CN-116866907-B - Physical layer key generation and distribution method based on WFRFT subcarrier index

CN116866907BCN 116866907 BCN116866907 BCN 116866907BCN-116866907-B

Abstract

A physical layer key generation and distribution method based on WFRFT subcarrier index belongs to the field of physical layer secure communication. The invention solves the problem that the key of the traditional key generation and distribution method based on the subcarrier index is easy to be deciphered. The invention improves the concealment of the subcarrier activation state by utilizing the WFRFT communication system, changes the energy distribution of the WFRFT system on a time-frequency plane by adjusting the transformation parameters of the WFRFT, ensures the uniform distribution of the time-frequency plane energy of the WFRFT system by energy redistribution, ensures that signals show the characteristic of Gaussian, further obtains a more concealed subcarrier energy distribution mode, and can effectively solve the defect that the key generation and distribution method of the traditional subcarrier index is easy to be deciphered. Meanwhile, compared with the traditional OFDM system, the WFRFT system has better channel distortion resistance, and can improve the key authentication success rate on the premise of not sacrificing the key rate. The method can be applied to the field of physical layer safety communication.

Inventors

YIN XINYU
FANG XIAOJIE
LIU LIZHE
LI YONG
WANG BIN
SHA XUEJUN

Assignees

哈尔滨工业大学
中国电子科技集团公司第五十四研究所

Dates

Publication Date: 20260505
Application Date: 20230823

Claims (10)

1. The physical layer key generation and distribution method based on WFRFT subcarrier index is characterized by comprising the following steps: Step one, an i legal receiving end Bob i sends a pilot sequence to a legal transmitting end through an uplink channel, i=1, 2, & gt, N B ,N B represents the total number of legal receiving ends, the pilot sequence sent by each legal receiving end is x= [ x 1 ,x 2 ,…,x N ], and N is the length of the pilot sequence x; The legal transmitting terminal receives the frequency domain signal of the ith legal receiving terminal as Y s,i (f i ,t i ), and estimates the channel response according to Y s,i (f i ,t i ) Representing complex number set, f i is the frequency of the ith legal receiving end, t i is the uplink time slot of the ith legal receiving end; Step two, according to Generating WFRFT order alpha i and session key of ith legal receiving end According to Generating a group key sequence k G ; Step three, for the ith legal receiving end Bob i , the session key of the ith legal receiving end Bob i is utilized Encrypting the group key sequence k G to obtain an encrypted group key sequence k Gi ; The legal transmitting end transmits a group key sequence k Gi to the legal receiving end Bob i , wherein the length of the group key sequence k Gi is k i bits, and the group key sequence k comprises an index sequence c i,1 with the length of k i,1 bits and a modulation sequence c i,2 with the length of k i,2 bits, namely k i,1 +k i,2 ＝k i ; Step four, the ith legal receiving end Bob i occupies M subcarriers for distributing the group key sequence K Gi , the M subcarriers are divided into G subcarriers, each subcarrier contains P subcarriers, p=m/G, the index sequence c i,1 in the group key sequence K Gi is mapped to the subcarriers of each subcarrier, namely, K subcarriers in P subcarriers are activated for each subcarrier; modulating a modulation sequence c i,2 in a group key sequence k Gi , mapping the modulated symbols onto activated subcarriers, and obtaining a data block D i with the length of Mx 1 after mapping; fifthly, after zero padding is carried out on the data block D i , an extended data block S i ＝[0 M(i-1) ;D i ;0 N-Mi with the length of N multiplied by 1 is obtained, wherein the subscript of 0 represents the length of a zero vector; WFRFT with the order of alpha i is carried out on the data block S i , and a WFRFT result corresponding to the ith legal receiving end Bob i is obtained; step six, executing the processes from the step three to the step five for each legal receiving end; Combining the WFRFT results corresponding to the legal receiving ends, and performing WFRFT with the order of beta on the combined results to obtain a key signal y; Seventhly, carrying out equalization operation on the key signal y by the ith legal receiving end Bob i to obtain an equalized sequence u, and then processing the equalized sequence u to extract sequence information belonging to the ith legal receiving end Bob i Eighth, the ith legal receiving end Bob i pairs of sequence information Carrying out subcarrier index detection to obtain a detection result of a subcarrier activation state, and restoring an index sequence c i,1 according to the detection result of the subcarrier activation state; According to Demodulating the subcarrier activation state detection result, recovering a modulation sequence c i,2 , recovering an index sequence and the modulation sequence to obtain a group key sequence k Gi ; Step nine, the ith legal receiving end Bob i restores the session key according to the channel estimation result And step ten, respectively executing the processes from the step seven to the step nine on each legal receiving end, and restoring the session key and the group key sequence of each legal receiving end.
2. The physical layer key generation and distribution method based on WFRFT subcarrier index according to claim 1, wherein the channel response is characterized in that The method comprises the following steps: wherein P i (f i ) is the frequency domain sequence of pilot sequence x.
3. The physical layer key generating and distributing method based on WFRFT subcarrier index according to claim 2, wherein the following is the following Generating WFRFT order alpha i and session key of ith legal receiving end The specific process of (2) is as follows: Wherein alpha i is WFRFT order of the ith legal receiving end, For the session key of the ith legal receiving end, G i and K i are predefined signature sequences for key generation enhancement, and F d (·) and F k (·) represent physical layer key generation manners.
4. The physical layer key generating and distributing method based on WFRFT subcarrier index as set forth in claim 3, wherein said step of generating and distributing is based on The specific process of generating the group key sequence k G is as follows: Where k G is the group key sequence, Representing an exclusive or operation.
5. The physical layer key generating and distributing method based on WFRFT subcarrier index as claimed in claim 1, wherein said N B legal receiving ends send pilot sequences to legal transmitting ends in different time slots according to a defined order.
6. The method for generating and distributing physical layer keys based on WFRFT subcarrier indexes as claimed in claim 4, wherein said modulating sequence c i,2 in the group key sequence k Gi is Q-order QAM or PSK.
7. The physical layer key generation and distribution method based on WFRFT subcarrier index of claim 6, wherein the steps of Represents the number of combinations and the number of combinations, Represents a rounding down, k i,2 ≤Klog 2 Q.
8. The physical layer key generating and distributing method based on WFRFT subcarrier index according to claim 7, wherein the key signal y is: Where H represents the time domain channel matrix, Representing a WFRFT operation of order beta and length N, Representing WFRFT operation of order α i , length N, N being channel noise.
9. The physical layer key generating and distributing method based on WFRFT subcarrier index according to claim 8, wherein the sequence information The method comprises the following steps: Wherein C i represents the M (i-1) +1 th to Mi th elements extracted from the equalized sequence u, Representing an inverted WFRFT operation of order-beta and length N, Representing an inverse WFRFT operation of order- α i , length M.
10. The physical layer key generating and distributing method based on WFRFT subcarrier index of claim 9, wherein the specific process of step nine is as follows: step nine one, at time slot Legal transmitting end broadcasts preset pilot sequence to ith legal receiving end Bob i The i legal receiving terminal Bob i performs channel estimation according to the received signal Wherein, the Is the frequency domain received signal received by the ith legal receiving end Bob i , P alice (f i ) is the frequency domain sequence of the pilot sequence x', The channel estimation result is the channel estimation result of the i legal receiving end Bob i ; Step nine, the ith legal receiving end Bob i restores the session key according to the channel estimation result

