclusive-OR operation between two frames of data are combined into one. The equivalent convolutional code encoding model is actually a model with a constraint length, an output length the same as that of the original convolutional code model, and an input length twice that of the original convolutional code model. The generator vectors of the output data of the original model are represented as: g1 =

[10101] , g2 =

[11011] , g3 =

[11111] . Then the generator vectors of the output data of the equivalent model are represented as g1 = [1100110011], g2 = [1111001111], g3 = [1111111111]. Since maximum likelihood hard demodulation is used during demodulation, the received signal-to-noise ratio thresholds SNR th1 , SNRth2 are respectively selected as SNR th1 = 6dB, SNR th2 = 10dB.

[0072] Example 1

[0073] To evaluate the present invention, simulation analysis was carried out. It is assumed that both the legitimate receiving end Bob and the illegal eavesdropping receiving end Eve fully understand the encoding and decoding schemes and related transmission protocols, and the maximum a posteriori probability log-likelihood ratio is used as the decision metric for the received signals, that is, soft decision decoding. The relevant simulation parameter settings are shown in Tables 1, 2, and 3 as follows:

[0074] Table 1

[0075]

[0076] Table 2

[0077]

[0078] Table 3

[0079]

[0080] Considering the corresponding modulation QPSK, 16QAM, and 64QAM modes, a data frame contains 512, 1024, 1536 bits of data, and the total number of data frames is 10000. Both Bob and Eve adopt maximum likelihood soft decision decoding. When the main channel condition γ > Γ th , and Bob correctly receives this frame and caches it as a key, otherwise, it is not cached, that is, when Alice does not receive the ACK frame feedback from Bob, the frame data is not cached as key data; when the main channel condition γ < Γ th , the protected data is protected and transmitted after key hashing, and the retransmission condition is that the received signal-to-noise ratio is higher than the threshold of the corresponding modulation mode. During the simulation process, the channel follows quasi-static independent Rayleigh fading, and the noise is Gaussian additive white noise.

[0081] The simulation verification results of the present invention are as follows Figures 7 to 14 shown Figure 7 is the maximum likelihood hard demodulation bit error rate curve of a single-frame data packet under different modulation modes. The modulation mode selection rule is: according to the output signal-to-noise ratio SNR of the first transmission of this frame of data and the threshold signal-to-noise ratio SNR th1 , SNR th2 comparison result, when SNR < SNR th1 , then adopt the low-order QPSK modulation mode; when SNR th1 < SNR < SNR th2 , then adopt the 16QAM modulation mode; when SNR > SNR th2 , then adopt the high-order 64QAM modulation mode. The selection of the adaptive modulation signal-to-noise ratio threshold is based on the (3,1,5) convolutional code encoding mode and the bit error rate curves of single transmissions under different modulation modes. As Figure 7 shown, taking the bit error rate below 10^-3 as the standard, then SNR th1 and SNR th2 values are respectively selected as SNR th1 = 6dB, SNR th2 = 10dB. It should be noted that the received signal-to-noise ratio of the protected data should be higher than this threshold value under the corresponding modulation mode. When the received signal-to-noise ratio of the protected data is lower than the threshold value under the corresponding modulation mode at this time, then retransmit the protected data until the received signal-to-noise ratio after maximum ratio combining is higher than the corresponding threshold value.

[0082] Figure 8 represents the maximum likelihood soft demodulation (soft information decoding) bit error rate curve of a single-frame data packet under different modulation modes. At this time, SNR th1 = 3dB, SNR th2 = 7dB.

[0083] Figure 9 represents the variation of the Eve interception rate and the system throughput with the data type discrimination threshold Γ th . As Γ th increases, the Eve interception rate decreases, the system security increases, but the throughput decreases. For different application scenarios, different discrimination thresholds can be selected to meet different interception rate and throughput requirements. (Under the same data volume, use the relative value of the transmission time as a reference for the throughput) Set the channel average signal-to-noise ratio to 15dB.

