A wireless key generation method based on multipath channel phase random scrambling

Abstract

The present application relates to the technical field of wireless communication, and provides a wireless key generation method based on multipath channel phase random scrambling. The method estimates a multipath channel by transmitting pilot sequences and receiving multipath signals between legal communication parties, and performs random scrambling on the multipath channel, and generates a key by using the scrambled composite channel phase information; and the key can be repeatedly generated and spliced according to the required key length to obtain a final key sequence. The present application uses the multipath channel phase, which is a natural and underutilized "endogenous security resource" in the communication process, to not only improve the key capacity, but also realize the decoupling of security and communication, and to enhance the channel entropy without affecting the communication performance. The method can improve the randomness of the key source while ensuring that the signal-to-noise ratio of the receiving parties remains unchanged, without affecting the normal communication rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and particularly relates to a wireless key generation method based on random scrambling of multipath channel phase. BACKGROUND

[0002] Wireless communication physical layer key generation technology utilizes wireless channel reciprocity, time variation and spatial uniqueness characteristics, and generates a random bit sequence through steps of shared random source acquisition, quantization, information negotiation and privacy amplification. In order to improve the entropy of the shared random source, researchers use spatial diversity technology to retain the multi-dimensional independence of the multipath channel from the perspective of "precise channel recognition", thereby avoiding the entropy reduction caused by the degradation of the multipath channel to a one-dimensional multipath superposition channel. However, in the case of few scattering paths or quasi-static scenarios, the channel is slow or constant, and the randomness of the channel is not fully utilized, resulting in limited key capacity and low key rate. SUMMARY

[0003] In view of the problem that the randomness of the channel is not fully utilized in the prior art, resulting in limited key capacity and low key rate, the present application provides a wireless key generation method based on random scrambling of multipath channel phase, which utilizes the "endogenous security resource" of the multipath channel phase naturally existing in the communication process and not fully exploited, and randomly scrambles the channel, thereby improving the key capacity and rate.

[0004] The wireless key generation method based on random scrambling of multipath channel phase provided by the present application comprises:

[0005] Step 1: the legitimate communication parties send pilot sequences to each other, receive multipath signals, estimate multipath channel parameters according to the multipath signals, and obtain the phase of the multipath channel;

[0006] Step 2: the legitimate communication parties form a transmission pattern and a receiving pattern based on the multipath channel parameters, scramble the phase of the multipath channel based on the transmission pattern and the receiving pattern, and convert the multipath channel into a composite channel;

[0007] Step 3: the legitimate communication parties send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel;

[0008] Step 4: the legitimate communication parties respectively take the phase of the composite channel as a key source, sample and quantize in the same way, and generate a key sequence;

[0009] Step 5: the legitimate communication parties negotiate information on the key sequence, remove or correct the inconsistent bit positions in the key generated by the legitimate communication parties, and obtain a consistent key sequence;

[0010] Step 6: The same privacy amplification algorithm is used to process the consistent key sequence by the legal communication parties, and a final key sequence is obtained.

[0011] Further, the method further comprises: step 7: repeating steps 1-6 multiple times to generate a key sequence meeting the length requirement by splicing.

[0012] Further, in step 1, the angle of arrival estimation value is taken as the multipath channel parameter, and the estimation of the angle of arrival estimation value comprises: searching the multipath angle of arrival in the angle value space based on the multipath channel estimation and the covariance matrix of the received multipath signal, and selecting the angles corresponding to the maximum L peaks as the angle of arrival estimation value, wherein L is the number of multipath channel paths between the communication parties.

[0013] Further, in step 2, the legal communication parties form the transmission pattern and the receiving pattern based on the multipath channel parameter, which comprises: designing the beam forming coefficient based on the angle of arrival estimation value and using the linear constraint minimum variance criterion, and forming the transmission pattern and the receiving pattern based on the beam forming coefficient.

[0014] Further, in step 1, the method and technical route for multipath channel estimation using intelligent information metamaterial single antenna, specifically comprising:

[0015] The signal received by the legal communication parties:

[0016] y km = ω m T A(θ)h BR (θ)s k +n km

[0017] Wherein, y km represents the signal received by the intelligent information metamaterial antenna in the mth fast variation when the kth pilot symbol is transmitted, n km represents the receiving noise, ωm represents the beam forming coefficient, h BR (θ) represents the multipath channel coefficient, s k is the pilot signal sent by Bob, and A(θ) represents the direction vector.