Description

Physical layer key generation and distribution method based on WFRFT subcarrier index Technical Field The invention belongs to the field of physical layer secure communication, and particularly relates to a key generation and distribution method based on WFRFT (Weighted FractionalFourierTransform ) subcarrier index. Background With the wide popularization of the internet of things, wireless applications are becoming more diversified and distributed, and the trend is to make the demands on communication security more urgent so as to cope with security threats such as resistant eavesdropping. In the face of heterogeneous and ubiquitous internet of things networks, key distribution and management face great difficulty and vulnerability, traditional information confidentiality is usually achieved by means of an upper encryption technology, and due to the fact that computing resources of the bottom layer of internet of things hardware equipment are limited, a great challenge is faced by adopting a traditional encryption algorithm or variety, and a traditional encryption key exchange protocol is easily attacked by an adversary, so that safety risks are brought. Therefore, how to implement secret key sharing mechanisms efficiently and with low complexity is an urgent issue. In recent years, physical layer key generation methods are gradually attracting attention in academia and industry, and unlike encryption key generation schemes which rely on computational complexity to realize security, physical layer key generation methods utilize inherent randomness of wireless channels to realize establishment of secret keys, have the advantages of low cost and real-time updating, and are very suitable for application of the internet of things with limited resources. The existing key generation and distribution method based on subcarrier indexes is realized based on OFDM (Orthogonal Fourier Divison Multiplexing) system, under the signal system, an illegal eavesdropping terminal can easily monitor the subcarrier activation state by observing subcarrier energy in a frequency domain, so that the key is deciphered, and security threat is caused. Therefore, a more hidden and safe physical layer key generation and distribution method is needed, so as to protect the activation state of the sub-carrier from being decrypted and ensure the key security. Disclosure of Invention The invention aims to solve the problem that a key of a traditional key generation and distribution method based on subcarrier indexes is easy to decipher, and provides a physical layer key generation and distribution method based on WFRFT subcarrier indexes. The technical scheme adopted by the invention for solving the technical problems is as follows: a physical layer key generation and distribution method based on WFRFT subcarrier index specifically comprises the following steps: Step one, an i legal receiving end Bob i sends a pilot sequence to a legal transmitting end through an uplink channel, i=1, 2, & gt, N B,NB represents the total number of legal receiving ends, the pilot sequence sent by each legal receiving end is x= [ x 1,x2,…,xN ], and N is the length of the pilot sequence x; The legal transmitting terminal receives the frequency domain signal of the ith legal receiving terminal as Y s,i(fi,ti), and estimates the channel response according to Y s,i(fi,ti) Representing complex number set, f i is the frequency of the ith legal receiving end, t i is the uplink time slot of the ith legal receiving end; Step two, according to Generating WFRFT order alpha i and session key of ith legal receiving endAccording toGenerating a group key sequence k G; Step three, for the ith legal receiving end Bob i, the session key of the ith legal receiving end Bob i is utilized Encrypting the group key sequence k G to obtain an encrypted group key sequence k Gi; The legal transmitting end transmits a group key sequence k Gi to the legal receiving end Bob i, wherein the length of the group key sequence k Gi is k i bits, and the group key sequence k comprises an index sequence c i,1 with the length of k i,1 bits and a modulation sequence c i,2 with the length of k i,2 bits, namely k i,1+ki,2＝ki; Step four, the ith legal receiving end Bob i occupies M subcarriers for distributing the group key sequence K Gi, the M subcarriers are divided into G subcarriers, each subcarrier contains P subcarriers, p=m/G, the index sequence c i,1 in the group key sequence K Gi is mapped to the subcarriers of each subcarrier, namely, K subcarriers in P subcarriers are activated for each subcarrier; modulating a modulation sequence c i,2 in a group key sequence k Gi, mapping the modulated symbols onto activated subcarriers, and obtaining a data block D i with the length of Mx 1 after mapping; fifthly, after zero padding is carried out on the data block D i, an extended data block S i＝[0M(i-1);Di;0N-Mi with the length of N multiplied by 1 is obtained, wherein the subscript of 0 represents the le