[0084] Figure 10Denote the frame error rate of Bob and Eve based on the flexible rate noise aggregation scheme in the one-time pad scenario. In the present invention, in the low signal-to-noise ratio range (1 dB - 9 dB), the frame error rate of Eve always remains at 0.9, which means that it is almost impossible to correctly decode any secure data frame, thus proving the reliability and security of this secure transmission scheme. However, the frame error rate cannot fully prove the actual reception effect because an error in one bit of data will result in an error in this frame of data. Therefore, the bit error rate of this secure transmission scheme is further analyzed.

[0085] Figure 11 Denote the bit error rate of Bob and Eve based on the flexible rate noise aggregation scheme in the one-time pad scenario. From Figure 11 It can be seen that the decoding performance gap between Bob and Eve is extremely large. Eve can hardly recover the information without error. When the signal-to-noise ratio is low, the transmitter Alice mainly adopts a low code rate modulation method. As the signal-to-noise ratio increases, the probability of the transmitter Alice adopting a high code rate modulation method continuously increases. When the main channel condition of Bob is good at this time and a high code rate modulation method is adopted, and the illegal eavesdropping channel is bad and cannot correctly decipher the key data under the high code rate modulation method, it will lead to the inability to decipher the corresponding protected data either. The decoding performance of the eavesdropping end drops sharply. Even if Eve regains the channel advantage in the corresponding protected data frame, but because the corresponding key data is not correctly decoded, it affects the decoding of this frame of protected data. Therefore, the legitimate receiving end can regain the channel advantage through the present invention.

[0086] Examine the security performance issues of the multi-time pad and the one-time pad when the system throughput is the same (that is, for the multi-time pad and the one-time pad, the th selection criteria are both to ensure that the key data entering the storage pool is always sufficient). Without loss of generality, examine the situation. Figure 12 and 13 Denote the frame error rate and bit error rate of the multi-time pad and the one-time pad respectively. When the throughput is the same, the security performance of the multi-time pad scheme degrades.

[0087] Figure 14 Denote the frame error rate and bit error rate curves when the equivalent convolutional code decoding method is adopted in the case that the eavesdropping end Eve cannot obtain the key data.

Claims

1. A method for implementing secure transmission of noise aggregation based on flexible rate, characterized in that Comprising the following steps: During the data transmission process, for data frames with a signal-to-noise ratio greater than or equal to the signal-to-noise ratio threshold Γ th of the data frame, the data frame is used as reliable data for secure transmission. After a single transmission of the data frame, the destination node Bob caches the correctly decoded frame data into the endogenous key storage pool as a key, and then through Hash processing, generates the final secure key; For a data frame with a signal-to-noise ratio less than the signal-to-noise ratio threshold Γ th the data frame is protected using a security key and then retransmitted until the received signal-to-noise ratio of the data frame reaches the signal-to-noise ratio threshold of the corresponding modulation method; Signal-to-noise ratio threshold Γ th The setting rule is: make the key data entering the storage pool equivalent to the consumption.

2. The method for implementing secure transmission of noise aggregation based on flexible rate according to claim 1, wherein It means that the key data entering the storage pool is equivalent to the consumed one. When γ≥Γ th , and the destination node Bob decodes the data frame correctly in one transmission, then the data frame is put into the storage pool; otherwise, the data frame is not put into the storage pool.

3. The method for implementing secure transmission of noise aggregation based on flexible rate according to claim 2, wherein Key threshold Γ th While satisfying γ th,j ≤ Γ th <γ th,j+1 , the average throughput of the system key data is as follows: where, P k is the probability of selecting the k-th modulation scheme, P j,y and P j,n are the probabilities of possibly and impossibly selecting the j-th modulation scheme, respectively, b k represents the number of bits per symbol under the k-th modulation scheme, b j represents the number of bits per symbol under the j-th modulation scheme, f(γ) is the probability density function of the instantaneous signal-to-noise ratio of the Rayleigh fading channel, and σ 2 is the variance of the additive Gaussian noise.

4. The method for implementing secure transmission of noise aggregation based on flexible rate according to claim 3, characterized in that Average throughput consumed by key data is as follows:

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