A method for securely distributing quantum keys on the edge of the Internet of Things

Abstract

The present invention discloses a method for securely distributing quantum keys on the edge side of the Internet of Things. The communicating parties perform bidirectional detection and sampling of channel characteristics through pilot signal transmission, and then perform signal preprocessing; then, an improved differential value-based quantization method is used to convert the obtained channel measurement value into a binary bit sequence, thereby becoming a preliminary key material; then, based on the Cascade protocol, inconsistent bits in the preliminary key material between a pair of legally participating communicating parties are detected and corrected; a privacy amplification process is performed using a Hash function, and privacy amplification allows the communicating parties to extract a shorter but confidential key from the preliminary key; finally, the generated key is used to encrypt and transmit the quantum key, and the quantum key is securely distributed from the edge gateway to the Internet of Things terminal device. This method utilizes the reciprocity characteristics of electromagnetic wave propagation in the wireless channel, and uses the wireless channel as a natural random source for generating symmetric keys, thereby avoiding a complex key distribution process.

Description

Technical Field

[0001] The present invention belongs to the field of information security technology, discloses the application of wireless key generation technology in new fields, and specifically relates to a method for securely distributing quantum keys on the edge side of the Internet of Things. Background Art

[0002] The Internet of Things is one of the hottest technologies in the era of digital transformation. With the widespread application of the Internet of Things, its security and reliability issues have become the focus of attention. Many IoT terminals have limited storage and computing capabilities. Deploying security software or highly complex encryption and decryption algorithms on them will increase the operating burden and may even cause them to fail to operate normally. The mobility of some mobile terminals has caused security products that rely on network boundaries to fail to function normally. In order to improve the security of the Internet of Things, it is considered to apply quantum keys to secure communications in the Internet of Things.

[0003] Quantum secure communication is a new secure communication method that uses the basic principles of quantum mechanics and the "one-time one-pad" encryption system to achieve secure information transmission. It has the characteristics of super security and super high concealment. Quantum key distribution is a branch of quantum communication. It is an interdisciplinary subject that combines quantum mechanics and information theory in classical communication. Its main purpose is to use quantum technology to enable both parties in communication to obtain secure key information unconditionally without the information being stolen. The basic principles of quantum mechanics guarantee its theoretical unconditional security. Among them, the "quantum no-cloning theorem" and the "Heisenberg uncertainty principle" can realize the secure distribution and transmission of quantum keys. At present, quantum key distribution technology has become a hot topic in the field of key research.

[0004] At present, when distributing quantum keys to users on the edge of the Internet of Things, symmetric encryption schemes or asymmetric encryption schemes are generally adopted, but symmetric encryption schemes require an additional key distribution process, while asymmetric encryption schemes face the problem of high computational complexity. In addition, if an offline quantum key transfer mechanism is adopted, there are problems of poor security and poor practicality. Therefore, avoiding the complex symmetric key distribution process, reducing computational complexity, and ensuring the security and practicality of the method in the process of implementing quantum key distribution on the edge of the Internet of Things are urgent issues to be solved. Summary of the invention

[0005] The present invention is to achieve the safe and timely distribution of quantum keys on the edge of the Internet of Things to the Internet of Things terminals that are far away or have a high communication frequency in the Internet of Things, and provides a method for safely distributing quantum keys on the edge of the Internet of Things. The communicating parties perform bidirectional detection and sampling of channel characteristics through pilot signal transmission, and then perform signal preprocessing; then adopt an improved differential value-based quantization method to convert the obtained channel measurement value into a binary bit sequence, thereby becoming a preliminary key material; then based on the Cascade protocol, detect and correct inconsistent bits in the preliminary key material between a pair of legally participating parties in the communication; use the Hash function to perform a privacy amplification process, and allow the communicating parties to extract a shorter but confidential key from the preliminary key through privacy amplification; finally, use the generated key to encrypt and transmit the quantum key, and distribute the quantum key from the edge gateway to the Internet of Things terminal device securely. This method utilizes the reciprocity characteristics of electromagnetic wave propagation in the wireless channel, uses the wireless channel as a natural random source for generating symmetric keys, extracts the parameters of the reciprocal uplink and downlink channels from the received radio frequency signal, and converts them into symmetric keys for distributing quantum keys, so as to achieve one-time secure transmission.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: a method for securely distributing quantum keys on the edge side of the Internet of Things, comprising the following steps:

[0007] S1, channel detection and preprocessing: the communicating parties perform bidirectional detection and sampling of channel characteristics through pilot signal transmission, and then perform signal preprocessing, wherein the signal preprocessing at least includes advance calibration and application of transform domain algorithm;

[0008] S2, quantization: using an improved differential value-based quantization method, the channel measurement value obtained in step S1 is converted into a binary bit sequence, thereby becoming a preliminary key material;

[0009] S3, information coordination: Based on the Cascade protocol, detect and correct inconsistent bits in the preliminary key material between a pair of legitimate communicating parties;

[0010] S4, privacy amplification: using hash functions to perform privacy amplification, privacy amplification allows both parties to extract a shorter but confidential key from the preliminary key;

[0011] S5, quantum key distribution: Use the generated key to encrypt and transmit the quantum key, and securely distribute the quantum key from the edge gateway to the IoT terminal device.

[0012] As an improvement of the present invention, the step S1 further comprises:

[0013] S11, in the i thAt a sampling moment, the signal transmitter sends a request packet to the signal receiver, and the signal receiver obtains the CSI amplitude measurement value X B (i);

[0014] S12, after a time delay Δt, the signal receiver replies to the signal sender with a data packet, and the signal sender will also measure the same parameters and obtain the CSI amplitude measurement value X A (i);

[0015] S13, the communicating parties repeat steps S11 and S12 at regular intervals to avoid generating related samples, and finally obtain the original measurement result;

[0016] S14, calibrating the hardware in advance according to the measurement result obtained in step S13;

[0017] S15, processing the obtained CSI amplitude data by a 0-1 normalization method;

[0018] S16 uses a transform domain algorithm to obtain a pruned smaller time-frequency matrix through DCT transformation, removes redundancy in the time-frequency response, and suppresses noise.

[0019] As an improvement of the present invention, the step S2 further comprises:

[0020] S21: receiving the channel measurement value and performing average preprocessing on it, quantizing and averaging each CSI amplitude measurement value with the following 9 amplitude measurement values ​​to obtain a CSI amplitude waveform with high consistency that can be used for binary key sequence extraction;

[0021] S22: Check the CSI amplitude measurement value sequence obtained after quantization and averaging element by element. If the measurement value being checked is greater than both the previous and next measurement values ​​in the sequence, generate 2 bits: 11; if the measurement value being checked is greater than the previous measurement value in the sequence and less than the next measurement value, generate 2 bits: 10; if the measurement value being checked is less than the previous measurement value in the sequence and greater than the next measurement value, generate 2 bits: 01; if the measurement value being checked is less than both the previous and next measurement values ​​in the sequence, generate 2 bits: 00; if the measurement value being checked is equal to the previous or next measurement value, no bit is generated, and the position where the equal value appears is recorded in the auxiliary array. When the communication parties have inconsistent key lengths, they exchange auxiliary arrays on the channel, and each party deletes the 2 bits generated by itself when the other party is equal;

[0022] S23, splicing the bit sequence generated bit by bit in S22 in order, that is, preliminarily determining it as the quantized generated key.