[0018] The M received signals are arranged as a column vector y k :

[0019] y k = h BA s k +n k = Ω T A(θ)h BR (θ)s k +nk

[0020] wherein, represents the pilot signal sent by Bob, Ω = [ω1, … ω M ], n k = [n k1 ,…,n kM ] T ;

[0021] The channel estimation result is obtained by the following formula:

[0022]

[0023] wherein, Y M×K = [y1, …, y K ], s = [s1, …, s K ] T represents the pilot sequence, and F (θ) = Ω T A (θ) is recorded, then

[0024]

[0025] wherein, represents the residual noise, and the estimation of h BR is obtained by solving the following formula:

[0026]

[0027] Further, in step 2, the phase scrambling of the multipath channel in different directions converts the multipath channel into a composite channel, specifically comprising: the legitimate communication parties add different phase disturbances to the multipath in different directions, and the array element pattern ψ n and φ m after adding the disturbance can be represented as:

[0028]

[0029] wherein, ψ n (α i ), φ m (β i ) are the array element direction coefficients of the legitimate communication parties before adding the disturbance, and △θ and represent the phase disturbances added by the legitimate communication parties respectively.

[0030] Further, in step 3, the legitimate communication parties send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel, further comprising: obtaining parameters related to the phase.

[0031] Further, in step 4, or the legitimate communication parties respectively generate keys by using other channel parameters of the composite channel.

[0032] Further, in step 6, SHA256 is used to eliminate the leaked key information to ensure the security of the generated key.

[0033] The beneficial effects of the present application are:

[0034] (1) The present application randomly disturbs the multipath channel phase information in wireless communication, introduces high randomness of the artificial channel, greatly improves the channel key entropy, and the high-entropy key is more difficult to predict, thereby improving the security of data secrecy in wireless communication, and also realizing the decoupling of security and communication, which can enhance the channel entropy without affecting the communication performance.

[0035] (2) The present application enlarges the difference between the legal channel and the eavesdropping channel from the multipath level, which can significantly reduce the correlation between the legal channel and the eavesdropping channel, and provide the security of the channel key.

[0036] (3) The present application randomly disturbs the anisotropic multipath channel phase, and generates a key by using the disturbed composite channel phase information, which can improve the randomness of the key source while keeping the received signal-to-noise ratio unchanged, without affecting the normal communication rate. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A flowchart of a wireless key generation method based on multipath channel phase randomization provided by an embodiment of the present application is shown in the figure;

[0038] Figure 2 A diagram of a wireless key generation method based on multipath channel phase randomization provided by an embodiment of the present application is shown in the figure;

[0039] Figure 3 A diagram of a wireless key generation method based on multipath channel phase randomization provided by an embodiment of the present application is shown in the figure;

[0040] Figure 4 A diagram of a wireless key generation method based on multipath channel phase randomization provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0041] To make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiments of the present application will be described in detail below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0042] The wireless key generation method based on multipath channel phase random scrambling provided by the embodiment of the application can be applied to the following scenarios:

[0043] a. Static or quasi-static communication scenarios, when the wireless channel time variation is poor, the key source randomness is insufficient, and the key rate generated based on the natural wireless channel is low;

[0044] b. Eavesdropping communication scenarios when the eavesdropper approaches, when the eavesdropping channel is related to the legal channel, the security of the key generated based on the natural wireless channel is insufficient, resulting in partial key leakage.

[0045] As shown in Figure 1 , a wireless key generation method based on multipath channel phase random scrambling includes:

[0046] Step 1: The legal communication parties send pilot sequences to each other, receive multipath signals, and estimate multipath channel parameters according to the multipath signals to obtain the phase of the multipath channel.

[0047] Specifically, the legal sender Alice and the legal receiver Bob send channel sounding pilot sequences to each other, receive pilot signals, as shown in Figure 2 , and observe and sample the multipath channel through multiple antennas or smart information metamaterial single antenna, and separate the wireless multipath channel to obtain multipath channel estimation parameters, including multipath channel state information and other parameters related to the multipath angle.

