Wireless key generation method based on multipath channel phase random scrambling

Abstract

The invention relates to the technical field of wireless communication, and provides a wireless key generation method based on multipath channel phase random scrambling. According to the method, two legal communication parties mutually send pilot frequency sequences and receive multipath signals to estimate a multipath channel, random scrambling is carried out on the multipath channel, and a secret key is generated by using scrambled composite channel phase information; and the secret keys can be repeatedly generated according to the required secret key length and are spliced to obtain a final secret key sequence. According to the method and the device, by utilizing the'endogenous security resource 'which naturally exists in the communication process and is not fully mined and utilized, not only can the key capacity be improved, but also the decoupling of security and communication is realized, and the communication performance is not influenced while the channel entropy is enhanced. According to the method, while the randomness of the key source is improved, the receiving signal-to-noise ratio of two communication parties can be ensured to be unchanged, and the normal communication rate is not influenced.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a wireless key generation method based on multipath channel phase random scrambling. Background Art

[0002] Wireless communication physical layer key generation technology utilizes the reciprocity, time-varying and spatial uniqueness of wireless channels to generate random bit sequences through steps such as shared random source acquisition, quantization, information negotiation and privacy amplification. In order to improve the entropy of shared random sources, some researchers have used spatial diversity technology to retain the multi-dimensional independence of multipath channels from the perspective of "precisely understanding the channel", thereby avoiding the entropy reduction caused by the multipath channel degenerating into a one-dimensional multipath superposition channel. However, in scenarios with few channel scattering paths or quasi-static conditions, the channel is in a slowly changing or unchanged state, and the randomness of the channel is not fully utilized, resulting in limited key capacity and low key rate. Summary of the invention

[0003] In view of the problem in the prior art that the randomness of the channel is not fully utilized, resulting in limited key capacity and reduced key rate, the present invention provides a wireless key generation method based on multipath channel phase random scrambling. By utilizing the multipath channel phase, an "intrinsic security resource" that naturally exists in the communication process and is not fully exploited, the channel is randomly scrambled, which can improve the key capacity and rate.

[0004] The present invention provides a wireless key generation method based on multipath channel phase random scrambling, comprising:

[0005] Step 1: The two legal communicating parties send pilot sequences to each other and receive multipath signals; and estimate multipath channel parameters based on the multipath signals to obtain the phase of the multipath channel;

[0006] Step 2: The legitimate communicating parties form a transmission directional diagram and a reception directional diagram based on the multipath channel parameters, scramble the phase of the multipath channel based on the transmission directional diagram and the reception directional diagram, and convert the multipath channel into a composite channel;

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

[0008] Step 4: The two legitimate communicating parties respectively use the phase of the composite channel as a key source, perform sampling and quantization in the same manner, and generate a key sequence;

[0009] Step 5: The legitimate communicating parties negotiate information on the key sequence, remove or correct inconsistent bits in the keys generated by the legitimate communicating parties, and obtain a consistent key sequence;

[0010] Step 6: The legitimate communicating parties use the same privacy amplification algorithm to process the consistent key sequence to obtain the final key sequence.

[0011] Furthermore, 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.

[0012] Furthermore, in step 1, the arrival angle estimation value is used as the multipath channel parameter, and estimating the arrival angle estimation value 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 arrival angle in the angle value space, and selecting the angles corresponding to the largest L peaks as the arrival angle estimation value, where L is the number of multipath channel paths between the communicating parties.

[0013] Furthermore, in step 2, the legal communicating parties form a transmission pattern and a reception pattern based on the multipath channel parameters, including: designing beamforming coefficients based on the arrival angle estimation value and using a linear constrained minimum variance criterion, and forming a transmission pattern and a reception pattern based on the beamforming coefficients.

[0014] Furthermore, in step 1, the method and technical route for realizing multipath channel estimation using a single antenna of a smart information metamaterial specifically include:

[0015] Signals received by both parties in legitimate communication:

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

[0017] Among them, y km represents the signal received by the information metamaterial antenna at the mth fast change when sending the kth pilot symbol, n km Indicates the received noise, ωm represents the beamforming coefficient, h BR (θ) represents the multipath channel coefficient, s k is the pilot signal sent by Bob, A(θ) represents the direction vector;

[0018] Arrange the M received signals into 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] in, 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] Among them, Y M×K =[y1,…,y K ],s=[s1,…,s K ] T Denotes the pilot sequence, and F(θ)=Ω T A(θ), then

[0024]

[0025] in, represents the residual noise, and solving the following equation yields h BR Estimates:

[0026]

[0027] Furthermore, in step 2, the phase scrambling of the multipath channels in different directions converts the multipath channels into composite channels, specifically including: the legitimate communication parties add different phase perturbations to the multipaths in different directions, and the array element directional pattern ψ after the perturbation is added n and φ m It can be expressed as:

[0028]

[0029] Among them, ψ n (α i ),φ m (β i ) are the array element directional coefficients of the two legal communicating parties before adding disturbances, △θ and They respectively represent the phase disturbances added by the legitimate communicating parties.

