CN114040392A - Uniform quantization method based on median non-uniform normalization and applicable to uncoordinated wireless channel key generation system - Google Patents

Abstract

The invention discloses a uniform quantization method based on the non-uniform normalization of median, which can be applied to an uncoordinated wireless channel key generation system. First, the two communicating parties transmit pilot signals to each other, and channel measurement to obtain wireless channel characteristic information. ; Second, divide the wireless channel feature information into two intervals with the median as the boundary, and perform non-uniform normalization of different scales on the data sets in the two intervals; then, integrate the non-uniformly normalized data sets. Then the whole is uniformly quantized; finally, the quantized bit sequence is bit-mapped with the corresponding Gray code, and then interleaved through a random matrix to obtain the final key bit stream. Through the method of the present invention, the randomness of the asymmetric private keys of the two communication parties can be improved and the inconsistency rate can be reduced, thereby reducing the bit error rate of channel error correction decoding in the uncoordinated wireless channel key generation technology, and finally achieving better performance. Secure message transmission for shared wireless channel characteristics.

Description

A Uniform Quantization Method Based on Median Non-Uniform Normalization Applicable to Uncoordinated Wireless Channel Key Generation System

technical field

The invention relates to the technical field of information security, in particular to a uniform quantization method based on non-uniform normalization of medians, which can be applied to an uncoordinated wireless channel key generation system.

Background technique

The physical layer security technology based on the characteristics of the wireless channel mainly uses the physical layer characteristics of the wireless channel to quantify the key bit stream, and then the two communicating parties generate a consistent shared key through information reconciliation and privacy amplification and provide it to the upper encryption system, thereby ensuring the communication system. safety.

By using the channel error correction coding technology, it is possible to avoid leaking the secret wireless channel feature information of both parties during the information reconciliation process, and reduce the high complexity of key acquisition due to privacy amplification.

In the existing research on the wireless key generation system based on channel error correction coding, most of the quantization methods use uniform quantization or sequence quantization, which leads to a high key inconsistency rate of the initial keys of both parties, and channel error correction decoding errors. higher rate. Therefore, a new quantization method with higher randomness and lower key inconsistency rate is required.

SUMMARY OF THE INVENTION

Purpose of the invention: Aiming at the high key inconsistency rate of the initial key obtained by using the existing quantization method for wireless channel characteristics in the wireless key generation system based on channel error correction coding, the present invention proposes a method that can be applied to non-coordination. Uniform quantization method based on median non-uniform normalization for wireless channel key generation system. The method divides the data set into two intervals by the median amplitude of the wireless channel characteristics, and performs non-uniform normalization of different scales respectively. Then, after merging the data sets, the whole data set is uniformly quantized, and finally the gray code of the corresponding order is used. It is mapped into a key bit stream, and after interleaving, an initial key with high randomness and low key agreement rate is obtained, which improves the subsequent channel error correction coding and decoding performance.

Technical solution: A uniform quantization method based on median non-uniform normalization that can be applied to an uncoordinated wireless channel key generation system of the present invention includes the following steps:

(1) Both parties of the communication (party A and party B) use the time division duplex mode to transmit pilot sequences to each other, measure the channel characteristics of the channels of the communication parties to the other party, and obtain their corresponding wireless channel characteristic information;

(2) Divide the wireless channel characteristic information data set into two intervals according to the median, respectively perform non-uniform normalization of different scales, and then combine to obtain the wireless channel characteristic information data set with the same scale as the initial scale;

(3) uniformly quantizing the wireless channel characteristic information data set obtained by non-uniform normalization;

(4) The initial key bit stream is obtained by Gray mapping of the uniformly quantized wireless channel feature information data set;

(5) Use random matrix to interleave the initial key bit stream to obtain the asymmetric private keys of both parties;

(6) Party A of the communication performs channel error correction coding after preprocessing the information to be transmitted to generate a bit sequence after channel error correction coding;

(7) Party A of the communication encodes the bit sequence of the channel error correction code generated in step (6) and the private key obtained in step (5) to obtain an encrypted data stream, and then sends it to the communication through the public channel Party B;

(8) Party B of the communication uses the private key obtained in step (5) to decode the received data stream to obtain an initial decryption bit sequence, and then performs channel error correction decoding on the initial decryption bit sequence to obtain a decoded bit sequence;

(9) Party B of the communication obtains decryption information by subjecting the decoded bit sequence obtained in step (8) to the inverse preprocessing process of step (5).

