A physical layer key distribution method for 6G and an electronic device
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2023-03-30
- Publication Date
- 2026-06-19
Smart Images
Figure CN116390087B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of communication technology, and specifically relates to a physical layer key distribution method and electronic device for 6G. Background Technology
[0002] With the development of 6G, the application scenarios of wireless communication technology are becoming increasingly complex and flexible. This has further promoted the implementation and realization of concepts such as the Internet of Things, the Internet of Vehicles, and smart cities. However, due to the broadcast nature of wireless communication, its security issues have always been a hot topic of research.
[0003] Physical layer security (PLS) technologies can be broadly categorized into keyed and keyless types. Keyed PLS schemes typically employ either bit-level encryption via masking or symbol-level encryption via phase rotation. Keyless schemes, on the other hand, utilize techniques such as beamforming and power allocation to achieve channel gain and security capacity. Artificial noise is a scheme that sacrifices a small portion of communication performance for increased security capacity. However, from an implementation perspective, this artificial noise is generated using a pseudo-random number generator, and the seed number used by the generator can be considered a form of key. Therefore, artificial noise schemes can also be understood as keyed PLS schemes. Frequency hopping technology evades detection and eavesdropping by continuously changing the frequency band used for transmitting signals. Like artificial noise schemes, the generation of its frequency hopping paths also requires a key.
[0004] To ensure the effectiveness and security of these schemes, key generation and distribution are crucial issues. Traditional key cryptography provides public-key systems for key distribution, whose security comes from mathematical problems such as the Discrete Logarithm Problem (DLP). However, the ever-increasing computing power is posing threats and challenges to public-key systems.
[0005] Wireless channels possess characteristics such as spatiotemporal uniqueness, spatial distinctness, and randomness, making them an ideal source of randomness for key extraction. Current mainstream research methods quantify channel characteristics to obtain an initial key. However, due to errors, the initial key exhibits inconsistencies, requiring negotiation to remove or correct these errors. The former leads to a decrease in key generation rate, while the latter may leak key information to eavesdroppers. This type of scheme is known as the Secret Key Generation (SKG) scheme. Furthermore, due to the randomness of wireless channels, the initial key is also random at the beginning of its generation, making it impossible to apply any error control coding (ECC) beforehand to eliminate errors. Ultimately, the inconsistency of the initial key becomes the core problem. Summary of the Invention
[0006] The purpose of the embodiments in this specification is to provide a physical layer key distribution method and electronic device for 6G.
[0007] To solve the above-mentioned technical problems, the embodiments of this application are implemented in the following ways:
[0008] Firstly, this application provides a physical layer key distribution method for 6G, the method comprising:
[0009] The sending and receiving users take turns sending pilot signals to each other, and estimate the channel respectively to obtain the corresponding sending channel estimation sequence and receiving channel estimation sequence;
[0010] Based on the transmitted channel estimation sequence and the received channel estimation sequence, fuzzy phase extraction is performed to obtain the corresponding transmitted fuzzy phase information and received fuzzy phase information;
[0011] The key is encrypted and transmitted based on the sent and received fuzzy phase information.
[0012] In one embodiment, the transmitting user and the receiving user take turns sending pilot signals to each other to estimate the channel, obtaining corresponding transmit channel estimation sequences and receive channel estimation sequences, including:
[0013] The transmitting user obtains the estimated channel value based on the actual channel value and the equivalent receiver noise using a channel estimation method.
[0014] The transmitted channel estimates at different times constitute the transmitted channel estimate sequence;
[0015] The receiving user obtains the estimated channel value based on the actual channel value and the received equivalent receiver noise using a channel estimation method;
[0016] The received channel estimates at different times constitute the received channel estimate sequence.
[0017] In one embodiment, the transmitted estimated channel values at different times are uncorrelated, and the received estimated channel values at different times are uncorrelated.
[0018] In one embodiment, fuzzy phase extraction is performed based on the transmitted channel estimation sequence and the received channel estimation sequence to obtain corresponding transmitted fuzzy phase information and received fuzzy phase information, including:
[0019] The transmit channel estimation sequence and the receive channel estimation sequence are determined according to the power threshold to determine the corresponding transmit indication sequence and receive indication sequence, respectively;
[0020] The final indicator sequence is obtained based on the transmitted indicator sequence and the received indicator sequence;
[0021] Based on the final characteristic sequence, the transmitting and receiving users respectively perform phase extraction on the reserved channel to obtain the corresponding transmitted fuzzy phase information and received fuzzy phase information.