[0030] Furthermore, in step 3, the legal communicating parties send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel, which also includes: obtaining parameters related to the phase.

[0031] Furthermore, in step 4, the two legal communicating parties may respectively use other channel parameters of the composite channel to generate keys.

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

[0033] Beneficial effects of the present invention:

[0034] (1) The present invention randomly perturbs the phase information of multipath channels in wireless communications. The introduced artificial channel has high randomness, the channel key entropy is further improved, and the key with high entropy value is more difficult to predict, thereby improving the security of data confidentiality in wireless communications. At the same time, it also realizes the decoupling of security and communication, and can enhance the channel entropy without affecting the communication performance.

[0035] (2) The present invention widens the difference between the legitimate channel and the eavesdropping channel from the multipath level, which can significantly reduce the correlation between the legitimate channel and the eavesdropping channel and improve the security of the channel key.

[0036] (3) The present invention performs random scrambling on the anisotropic multipath channel phase and generates a key using the scrambled composite channel phase information. This method can improve the randomness of the key source while ensuring that the receiving signal-to-noise ratio of both communicating parties remains unchanged and does not affect the normal communication rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of a flow chart of a wireless key generation method based on multipath channel phase random scrambling provided by an embodiment of the present invention;

[0038] Figure 2 A wireless key generation method based on multipath channel phase random scrambling provided by an embodiment of the present invention is a directional diagram of receiving a multipath signal;

[0039] Figure 3 A schematic diagram of a composite channel constructed by artificial random scrambling of a wireless key generation method based on multipath channel phase random scrambling provided by an embodiment of the present invention;

[0040] Figure 4 A schematic flow chart of a multipath phase randomization scheme of a wireless key generation method based on multipath channel phase random scrambling provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0043] a. Static or quasi-static communication scenarios, in which the wireless channel has poor time-varying properties, the key source is not random enough, and the key rate generated based on the natural wireless channel is low;

[0044] b. The eavesdropper approaches and eavesdrops on the communication scenario. At this time, the eavesdropping channel is related to the legitimate channel. The key generated based on the natural wireless channel is not secure enough, resulting in partial key leakage.

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

[0046] Step 1: The two legal communicating parties send pilot sequences to each other and receive multipath signals; and estimate the multipath channel parameters based on the multipath signals to obtain the phase of the multipath channel.

[0047] Specifically, the legitimate sender Alice and the legitimate receiver Bob send channel detection pilot sequences to each other and receive pilot signals, such as Figure 2 As shown, the multipath channel is observed and sampled by multiple antennas or a single antenna of an intelligent information metamaterial and the wireless multipath channel is separated to obtain multipath channel estimation parameters, including multipath channel state information and other parameters related to the multipath angle.

[0048] Specifically, the two legitimate communicating parties receive multipath signals and estimate the multipath channel between the two communicating parties through the received signals. The multipath channel estimation parameters can be obtained using the least squares method. The process is expressed as:

[0049] in, represents the multipath channel estimation between the communicating 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, and g AB represents the channel gain between the communicating parties Alice and Bob, and n represents the noise component.

[0050] Specifically, Figure 3As shown, the embodiment of the present invention combines the above-mentioned least squares method to provide a method and technical route for realizing multipath channel estimation using a single intelligent information metamaterial antenna, assuming that the wireless channel is quasi-static block fading, and the channel remains unchanged during the entire channel estimation and subsequent data transmission. The pilot sequence used for channel estimation consists of K pilot signals. In each pilot signal, the directional pattern of the information metamaterial antenna changes agilely M times, so the receiver can obtain K×M sampling values, and use these sampling values ​​to complete the entire channel estimation process. Within the duration of k pilot symbols, the information metamaterial antenna quickly changes the metamaterial antenna state m times, then

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

[0052] Among them, y km represents the signal received by the information metamaterial antenna at the mth fast change when sending the kth pilot symbol, ω m represents the beamforming coefficient, A(θ) represents the direction vector, and h BR (θ) represents the multipath channel coefficient, represents the pilot sequence sent by Bob, n km Indicates receiving noise.