[0048] Specifically, the legal communication parties receive the multipath signals, and realize the multipath channel estimation between the communication parties through the received signals. The least square method can be used to obtain the multipath channel estimation parameters, and the process is represented as:

[0049] wherein, represents the multipath channel estimation between the communication parties Alice and Bob, Y represents the received signal vector, x represents the pilot symbol vector, represents the receiving pattern, α(θ) represents the transmitting pattern, g AB represents the channel gain between the communication parties Alice and Bob, and n represents the noise component.

[0050] Specifically, as shown in Figure 3As shown, the embodiment of the present application combines the above least square method to give a method and technical route for realizing multi-path channel estimation by using intelligent information metamaterial single antenna, assuming that the wireless channel is quasi-static block fading, the channel remains unchanged during the whole channel estimation and subsequent data transmission, and the pilot sequence for channel estimation is composed of K pilot signals. In each pilot signal, the directional pattern of the information metamaterial antenna is changed M times, so that the receiver can obtain KxM sample values, and the whole channel estimation process is completed by using these sample values. In the duration of k pilot symbols, the information metamaterial antenna is changed m times, and the metamaterial antenna state is changed m times, so that

[0051] y km = ω m T A(θ)h BR (θ)s k +n km

[0052] wherein y km represents the signal received by the information metamaterial antenna in the mth fast change when the kth pilot symbol is transmitted, ω m represents the beam forming coefficient, A(θ) represents the direction vector, h BR (θ) represents the multi-path channel coefficient, represents the pilot sequence transmitted by Bob, n km represents the received noise.

[0053] The M received multi-path signals are arranged to generate a column vector y k , that is

[0054] y k = h BA s k +n k = Ω T A(θ)h BR (θ)s k +n k

[0055] wherein Ω = [ω1, … ω M ], n k = [n k1 , …, n kM ] T .

[0056] s k is a known signal, so that the channel estimation algorithms such as LS, MMSE, LMMSE, etc. can be used to obtain h BA . Taking the LS algorithm as an example, the channel estimation result can be obtained by the following formula

[0057]

[0058] where Y M×K = [y1,..., y K ], s = [s1,..., s K ] T represents the pilot sequence.

[0059] In order to recover h from the received signal, we need to estimate h BR . Let F(θ) = Ω T A(θ), then

[0060]

[0061] where represents the residual noise, and F(θ) is a function of θ. Solving the above equation can achieve the estimation of h BR , i.e.

[0062]

[0063] For information metamaterial antennas, the multipath may come from any direction opposite to the array, i.e. θ l ∈ [-π / 2, π / 2]. Sampling [-π / 2, π / 2] with △θ = π / P, we get a sequence denoted as the assumed direction. When the value of P is large enough, the real direction parameter θ l is very close to the assumed direction parameter , and we can estimate h BR (θ) by estimating . At this time, solving the problem becomes:

[0064]

[0065] In order to make the estimation result accurate enough, we solve the above equation by designing an iterative algorithm to obtain the best channel estimation performance.

[0066] Step 2: The legitimate communication parties form a transmission pattern and a receiving pattern based on the multipath channel parameters, and scramble the phase of the multipath channel based on the transmission pattern and the receiving pattern to convert the multipath channel into a composite channel.

[0067] Specifically, the legitimate communication parties form a pattern that simultaneously points to the direction of the multipath space, i.e. a transmission pattern and a receiving pattern, and scramble the phase of the multipath channel in different directions, and the scrambling phase of the multipath channel in different directions is independent and random.

[0068] On the basis of accurately identifying the multipath channel, the transmission end and the receiving end add different phase disturbances to the multipaths in different directions, so that the phase of each multipath channel is randomized. The phase disturbances of the communication parties Alice and Bob are represented as △θ and The array element radiation pattern after adding perturbation can be represented as:

[0069]

[0070] Where ψ n (α1), φ m (β1) represents the element direction coefficients of Alice and Bob before the perturbation was added, respectively, ψ n and φ m This represents the orientation pattern after adding the perturbation.

[0071] Specifically, such as Figure 4 As shown, the composite channel after phase random scrambling is W. R h AB W T W R W T The beamforming coefficients for receiving and transmitting are h, respectively. AB This is the original multipath channel matrix.