[0022] In one embodiment, the transmit channel estimation sequence and the receive channel estimation sequence are respectively determined according to a power threshold to form corresponding transmit indication sequences and receive indication sequences, including:
[0023] The amplitude of each transmitted channel estimation value in the transmitted channel estimation sequence is compared with a power threshold. The indicator value corresponding to the transmitted channel estimation amplitude being greater than the power threshold is recorded as 1, and the indicator value corresponding to the transmitted channel estimation amplitude being less than or equal to the power threshold is recorded as 0, thus obtaining the transmitted indicator sequence.
[0024] The amplitude of each received channel estimate value in the received channel estimation sequence is compared with a power threshold. The indicator value corresponding to the received channel estimate amplitude being greater than the power threshold is recorded as 1, and the indicator value corresponding to the received channel estimate amplitude being less than or equal to the power threshold is recorded as 0, thus obtaining the received indicator sequence.
[0025] In one embodiment, the final indication sequence is obtained based on the transmitted indication sequence and the received indication sequence, including:
[0026] The sending user sends the transmitted characteristic sequence to the receiving user, and the receiving user performs a bitwise AND operation between the transmitted characteristic sequence and the received characteristic sequence to obtain the final characteristic sequence; the receiving user sends the received characteristic sequence to the sending user, and the sending user performs a bitwise AND operation between the transmitted characteristic sequence and the received characteristic sequence to obtain the final characteristic sequence.
[0027] In one embodiment, without considering encoding, the key is encrypted and transmitted based on the transmitted and received fuzzy phase information, including:
[0028] Send the user-generated local key;
[0029] The sending user modulates the local key to obtain modulation symbols;
[0030] The transmitting user performs phase rotation encryption on the modulation symbol by transmitting ambiguous phase information to obtain the encrypted symbol;
[0031] The encrypted symbols are received by the receiving user through the channel, resulting in a received signal;
[0032] The receiving user decrypts the received signal by performing an anti-phase rotation using the received ambiguous phase information to obtain the decrypted signal.
[0033] The system receives and demodulates the decryption signal from the user to obtain the key.
[0034] Send the user the first hash value or first parity value of the local key;
[0035] Receive the second hash value or second parity value of the user's calculated key;
[0036] Consistency checks are performed by sharing either the first hash value and the second hash value, or by sharing either the first parity value or the second parity value.
[0037] In one embodiment, when considering encoding, the key is encrypted and transmitted based on the transmitted and received fuzzy phase information, including:
[0038] Send the user-generated local key;
[0039] The user encodes the local key to obtain the encoded local key;
[0040] The sending user modulates the encoded local key to obtain the modulation symbol;
[0041] The transmitting user performs phase rotation encryption on the modulation symbol by transmitting ambiguous phase information to obtain the encrypted symbol;
[0042] The encrypted symbols are received by the receiving user through the channel, resulting in a received signal;
[0043] The receiving user decrypts the received signal by performing an anti-phase rotation using the received ambiguous phase information to obtain the decrypted signal.
[0044] The system receives and demodulates the decryption signal from the user to obtain the encoded key.
[0045] The user decodes the encoded key to obtain the new key.
[0046] In one embodiment, the method further includes:
[0047] Send the user the first hash value or first parity value of the local key;
[0048] Receive the second hash value or second parity value of the user's calculated key;
[0049] Consistency checks are performed by sharing either the first hash value and the second hash value, or by sharing either the first parity value or the second parity value.
[0050] In a second aspect, this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the physical layer key distribution method as described in the first aspect.