[0023] As an improvement of the present invention, step S3 further includes:

[0024] S31, both communication parties perform a randomly agreed permutation on their respective bit strings so that the error bits in the permuted bit strings are as evenly distributed as possible;

[0025] S32, divide the permuted bit string into small segments with a fixed length, and then perform error correction on each small segment, where the number of error bits in each small segment is less than or equal to 1;

[0026] S33, both parties exchange the check sums of the corresponding small segments. For the small segments with different check sums, both parties use the binary search method for error correction, and no bits are deleted at this time;

[0027] S34, detect new errors through the errors initially detected after block division and the previous block division situation;

[0028] S35, repeat steps S31 - S34 until there are no error bits.

[0029] As another improvement of the present invention, step S4 further includes:

[0030] S41, select three cryptographic hash functions SHA - 3, SM3, and BLAKE as alternative hash functions;

[0031] S42, both parties negotiate and select the same hash function;

[0032] S43, input the key agreed upon by both parties into the Hash function, reduce the final key size from n bits to r (r < n) bits to eliminate the leaked information on the common channel, and convert the key agreed upon by both parties into a completely secure key.

[0033] Compared with the prior art: The present invention proposes a method for securely distributing quantum keys on the edge side of the Internet of Things. Utilizing the reciprocity feature of the electromagnetic wave propagation in the wireless channel, the wireless channel is used as a natural random source for generating symmetric keys. The parameters of the reciprocal uplink and downlink channels are extracted from the received radio frequency signals and converted into symmetric keys for distributing quantum keys, realizing one - time - one - key secure transmission and avoiding complex key distribution processes. In addition, after collecting the channel state information, this method eliminates large - scale fading to obtain a smaller - scale fading coefficient with stronger randomness. In the subsequent quantization process, considering the problems such as large computational complexity and reduced randomness caused by continuous Gray - code blocks in the currently common quantization method based on the cumulative distribution function, this method adopts a quantization method based on difference values in quantization, and improves on the existing algorithms to solve the problems existing in the quantization method based on the cumulative distribution function. Description of the Drawings

[0034] Figure 1This is a flowchart of the steps of a method for securely distributing quantum keys at the edge of the Internet of Things of the present invention;

[0035] Figure 2 This is a timing diagram of channel sampling in step S1 of the method of the present invention;

[0036] Figure 3 This is a flow chart of the quantification step in step S2 of the method of the present invention;

[0037] Figure 4 This is a flow chart of the information coordination step in step S3 of the method of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0039] Example 1

[0040] The symbols and their definitions in this embodiment are shown in Table 1 below:

[0041] Table 1

[0042]

[0043] like Figure 1 As shown, a method for securely distributing quantum keys on the edge side of the Internet of Things mainly includes the following steps:

[0044] Step S1, channel detection and preprocessing: the communicating parties perform bidirectional detection and sampling of channel characteristics through pilot signal transmission, and then perform signal preprocessing, wherein the signal preprocessing at least includes pre-calibration and application of transform domain algorithm;

[0045] The user samples the channel through data packet transmission. The channel sampling timing process based on the time division duplex (TDD) system is as follows: Figure 2 As shown, in this embodiment, the communication sender is denoted as Alice and the communication receiver is denoted as Bob. th At a sampling time, Alice sends a request packet to Bob, and then Bob can obtain the CSI amplitude measurement value X B (i). After a time delay Δt (Δt is much smaller than the coherence time T c ), Bob replies to Alice with a data packet, and Alice will also measure the same parameters and obtain the CSI amplitude measurement value X A (i) Since the same carrier frequency is used in both directions in the TDD scheme, unless strong frequency selective fading and different co-channel interference are encountered, the coherence time T cWithin a certain period of time, the complex channel envelope remains nearly constant. Therefore, Alice and Bob can obtain highly correlated measurement results. Alice and Bob will s Repeat the above sampling (T s >T c ) to avoid correlated sampling.

[0046] In the channel detection phase, Alice and Bob do not decrypt the received information, they just use these sampled pilots and common links to measure the channel. In addition, if additional packet transmission must be avoided, legitimate users can also rely on the payload packet method to sample the channel.