[0072] It's understandable that, to maximize channel entropy, Alice and Bob should ensure that the channel parameters are independent for each channel estimation. Therefore, phase scrambling should be coordinated with Alice and Bob's communication process. In this mode, the uplink and downlink channels remain reciprocal for each communication, and the multipath channel phases are independent for each estimation. Thus, the phase of the multipath channel can be used as a random source, resulting in a larger key capacity compared to slowly varying channels.

[0073] Step 3: The two parties in legitimate communication send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel;

[0074] Specifically, while ensuring that the multipath phase scrambling weights remain unchanged, the two legitimate communicating parties exchange pilot sequences to re-estimate the multipath channel and obtain the phase of the composite channel.

[0075] Specifically, Alice and Bob each send pilot probe signals to each other. At a certain moment, Alice sends probe signal SA to Bob. After time t1, Bob successfully receives probe signal YB. Bob then experiences a transmit-receive transition time Δt, while Alice simultaneously experiences a transmit-receive transition time Δt. Then, Bob sends probe signal SB to Alice. After time t2, Alice receives probe signal YA, thus completing one bidirectional channel probe. Assuming the channel coherence time is Tc, to ensure both parties receive highly correlated probe values, one probe cycle must be completed within the coherence time, i.e., t1 + t2 + Δt ≤ Tc.

[0076] Step 4: The legal communication parties respectively take the phase of the composite channel as a key source, and generate key sequences by using the same way of sampling and quantization.

[0077] Specifically, the multiple sequences can be sorted according to the phase information size of the composite channel, and an adaptive quantization algorithm is used to dynamically adjust the quantization level and threshold value, so as to convert the phase information into a shared random source bit sequence. The specific quantization method is determined according to the data analysis of the shared random source.

[0078] Step 5: The legal communication parties negotiate information on the key sequences, remove or correct the inconsistent bits in the key generated by the legal communication parties, and obtain consistent key sequences.

[0079] Specifically, the inconsistent key caused by channel estimation error can be corrected by using an information negotiation method based on BCH coding, convolutional coding, LDPC coding, Polar coding, etc. The Cascade or Winnow algorithm can also be used. The specific quantization method is determined according to the inconsistency rate of the key sequence.

[0080] Step 6: The legal communication parties process the consistent key sequences by using the same privacy amplification algorithm to obtain the final key sequence.

[0081] Specifically, SHA256 can be used to eliminate the leaked key information to ensure the security of the generated key. Other privacy amplification algorithms can also be used.

[0082] Further, based on the method proposed in the above embodiment, the method further comprises: Step 7: Steps 1-6 are repeated multiple times to generate a key sequence that meets the length requirement by splicing.

[0083] Further, in step 3, the legal communication parties send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel. It also includes obtaining parameters related to the phase.

[0084] Correspondingly, in step 4, the legal communication parties generate keys by using other channel parameters of the composite channel.

[0085] The above embodiment is equipped with an array antenna or a smart information metamaterial single antenna, which has the ability to separate wireless multipath channels. It should be noted that one of the legal communication parties is equipped with multiple antennas or a smart information metamaterial single antenna, which has the ability to separate wireless multipath channels. The method of the above embodiment is used to perform multipath channel phase scrambling at the legal communication party, which can also improve the key generation rate and belongs to the scope of the technical solution of the present embodiment.

[0086] The method proposed in this invention utilizes the multipath channel phase, an "intrinsic security resource" that naturally exists in the communication process but has not been fully explored and utilized, to randomly scramble the anisotropic multipath channel phase. The method then uses the scrambled composite channel phase information to generate a key, which not only increases the key capacity and the randomness of the key source, but also ensures that the signal-to-noise ratio received by both communicating parties remains unchanged. This enhances the channel entropy without affecting the communication performance.

[0087] Furthermore, in step 1, the angle of arrival estimate can be used as a multipath channel parameter. The angle of arrival estimate includes: based on the multipath channel estimate and the covariance matrix of the received multipath signal, using the spatial spectrum estimation method to search for the multipath angle of arrival in the angle value space, and selecting the angles corresponding to the largest L peaks as the angle of arrival estimate, where L is the number of multipath channel paths between the two communicating parties.