[0051] As can be seen from the technical solutions provided in the embodiments of this specification above, this solution: extracts fuzzy phase information from the wireless channel, and uses it for phase rotation encryption and decryption of the key when the information is not completely consistent. It directly uses the inconsistent channel features for the encryption distribution of the key, reduces the probability of key mismatch while ensuring security performance, and allows users to further improve the noise resistance of the key distribution process through error correction coding, thereby reducing the key leakage problem caused by the negotiation process. Attached Figure Description
[0052] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0053] Figure 1 A flowchart illustrating the physical layer key distribution method provided in this application;
[0054] Figure 2 Another flowchart illustrating the physical layer key distribution method provided in this application;
[0055] Figure 3 A schematic diagram of the signal format for the key encryption distribution stage provided in this application;
[0056] Figure 4 A comparative diagram of the method provided in this application and existing CQA and CQG solutions;
[0057] Figure 5 The bit error probabilities of the method provided in this application under different modulation schemes;
[0058] Figure 6 The secure key rate of the physical layer key distribution method provided in this application under different modulation schemes;
[0059] Figure 7 A schematic diagram of the structure of the electronic device provided in this application. Detailed Implementation
[0060] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.
[0061] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.
[0062] Various modifications and variations can be made to the specific embodiments described in this application without departing from the scope or spirit of this application, as will be apparent to those skilled in the art. Other embodiments derived from this application will be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.
[0063] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0064] Unless otherwise specified, "parts" in this application refers to parts by weight.
[0065] Existing channel-based physical layer key extraction technologies typically employ a sampling, quantization, and negotiation process to extract keys. However, the inconsistency of the initial channel leads to inconsistencies in the initial keys obtained through quantization. Traditional schemes use negotiation to delete or correct erroneous bits, but negotiation itself can result in low key generation rates or key leakage. Ultimately, the inconsistency of the initial key becomes the core problem.
[0066] To address the aforementioned shortcomings, this application proposes a physical layer key distribution method for 6G. This method directly uses the not-so-consistent channel characteristics for encrypted key distribution without quantization, reducing the impact of inconsistencies in channel observations by legitimate users. Furthermore, the key distribution process reduces the probability of key mismatch while ensuring security performance. It also allows users to further improve the noise resistance of the key distribution process through error correction coding, reducing communication overhead and key leakage issues caused by the negotiation process.
[0067] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0068] Reference Figure 1 and Figure 2 This illustrates a flowchart of the physical layer key distribution method applicable to the embodiments of this application. For example... Figure 2 As shown, the physical layer key distribution method provided in this application can be divided into three stages: the first stage is channel estimation, the second stage is fuzzy phase extraction, and the third stage is key encryption distribution.
[0069] like Figure 1 As shown, the physical layer key distribution method may include:
[0070] Channel estimation stage
[0071] S110. The transmitting user and the receiving user take turns sending pilot signals to each other, and estimate the channel respectively to obtain the corresponding transmitting channel estimation sequence and receiving channel estimation sequence, which may include:
[0072] The transmitting user obtains the estimated channel value based on the actual channel value and the equivalent receiver noise using a channel estimation method.
[0073] The transmitted channel estimates at different times constitute the transmitted channel estimate sequence;
[0074] The receiving user obtains the estimated channel value based on the actual channel value and the received equivalent receiver noise using a channel estimation method;
[0075] The received channel estimates at different times constitute the received channel estimate sequence.
[0076] Among them, the estimated channel values for transmission at different times are uncorrelated, and the estimated channel values for reception at different times are also uncorrelated.
[0077] Specifically, assume that the sending user and the receiving user are legitimate users Alice and Bob, abbreviated as A and B.
[0078] Alice and Bob take turns sending pilot signals to each other and estimating the channel. Assuming Bob sends a pilot signal p to Alice, the signal received by Alice will have the following format:
[0079] y A，1 =h 1p +z A，1
[0080] Where |p| 2 =1, h1 is the actual channel value in the first stage, z A，1 This is the receiver noise at Alice in the first stage.
[0081] Using channel estimation methods, Alice can obtain the estimated channel value, which is equal to the sum of the true channel value and the equivalent receiver noise.