[0047] After the two communicating parties send pilot signals of the same strength, the signals received by both parties are highly correlated, but not exactly the same, because although the wireless channel is symmetrical, the measured values ​​of the wireless channel are not exactly the same. The difference in measured values ​​directly leads to the mismatch of the keys on Alice and Bob's end, and even the inability to generate secure bits. This is mainly due to two problems in the original channel, namely the loss of channel reciprocity and sampling autocorrelation. The loss of channel reciprocity is caused by hardware imbalance, fading, interference imbalance and channel noise. Hardware imbalance refers to the noise caused by the hardware of the receivers of the two communicating parties. Sampling autocorrelation means that when two detections are in the same coherence time or coherence bandwidth, there will be undesirable autocorrelation between adjacent measurements, which will cause redundancy.

[0048] In view of the two problems in channel measurement, the present invention can apply a signal preprocessing algorithm, the asymmetry of the hardware can be alleviated by early calibration, and the interference, noise and autocorrelation problems existing in channel measurement are solved by using a transform domain algorithm.

[0049] The signal preprocessing process specifically includes the following sub-steps:

[0050] First, the hardware fingerprint of the hardware is obtained through learning, and the noise is subtracted during detection.

[0051] Then, the measured CSI amplitude data is processed using a 0-1 normalization method.

[0052] Finally, the training sequence is sent repeatedly in a dense manner to measure the time-varying frequency response matrix, and then the matrix is ​​transformed into the "frequency domain" through DCT transformation. After retaining the low-frequency components with more energy, another DCT transformation is performed to obtain a trimmed smaller time-frequency matrix. The DCT transformation removes redundancy in the time-frequency response while also suppressing noise.

[0053] Step S2, quantization: using an improved differential value-based quantization method, the channel measurement value obtained in step S1 is converted into a binary bit sequence, thereby becoming a preliminary key material;

[0054] After the channel detection and preprocessing process is completed, follow Figure 3 The quantization step process shown uses a quantization algorithm to convert the original channel measurement value into a binary bit sequence that can be preliminarily determined as a key. This method uses an improved differential value-based quantization algorithm. Considering that the waveforms of the receiver and the sender are consistent in average sense, the received CSI waveform can be preprocessed: each CSI amplitude measurement value is quantized and averaged with the next 9 amplitude measurements. The resulting CSI amplitude waveform has a high degree of consistency, so that the key can be extracted. The specific algorithm pseudo code is shown below:

[0055]

[0056] The quantification step specifically includes:

[0057] S21,: Get channel measurement value X u (The measured value has been basically preprocessed to reduce the influence of noise, etc.), average preprocess it, use formula (x) to quantize and average each CSI amplitude measurement value with the following 9 measurement values, and obtain a CSI amplitude measurement value sequence Y with high consistency that can be used to extract the key u (i).

[0058]

[0059] S22: According to Y u (i), generate corresponding bit tuples element by element: if Y u (i)>Y u (i-1) and Y u (i)>Y u (i+1), generate 2 bits: 11; if Y u (i)>Y u (i-1) and Y u (i)<(i+1), generate 2 bits: 10; if Y u (i) <Y u (i-1) and Y u (i)>Y u (i+1), generate 2 bits: 01; if Y u (i)<(i-1) and Y u (i)<(i+1), generate 2 bits: 00; if it is within the precision range, Y u (i) = Y u (i-1) or Y u(i) = Y u (i+1), no bit is generated, and the position where the equality occurs is recorded in the auxiliary array. When the communicating parties generate inconsistent key lengths, the auxiliary arrays are exchanged on the channel, and each party deletes the 2 bits generated by the other party when the equality occurs.

[0060] S23: Sequentially concatenate the bit tuples generated in step S22 into a bit sequence, that is, obtain a bit string that is initially determined to be the key.