[0088] Furthermore, in step 2, the two legitimate communicating parties form a transmission pattern and a reception pattern based on multipath channel parameters, including: designing beamforming coefficients based on the estimated angle of arrival and using the linear constraint minimum variance criterion, and forming the transmission pattern and the reception pattern based on the beamforming coefficients.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wireless key generation method based on multipath channel phase random scrambling, characterized in that, include: Step 1: Both parties in legitimate communication send pilot sequences to each other and receive multipath signals; The multipath channel parameters are estimated based on the multipath signal to obtain the phase of the multipath channel; Step 2: The two parties in legitimate communication form a transmission direction pattern and a reception direction pattern based on the multipath channel parameters. Based on the transmission direction pattern and the reception direction pattern, the phase of the multipath channel is scrambled to convert the multipath channel into a composite channel. Step 3: The two parties in legitimate communication send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel; Step 4: Both parties in the legitimate communication use the phase of the composite channel as their key source and perform sampling and quantization in the same way to generate a key sequence; Step 5: The two legitimate communicating parties negotiate the key sequence to remove or correct inconsistent bits in the keys generated by the two legitimate communicating parties, thereby obtaining a consistent key sequence; Step 6: Both parties in the legitimate communication process the consistent key sequence using the same privacy amplification algorithm to obtain the final key sequence.

2. The wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that, The method also includes step 7: repeating steps 1 to 6 multiple times to generate a key sequence that meets the length requirement by splicing.

3. The wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that, In step 1, the estimated angle of arrival is used as the multipath channel parameter. Estimating the estimated angle of arrival includes: based on the multipath channel estimation and the covariance matrix of the received multipath signal, using the spatial spectrum estimation method to search for the multipath angle of arrival in the angle value space, and selecting the angles corresponding to the largest L peaks as the estimated angle of arrival, where L is the number of multipath channel paths between the two communicating parties.

4. The wireless key generation method based on multipath channel phase random scrambling according to claim 3, characterized in that, In step 2, the two legitimate communicating parties form a transmission pattern and a reception pattern based on the multipath channel parameters, including: designing beamforming coefficients based on the estimated angle of arrival and using the linear constraint minimum variance criterion, and forming the transmission pattern and the reception pattern based on the beamforming coefficients.

5. A wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that, Step 1, which utilizes a smart information metamaterial single antenna to achieve multipath channel estimation, specifically includes: Signals received by both parties in legitimate communication: y km =ω m T A(θ)h BR (i)s k +n km Among them, y km This represents the signal received by the information metamaterial antenna during the m-th fast transition when the k-th pilot symbol is transmitted, where n is the signal received by the antenna during the m-th fast transition. km Indicates received noise, ω m h represents the beamforming coefficient. BR (θ) represents the multipath channel coefficient, s k This represents the pilot signal sent by Bob, and A(θ) represents the direction vector. Arrange the M received signals into a column vector y. k : y k =h BA s k +n k =Oh T A(θ)h BR (i)s k +n k in, This represents the pilot signal sent by Bob, Ω=[ω1,…ω M ], n k =[n k1 ,…,n km ] T ; The channel estimation result is obtained by the following formula: Among them, Y M×K =[y1,…,y K ], s=[s1,…,s K ] T Let F(θ) = Ω represent the pilot sequence. T A(θ), then in, To represent residual noise, we can solve the following equation to obtain h. BR Estimate:

6. The wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that, In step 2, the phase scrambling of multipath channels in different directions, converting the multipath channels into composite channels, specifically includes: the two legitimate communicating parties adding different phase perturbations to the multipaths in different directions, and the array element pattern ψ after adding perturbations. n and φ m It can be represented as: Where, ψ n (α i ), φ m (β i ) represent the element direction coefficients, Δθ and Δθ of the two parties in legitimate communication before the perturbation was added. These represent the phase perturbations added by the two parties in legitimate communication.

7. A wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that, In step 3, the two parties in the legitimate communication exchange pilot sequences, estimate the composite channel, and obtain the phase of the composite channel. The step also includes obtaining phase-related parameters.

8. A wireless key generation method based on multipath channel phase random scrambling according to claim 7, characterized in that, In step 4, or the two legitimate communicating parties respectively use other channel parameters of the composite channel to generate a key.

9. A wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that, In step 6, SHA256 is used to eliminate the leaked key information.

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