[0082]
[0083] Using the same method, Bob obtained the received estimated channel value:
[0084]
[0085] Assume the real channel follows a zero-mean complex Gaussian distribution with a mean of 1, i.e. Receiver noise follows a variance of σ 2 Gaussian noise, i.e. Define γ = 1 / σ 2 The signal-to-noise ratio (SNR) is used to calculate the signal-to-noise ratio. The distribution of the equivalent receiver noise depends on the specific channel estimation method. In the least squares estimation method, the power of the equivalent noise is consistent with the power of the original noise, i.e.,
[0086] To extract a sufficient amount of fuzzy phase information, a channel estimation sequence of length N should be prepared. and Furthermore, to avoid security performance degradation due to channel correlation, channel estimates at different times should be uncorrelated, which can be defined by coherence bandwidth or coherence time. Additionally, channel estimation does not need to be immediately adjacent to subsequent stages; it can be completed well before key distribution.
[0087] Regarding the selection of channel features, for security reasons, these features should carry as little information as possible. Since the phase in a Rayleigh channel follows a uniform distribution, the phase becomes a highly desirable ambiguity feature. This is why phase rotation encryption is used in the third stage.
[0088] Due to the presence of channel noise, the extracted phase is also affected by the noise. Obviously, the larger the channel amplitude, the smaller the phase noise. Therefore, power filtering of the sampling channel can greatly reduce the range of phase noise.
[0089] Understandably, during the channel estimation phase, the channel sampling of Alice and Bob at the same time should be as correlated as possible; while the channels of the same user at different times should be as uncorrelated as possible.
[0090] Fuzzy phase extraction stage
[0091] S120. Based on the transmitted channel estimation sequence and the received channel estimation sequence, perform fuzzy phase extraction to obtain the corresponding transmitted fuzzy phase information and received fuzzy phase information, including:
[0092] The transmit channel estimation sequence and the receive channel estimation sequence are determined according to the power threshold to determine the corresponding transmit indication sequence and receive indication sequence, respectively;
[0093] The final indicator sequence is obtained based on the transmitted indicator sequence and the received indicator sequence;
[0094] Based on the final characteristic sequence, the transmitting and receiving users respectively perform phase extraction on the reserved channel to obtain the corresponding transmitted fuzzy phase information and received fuzzy phase information.
[0095] The transmit channel estimation sequence and receive channel estimation sequence are determined according to a power threshold, respectively, to form the corresponding transmit indication sequence and receive indication sequence, including:
[0096] The amplitude of each transmitted channel estimation value in the transmitted channel estimation sequence is compared with a power threshold. The indicator value corresponding to the transmitted channel estimation amplitude being greater than the power threshold is recorded as 1, and the indicator value corresponding to the transmitted channel estimation amplitude being less than or equal to the power threshold is recorded as 0, thus obtaining the transmitted indicator sequence.
[0097] The amplitude of each received channel estimate value in the received channel estimation sequence is compared with a power threshold. The indicator value corresponding to the received channel estimate amplitude being greater than the power threshold is recorded as 1, and the indicator value corresponding to the received channel estimate amplitude being less than or equal to the power threshold is recorded as 0, thus obtaining the received indicator sequence.
[0098] The final indication sequence is obtained based on the transmitted indication sequence and the received indication sequence, including:
[0099] The sending user sends the transmitted characteristic sequence to the receiving user, and the receiving user performs a bitwise AND operation between the transmitted characteristic sequence and the received characteristic sequence to obtain the final characteristic sequence; the receiving user sends the received characteristic sequence to the sending user, and the sending user performs a bitwise AND operation between the transmitted characteristic sequence and the received characteristic sequence to obtain the final characteristic sequence.
[0100] Specifically, the input in the fuzzy phase extraction stage is the channel estimation sequence. and and power threshold Where μ is the normalized power threshold.
[0101] Alice and Bob compared the power of their respective channel observation sequences, retaining channels with power greater than a power threshold and discarding channels with power less than the power threshold, thus obtaining the indicator sequence I. A and I B In the indicative sequence, the channel to be retained is marked as 1, and the channel to be discarded is marked as 0; that is, Alice and Bob respectively calculate the indicative value of whether the amplitude of the sampled channel is greater than the power threshold δ:
[0102]
[0103] Where x∈{A, B}. The characteristic sequence is I. x =[I x [1], I x [2], ..., I x [n],...,Ix [N]].