[0061] Step S3, information coordination: based on the Cascade protocol, detecting and correcting inconsistent bits in the preliminary key material between a pair of legally participating communication parties;

[0062] After the quantization process is completed, Figure 4 The specific process shown is to coordinate the bit strings obtained by the communicating parties to adjust the mismatched bits of the two parties to ensure that the two parties generate a pair of the same symmetric keys for cryptographic applications. The steps specifically include:

[0063] S31: The communicating parties agree on a random permutation method to rearrange the entire bit string to ensure that the erroneous bits appear at each position with a uniform probability.

[0064] S32: Both parties in communication select a suitable block size k i , in each round of error correction, the block size becomes twice as large as before, i.e., k i =2k i-1 . According to k i The bit strings of both parties are divided into blocks according to the size of K i .

[0065] S33: Binary error correction is performed on each divided block. The method of binary error correction is as follows. First, each block is divided into two small blocks in half. The two communicating parties exchange the checksum of the previous sub-block through a public channel. At the same time, both parties calculate the checksum in the same way. If the checksums are different, binary error correction is performed on the sub-block. If the checksums are the same, binary error correction is performed on the other sub-block until the position of the wrong bit is found. i .

[0066] S34: Based on the errors found in step S33, all blocks in the previous rounds can be divided into a set B. i Perform error correction again, i.e. i The block There must be another error that can be corrected. lThe set C composed of is corrected for binary errors in ascending order of block size. This process may increase or decrease the size of the set until the set is emptied, that is, the number of errors in all current blocks is even (possibly 0).

[0067] S35: Repeat the above process until there are no errors between the two bit strings. According to calculations, performing the above process 4 times can correct all the errors in the key less than 10 4 bits.

[0068] Step S4, privacy amplification: Use the Hash function for the privacy amplification process. Through privacy amplification, both communicating parties are allowed to extract a shorter but more secure key from the preliminary key;

[0069] After the information reconciliation process is completed, through privacy amplification, both communicating parties are allowed to extract a shorter but almost completely secure key from the common random variable. This method uses the Hash function for the privacy amplification process. The specific steps are as follows:

[0070] S51: Select three cryptographic hash functions, SHA-3, SM3, and BLAKE, as alternative hash functions.

[0071] S52: Suppose there is a random binary sequence q of length n i (here q i,a represents Alice's key, represents Bob's key). Suppose n is an integer (n needs to be an even number, and the key sequence needs to be bisected later). Divide q i into two sequences of equal length q i =q i,1 ‖q i,2 , each of length n / 2. Alice and Bob can negotiate the same hash function (for example, 0 corresponds to SHA-3, 1 corresponds to SM3) by calculating the equation , where p is the number of candidate hash functions. In this scheme, p = 3, and l = n / 2.

[0072] S53: Input the key agreed upon by both parties into the Hash function to reduce the final key size from n bits to r (r < n) bits to eliminate the leaked information on the public channel and convert the agreed-upon key into a completely secure key.

[0073] Step S5, distribute the quantum key: Use the generated key to encrypt and transmit the quantum key, and securely distribute the quantum key from the edge gateway to the IoT terminal device.

[0074] After all the above steps are completed, the communicating parties obtain the same symmetric key that can be used for cryptographic applications, and use this key to encrypt and transmit the quantum key, thereby achieving the secure distribution of the quantum key from the IoT edge gateway to the IoT terminal device.

[0075] This method uses a key generated based on the characteristics of the wireless channel to encrypt and transmit quantum keys on the edge side of the Internet of Things, to ensure that the quantum keys are securely distributed from the edge gateway to the Internet of Things terminal devices, thereby ensuring secure communication of the Internet of Things terminal devices. This method also uses the reciprocity characteristics of electromagnetic wave propagation in the wireless channel, uses the wireless channel as a natural random source for generating symmetric keys, extracts the parameters of the reciprocal uplink and downlink channels from the received radio frequency signal, and converts them into symmetric keys for distributing quantum keys, achieving one-time secure transmission while avoiding the complex key distribution process.