Further, the pilot sequence in step (1) should be a time-domain symbol sequence in a single-carrier transmission system, or a frequency-domain subcarrier pilot sequence in a multi-carrier transmission system, and the channel characteristics should be the measured channel time. Domain impulse response characteristics, or the measured channel frequency domain amplitude response characteristics.

Further, step (2) specifically includes:

(2-1) Use the median to divide the channel state information data set CSI into interval A: [0, Median(CSI)) and interval B: [Median(CSI), Max(CSI)];

where Median(CSI) and Max(CSI) are the median and maximum value of CSI in the dataset, respectively.

(2-2) Take the maximum value and minimum value of each interval for interval A and interval B and perform uniform normalization. The data in interval A is normalized to the interval [0,2 ^L-1 ), and the data in interval B is normalized to the interval [0,2 L-1 ]. Normalize to the [2 ^L-1 , 2 ^L ) interval, and then combine the data of these two intervals as the non-uniform normalized data set Normal of the original data set, which is normalized to the range of [left, right] The normalization formula is as follows:

Normal(i)=Round(left+k*(CSI(i)-Min(CSI)))

Round(.)为四舍五入，Max(.)和Min(.)分别为取最大值和最小值，L为大于1的整数。in,

Round(.) is rounding, Max(.) and Min(.) are the maximum and minimum values, respectively, and L is an integer greater than 1.

Further, step (3) specifically includes:

Perform the following uniform quantization on the non-uniform normalized data set Normal to obtain the uniform quantized data set Quantify:

Among them, L is an integer greater than 1, and R is the quantization order.

Further, step (4) specifically includes:

The uniform quantization data set Quantify is converted from decimal to binary, and then the binary code is converted into the corresponding R-bit Gray code, and the initial key bit stream is obtained after splicing.

Further, step (5) specifically includes:

Through the random interleaving matrix shared by the two communication parties, the burst errors in a string are scrambled into intermittent random errors, which is beneficial to improve the subsequent channel error correction coding performance.

Further, step (6) specifically includes:

The communication party A encrypts the transmitted information using the information encryption processing method shared by both parties, and then performs channel error correction coding to generate a bit sequence after channel error correction coding.

Further, step (7) specifically includes:

A bit-by-bit XOR operation is performed on the private key obtained by the communication party A in step (5) and the bit sequence after channel error correction coding generated by the communication party A in step (6).

Further, step (8) specifically includes:

A bit-by-bit XOR operation is performed between the private key obtained by the communication party B in step (5) and the bit sequence transmitted by the communication party A through the public channel in step (7).

Further, step (9) specifically includes:

The communication party B uses the information decryption processing method shared by both communication parties to decrypt the received information to obtain the final decrypted information.

Beneficial effects:

Compared with the prior art, the present invention has the significant advantage that: the present invention divides the interval according to the median, and then performs non-uniform normalization of each interval, so that interval features are more refined and averaged. Then, the initial key bit stream is obtained by uniform quantization, and then the randomness is improved by Gray mapping, and the interleaving reduces the string of bit errors. In the test process, in the face of channel conditions in different environments, there is a low key inconsistency rate, which can effectively reduce the bit error rate of channel coding and decoding, and has good practicability.

Description of drawings

Fig. 1 is the system flow chart of the present invention;

Fig. 2 is the characteristic diagram of the frequency domain subcarrier amplitude channel obtained based on the wireless channel of the present invention;

Fig. 3 is the channel non-uniform normalization result diagram that the present invention obtains based on wireless channel characteristic;

Fig. 4 is the channel uniform quantization result graph obtained based on the wireless channel non-uniform normalization result of the present invention;

5 is a key bitmap obtained by performing Gray mapping based on the uniform quantization result of the wireless channel according to the present invention;

6 is a comparison diagram of the key inconsistency rate under multiple quantization methods of the present invention;

FIG. 7 is the bit error rate under each quantization order based on Polar channel coding and decoding according to the present invention.

Detailed ways

As shown in FIG. 1, this embodiment provides a uniform quantization method based on median non-uniform normalization that can be applied to an uncoordinated wireless channel key generation system, which specifically includes the following steps:

S1. In a better indoor or outdoor environment, the two communicating parties (Alice and Bob) transmit pilot sequences to each other in a time-division duplex mode, measure the channel characteristics of the communication parties to each other's channels, and obtain their corresponding wireless channel feature information;

Based on the USRP N210 software radio platform, Alice and Bob measure channel characteristics by sending pilot frequencies P to each other. In this embodiment, the amplitude characteristics of Alice and Bob in the frequency domain based on the wireless channel are considered.