[0053] Arrange the M received multipath signals to generate a column vector y k ,Right now

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

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

[0056] s k It is a known signal, so using LS, MMSE, LMMSE and other channel estimation algorithms, we can get h BA Taking the LS algorithm as an example, the channel estimation result can be obtained by the following formula:

[0057]

[0058] Among them, Y M×K =[y1,…,y K ],s=[s1,…,s K ] T Represents the pilot sequence.

[0059] In order to be able to Medium recovery BR , let F(θ)=Ω T A(θ), then

[0060]

[0061] in, represents the residual noise, F(θ) is a function of θ, and solving the above equation can realize h BR The estimate of

[0062]

[0063] For information metamaterial antennas, multipath may come from any direction on the opposite side of the array, that is, θ l ∈[-π / 2,π / 2], sample [-π / 2,π / 2] at intervals of △θ=π / P, and get the sequence Denote as the assumed direction. When the value of P is large enough, the true direction parameter θ l With the assumed direction parameter Very close, it can be estimated Instead of estimating h BR (θ). At this time, the problem to be solved becomes:

[0064]

[0065] In order to make the estimation result accurate enough, an iterative algorithm is designed to solve the above equations to obtain the best channel estimation performance.

[0066] Step 2: The legitimate communicating parties form a transmission pattern and a reception pattern based on the multipath channel parameters, scramble the phase of the multipath channel based on the transmission pattern and the reception pattern, and convert the multipath channel into a composite channel;

[0067] Specifically, the two parties in legitimate communication form directional diagrams that are simultaneously aligned with the multipath spatial directions, namely, the sending directional diagram and the receiving directional diagram, and scramble the phases of the multipath channels in different directions, and the scrambled phases of the multipath channels in different directions are independent and random.

[0068] On the basis of accurately identifying the multipath channel, the transmitter and receiver add different phase perturbations to the multipaths in different directions to randomize the phase of each multipath channel. The phase perturbations of Alice and Bob are represented as △θ and Then the array element pattern after adding disturbance can be expressed as:

[0069]

[0070] where ψ n (α1),φ m (β1) are the array element directional coefficients of Alice and Bob before adding disturbance, ψ n and φ m Represents the directional pattern after adding perturbations.

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

[0072] It can be understood that in order to maximize the channel entropy, Alice and Bob should ensure that the channel parameters are independent at each channel estimation, so phase scrambling should be performed in conjunction with the communication process with Alice and Bob. In this mode, the uplink and downlink channels at each communication are still reciprocal, and the multipath channel phases at each estimation are independent of each other, so the phase of the multipath channel can be used as a random source to obtain a larger key capacity than the slowly varying channel.

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

[0074] Specifically, under the condition that the multipath phase scrambling weights are guaranteed to remain unchanged, the two legal communicating parties send pilot sequences to each other, re-estimate the multipath channel, and obtain the phase of the composite channel.

[0075] Specifically, Alice and Bob send pilot detection signals to each other. Alice sends detection signal SA to Bob at a certain moment. After time t1, Bob successfully receives detection signal YB. Then Bob experiences a transmit-receive conversion time Δt, while Alice experiences a transmit-receive conversion time Δt. Then Bob sends detection signal SB to Alice. After time t2, Alice receives detection signal YA, thus completing a two-way channel detection. Assuming that the channel coherence time is Tc, in order to ensure that both parties obtain highly correlated detection values, a detection cycle must be completed within the coherence time, that is: t1+t2+Δt≤Tc.

[0076] Step 4: The two legitimate communicating parties use the phase of the composite channel as the key source, perform sampling and quantization in the same way, and generate a key sequence.

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

[0078] Step 5: The legitimate communicating parties negotiate information on the key sequence, remove or correct inconsistent bits in the keys generated by the legitimate communicating parties, and obtain a consistent key sequence.

[0079] Specifically, inconsistent keys caused by channel estimation errors are corrected through information negotiation methods based on error correction codes such as BCH coding, convolutional coding, LDPC coding, and Polar coding. Cascade or Winnow algorithms may also be used, and the specific quantization method is determined according to the inconsistency rate of the key sequence.