[0076] It should be noted that the above content merely illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A method for securely distributing quantum keys at the edge of the Internet of Things, characterized in that: The steps include: S1, channel detection and preprocessing: the communicating parties perform bidirectional detection and sampling of channel characteristics through pilot signal transmission, and then perform signal preprocessing, wherein the signal preprocessing at least includes advance calibration and application of transform domain algorithm; S11, in the i th At a sampling moment, the signal transmitter sends a request packet to the signal receiver, and the signal receiver obtains the CSI amplitude measurement value X B (i); S12, after a time delay Δt, the signal receiver replies to the signal sender with a data packet, and the signal sender will also measure the same parameters and obtain the CSI amplitude measurement value X A (i); S13, the communicating parties repeat steps S11 and S12 at regular intervals to finally obtain the original measurement result; S14, calibrating the hardware in advance according to the measurement result obtained in step S13; S15, processing the obtained CSI amplitude data by a 0-1 normalization method; S16, using the transform domain algorithm, through DCT transformation, obtains a trimmed smaller time-frequency matrix, removes redundancy in the time-frequency response, and suppresses noise; S2, quantization: using an improved differential value-based quantization method, the channel measurement value obtained in step S1 is converted into a binary bit sequence, thereby becoming a preliminary key material; S21: receiving the channel measurement value and performing average preprocessing on it, quantizing and averaging each CSI amplitude measurement value and the following 9 amplitude measurement values ​​to obtain a CSI amplitude waveform with high consistency that can be used for binary key sequence extraction; S22: Check the CSI amplitude measurement value sequence obtained after quantization and averaging element by element. If the measurement value being checked is greater than both the previous and next measurement values ​​in the sequence, generate 2 bits: 11; if the measurement value being checked is greater than the previous measurement value in the sequence and less than the next measurement value, generate 2 bits: 10; if the measurement value being checked is less than the previous measurement value in the sequence and greater than the next measurement value, generate 2 bits: 01; if the measurement value being checked is less than both the previous and next measurement values ​​in the sequence, generate 2 bits: 00; if the measurement value being checked is equal to the previous or next measurement value, no bit is generated, and the position where the equal value appears is recorded in the auxiliary array. When the communication parties have inconsistent key lengths, they exchange auxiliary arrays on the channel, and each party deletes the 2 bits generated by itself when the other party is equal; S23, splicing the bit sequence generated bit by bit in S22 in order, that is, preliminarily determining it as the quantized generated key; S3, information coordination: Based on the Cascade protocol, detect and correct inconsistent bits in the preliminary key material between a pair of legitimate communicating parties; S31, the communicating parties perform a random agreed permutation on their respective bit strings so that the error bits in the permuted bit strings are evenly distributed; S32, dividing the replaced bit string into small segments of fixed length, and then performing error correction on each small segment, wherein the number of error bits in each small segment is less than or equal to 1; S33, the two parties exchange the checksums of the corresponding small segments. For small segments with different checksums, the two parties use binary search to correct errors, and no bits are deleted at this time. S34, detecting new errors through the errors initially detected after the block division and the previous block division conditions; S35, repeating steps S31-S34 until there are no more erroneous bits; S4, privacy amplification: using hash functions to perform privacy amplification, privacy amplification allows both parties to extract a shorter but confidential key from the preliminary key; S41, Select three cryptographic hash functions SHA-3, SM3, and BLAKE as alternative hash functions; S42, The two parties negotiate to select the same hash function; S43, Input the key agreed upon by both parties into the Hash function, reduce the final key size from n bits to r bits to eliminate the leaked information on the common channel, where r < n, and convert the key agreed upon by both parties into a perfectly secure key; S5, Distribute the quantum key: Use the generated key to encrypt and transmit the quantum key, and securely distribute the quantum key from the edge gateway to the IoT terminal device.

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