The USRP device works at a sampling rate of 25MHz, collects a pilot signal with a baseband frequency of 2475MHz and a bandwidth of 20MHz, and the transmit gain and receive gain range from [0,30]dB.

Through channel detection, Alice and Bob obtain their respective channel features H, and the obtained wireless channel frequency domain features are shown in Figure 2 . As can be seen from Figure 2, due to various factors such as channel changes in the detected time slot, interference in the environment, and hardware fingerprints, the obtained wireless channel frequency domain characteristics will have certain differences.

S2, Alice and Bob respectively divide the measured channel feature data set into two intervals by the median of amplitude: A:[0,Median(CSI)) and interval B:[Median(CSI),Max(CSI) ];

where Median(CSI) and Max(CSI) are the median and maximum value of CSI in the dataset, respectively.

Take the maximum value and minimum value of each interval for interval A and interval B and perform uniform normalization. The data in interval A is normalized to the [0,2 ^L-1 ) interval, and the data in interval B is normalized to [2 ^L-1 , 2 ^L ) interval, and then combine the data of these two intervals as the non-uniform normalized data set Normal of the original data set, where the normalization formula normalized to the [left, right] range is as follows :

Normal(i)=Round(left+k*(CSI(i)-Min(CSI)))

Round(.)为四舍五入，Max(.)和Min(.)分别为取最大值和最小值，L为大于1的整数。in,

Round(.) is rounding, Max(.) and Min(.) are the maximum and minimum values, respectively, and L is an integer greater than 1.

The obtained channel non-uniform normalization result is shown in Figure 3.

S3. Use the non-uniform normalized data set Normal obtained in S2 to perform the following uniform quantization to obtain a uniform quantized data set Quantify:

Wherein, L is an integer greater than 1, and R is a quantization order. In this embodiment, it is considered that the quantization order is 3′.

The obtained channel non-uniform normalization results are shown in Figure 4.

The uniform quantization method is to uniformly normalize the entire channel feature data set, and then perform uniform quantization.

The sorting quantization method is to sort the amplitude of the channel feature data set from small to large, and then perform bit replacement between partitions according to the quantization order.

S4. The uniform quantization data set Quantify obtained by S3 is converted from decimal to binary, and then the binary code is converted into the corresponding R-bit Gray code, and the initial key bit stream is obtained after splicing.

The obtained channel non-uniform normalization results are shown in Figure 5. As can be seen from Figure 5, the 0/1 bit sequences in the private keys finally obtained by Alice and Bob have certain differences.

S5. Using the initial key bit stream obtained in S4, through random interleaving _matrix interleaving, both parties of legitimate communication obtain asymmetric private keys KA and _KB .

S6. Alice encrypts the information M to be sent by the information encryption processing method shared by both legal communication parties to obtain encrypted information M', and then Alice processes the encrypted information M' by selecting a channel error correction coding algorithm to obtain the encoded information CM.

S7. Alice performs a bit-by-bit XOR operation on the encoded information CM and the asymmetric private key KA, obtains the sequence _S to be transmitted, and transmits it to Bob through the public channel.

S8. Bob performs an XOR operation on the received sequence _S and the asymmetric private key KB to solve the information S', and then Bob decrypts the information S' through the channel error correction decoding algorithm to obtain the information M'.

S9. Bob decrypts the information M' by using the information decryption processing method shared by both legal communication parties to obtain the information M transmitted by Alice.

The method of the present invention, under the condition of the same wireless channel characteristics, compared with the uniform quantization method and the sequence quantization method, the obtained key inconsistency rates are compared as shown in FIG. 6 .

The method of the present invention, combined with Polar channel coding and decoding, compares the bit error rate under each quantization order as shown in FIG. 7 .