[0080] Step 6: The legitimate communicating parties use the same privacy amplification algorithm to process the consistent key sequence to obtain the final key sequence.

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

[0082] Furthermore, based on the method proposed in the above embodiment, 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.

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

[0084] Correspondingly, in step 4, the two legal communicating parties respectively use other channel parameters of the composite channel to generate keys.

[0085] In the above embodiment, both parties of the legitimate communication are equipped with array antennas or single antennas of intelligent information metamaterials, and have the ability to separate wireless multipath channels. It should be noted that the legitimate communication party is equipped with multiple antennas or single antennas of intelligent information metamaterials, and has the ability to separate wireless multipath channels. The method of the above embodiment is used to perform multipath channel phase scrambling on the legitimate communication party, which can also improve the key generation rate and also belongs to the scope of the technical solution of this embodiment.

[0086] The method proposed in the embodiment of the present invention utilizes the multipath channel phase, an "intrinsic security resource" that naturally exists in the communication process and has not been fully exploited, to randomly scramble the anisotropic multipath channel phase, and uses the scrambled composite channel phase information to generate a key. This not only improves the key capacity and the randomness of the key source, but also ensures that the receiving signal-to-noise ratio of the communicating parties remains unchanged, thereby enhancing the channel entropy without affecting the communication performance.

[0087] Furthermore, in step 1, the arrival angle estimation value can be used as a multipath channel parameter, and estimating the arrival angle estimation value 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 arrival angle in the angle value space, and selecting the angles corresponding to the largest L peaks as the arrival angle estimation value, where L is the number of multipath channel paths between the communicating parties.

[0088] Furthermore, in step 2, the legal communicating parties form a transmission pattern and a reception pattern based on the multipath channel parameters, including: designing beamforming coefficients based on the arrival angle estimation value and using the linear constrained minimum variance criterion, and forming a transmission pattern and a 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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: The two legitimate communication parties send pilot sequences to each other and receive multipath signals; and estimating multipath channel parameters according to the multipath signal to obtain the phase of the multipath channel; Step 2: The legitimate communicating parties form a transmission directional diagram and a reception directional diagram based on the multipath channel parameters, scramble the phase of the multipath channel based on the transmission directional diagram and the reception directional diagram, and convert the multipath channel into a composite channel; Step 3: The legitimate communicating parties send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel; Step 4: The two legitimate communicating parties respectively use the phase of the composite channel as a key source, perform sampling and quantization in the same manner, and generate a key sequence; Step 5: The legitimate communicating parties negotiate information on the key sequence, remove or correct inconsistent bits in the keys generated by the legitimate communicating parties, and obtain a consistent key sequence; Step 6: The legitimate communicating parties use the same privacy amplification algorithm to process the consistent key sequence to obtain the final key sequence.

2. A 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. A wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that: In step 1, the arrival angle estimation value is used as the multipath channel parameter, and estimating the arrival angle estimation value 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 arrival angle in the angle value space, and selecting the angle corresponding to the largest L peaks as the arrival angle estimation value, where L is the number of multipath channel paths between the communicating parties.

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

5. The method for generating a wireless key based on multipath channel phase random scrambling according to claim 1, characterized in that: In step 1, the method and technical route for realizing multipath channel estimation using a single antenna of an intelligent information metamaterial specifically include: 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 represents the signal received by the information metamaterial antenna at the mth fast change when sending the kth pilot symbol, nkm represents the received noise, ω m represents the beamforming coefficient, h BR (θ) represents the multipath channel coefficient, s k 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, 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 Denotes the pilot sequence, and F(θ)=Ω T A(θ), then in, represents the residual noise, and solving the following equation yields h BR Estimates:

6. A 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 the multipath channels in different directions converts the multipath channels into composite channels, specifically including: the legitimate communication parties add different phase perturbations to the multipaths in different directions, and the array element directional pattern ψ after the perturbation is added n and φ m It can be expressed as: Among them, ψ n (α i ),φ m (β i ) are the array element directional coefficients of the two legal communicating parties before adding disturbances, △θ and They respectively represent the phase disturbances added by the legitimate communicating parties.

7. A wireless key generation method based on multipath channel phase random scrambling according to claim 1, characterized in that: In step 3, the legal communicating parties send pilot sequences to each other, estimate the composite channel, and obtain the phase of the composite channel, which also includes: obtaining parameters related to the phase.

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

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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