The above is only the preferred embodiment of the present invention, it should be pointed out: for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (10)

1. A uniform quantization method based on median nonuniform normalization applicable to a non-coordinated wireless channel key generation system comprises the following steps:

(1) two communication parties (A party and B party) adopt a time division duplex mode to mutually transmit pilot frequency sequences, and measure the channel characteristics of the channels from the two communication parties to the other communication party respectively to obtain the corresponding wireless channel characteristic information of the two communication parties respectively;

(2) dividing the wireless channel characteristic information data set into two intervals according to the median, respectively carrying out non-uniform normalization of different scales, and then combining to obtain a wireless channel characteristic information data set with the same initial scale;

(3) uniformly quantizing the wireless channel characteristic information data set obtained by non-uniform normalization;

(4) gray mapping is carried out on the wireless channel characteristic information data set obtained by uniform quantization to obtain an initial key bit stream;

(5) interleaving the initial key bit stream by using a random matrix to obtain asymmetric private keys of the two parties;

(6) the communication A party carries out channel error correction coding on information to be transmitted after preprocessing, and generates a bit sequence after the channel error correction coding;

(7) the party A of the communication performs coding operation on the bit sequence of the channel error correction coding generated in the step (6) and the private key obtained in the step (5) to obtain an encrypted data stream, and then sends the encrypted data stream to the party B of the communication through a public channel;

(8) the B party of communication uses the private key obtained in the step (5) to perform decoding operation on the received data stream to obtain an initial decryption bit sequence, and then performs channel error correction decoding on the initial decryption bit sequence to obtain a decoding bit sequence;

(9) and (5) the B party of communication obtains decryption information by carrying out the preprocessing process of the inverse step (5) on the decoding bit sequence obtained in the step (8).

2. The method of claim 1, wherein the method comprises the following steps: the pilot sequence in step (1) should be a time domain symbol sequence in a single carrier transmission system or a frequency domain subcarrier pilot sequence in a multicarrier transmission system, and the channel characteristic in step (1) should be a measured channel time domain impulse response characteristic or a measured channel frequency domain amplitude response characteristic.

3. The method of claim 1, wherein the method comprises the following steps: the non-uniform normalization in step (2) comprises the steps of:

(2-1) dividing the wireless channel characteristic information data set CSI into intervals A according to the median: [0, median (csi)) and interval B: [ median (CSI), max (CSI) ], where median (CSI), max (CSI) are the median and maximum of the CSI in the data set, respectively;

(2-2) uniformly normalizing the maximum value and the minimum value of the interval A and the interval B respectively, and normalizing the data of the interval A to [0, 2%^L-1) Interval, data for interval B normalized to [2^L-1，2^L) And combining the data of the two intervals to obtain a non-uniform normalized data set Normal of the original data set, wherein the normalized data set Normal is [ left, right ]]The normalization formula for the range is as follows:

Normal(i)＝Round(left+k*(CSI(i)-Min(CSI)))

wherein,

round (.) is rounded, Max (.) and Min (.) are taken as the maximum and minimum values, respectively, and L is an integer greater than 1.

4. The method of claim 1, wherein the method comprises the following steps: the uniform quantization in step (3) is specifically as follows:

and uniformly quantizing the non-uniform normalized data set Normal to obtain a uniformly quantized data set Quantify as follows:

wherein, L is an integer greater than 1, and R is a quantization order.

5. The method of claim 1, wherein the method comprises the following steps: and the gray mapping step in the step (4) comprises the steps of firstly converting the uniform quantization data set quantity from decimal into binary, then converting the binary code into corresponding R-bit gray code, and splicing to obtain the initial key bit stream.

6. The method of claim 1, wherein the method comprises the following steps: the random interleaving matrix in the step (5) is shared by both communication parties, and the burst errors are disorganized into discontinuous random errors, so that the subsequent channel error correction coding and decoding performance is improved.

7. The method of claim 1, wherein the method comprises the following steps: the preprocessing in the step (6) comprises the step of encrypting the information shared by the communication A party and the communication parties; and (4) performing channel error correction coding in the step (6), wherein the channel error correction coding comprises a BCH code, a Turbo code, an LDPC code and a Polar code, and the error correction capability is improved by adding redundant bits.

8. The method of claim 1, wherein the method comprises the following steps: and (5) performing bit-by-bit exclusive OR operation on the private key obtained by the communication party A in the step (5) and the bit sequence generated by the communication party A in the step (6) after channel error correction coding.

9. The method of claim 1, wherein the method comprises the following steps: and (3) the decoding operation in the step (8) comprises the step of carrying out bit-by-bit exclusive OR operation on the private key obtained by the communication party B in the step (5) and the bit sequence transmitted by the communication party A through the public channel in the step (7).

10. The method of claim 1, wherein the method comprises the following steps: the inverse preprocessing in the step (9) includes that the communication B party uses an information decryption processing method which is shared by both communication parties.

Images