[0104] Alice and Bob each perform a bitwise AND operation on their local characteristic sequences and the other's characteristic sequence to obtain the final characteristic sequence I0. That is, Alice sets her characteristic sequence I0... A Send it to Bob, who then sends his characteristic sequence I. B The sequence is sent to Alice, and both parties obtain the final characteristic sequence through a bitwise AND operation:
[0105]
[0106] And I0 = [I[1], I[2], ..., I[n], ..., I[N]].
[0107] Alice and Bob retained the channels whose power was greater than the power threshold in both of their estimates.
[0108] Based on the final indicative sequence I0, Alice and Bob each perform phase extraction on the preserved channel to obtain fuzzy phase information Φ of length L. A and Φ B That is, Alice and Bob perform phase extraction Φ based on the final indicator sequence I0. x ={φ x，1 [n]|I0[n]=1}, where, represent The phase value.
[0109] The phase extraction filtering process described above is essentially filtering channels where "the channel estimates of both communicating parties are greater than the power threshold," and the number of generated phases L will always be less than N. The number of generated phases is related to the SNR and the power threshold δ. Let the magnitude of h1 be... The probability density function (PDF) for the modulus is:
[0110]
[0111] When h1 is given and The modulus m A and m B It follows a Rice distribution, and its cumulative distribution function (CDF) is shown in the following equation:
[0112]
[0113] Where Q1(a, b) is the Marcum Q function.
[0114] We can derive the following:
[0115]
[0116] The above formula has been verified by simulation and can be used to calculate the phase information generation ratio at a specified SNR and δ.
[0117] Key encryption distribution phase
[0118] The previous stage has already produced fuzzy phase information Φ A and Φ B In this stage, the key will be encrypted and transmitted. Without loss of generality, assume Alice is the initiator of the key transmission and Bob is the receiver. Their roles can be interchanged.
[0119] S130. Based on the sent and received fuzzy phase information, the key is encrypted and transmitted.
[0120] In one embodiment, without considering encoding, S130 encrypts and transmits the key based on the transmitted and received fuzzy phase information, which may include:
[0121] Send the user-generated local key;
[0122] The sending user modulates the local key to obtain modulation symbols;
[0123] The transmitting user performs phase rotation encryption on the modulation symbol by transmitting ambiguous phase information to obtain the encrypted symbol;
[0124] The encrypted symbols are received by the receiving user through the channel, resulting in a received signal;
[0125] The receiving user decrypts the received signal by performing an anti-phase rotation using the received ambiguous phase information to obtain the decrypted signal.
[0126] The system receives and demodulates the decryption signal from the user to obtain the key.
[0127] Send the user the first hash value or first parity value of the local key;
[0128] Receive the second hash value or second parity value of the user's calculated key;
[0129] Consistency checks are performed by sharing either the first hash value and the second hash value, or by sharing either the first parity value or the second parity value.
[0130] In one embodiment, when considering encoding, S130 encrypts and transmits the key based on the transmitted and received fuzzy phase information, which may include:
[0131] Send the user-generated local key;
[0132] The user encodes the local key to obtain the encoded local key;
[0133] The sending user modulates the encoded local key to obtain the modulation symbol;
[0134] The transmitting user performs phase rotation encryption on the modulation symbol by transmitting ambiguous phase information to obtain the encrypted symbol;
[0135] The encrypted symbols are received by the receiving user through the channel, resulting in a received signal;
[0136] The receiving user decrypts the received signal by performing an anti-phase rotation using the received ambiguous phase information to obtain the decrypted signal.
[0137] The system receives and demodulates the decryption signal from the user to obtain the encoded key.
[0138] The user decodes the encoded key to obtain the new key.
[0139] When considering encoding, once the key is obtained, there is no need for verification or only one verification is required.
[0140] When validating once, the method also includes:
[0141] Send the user the first hash value or first parity value of the local key;
[0142] Receive the second hash value or second parity value of the user's calculated key;
[0143] Consistency checks are performed by sharing either the first hash value and the second hash value, or by sharing either the first parity value or the second parity value.
[0144] Specifically, the transmission process, without considering encoding, includes the following steps:
[0145] 1) Alice generates a local key. A ;
[0146] 2) Alice's Key A Modulation is performed to obtain the modulation symbol s A ;
[0147] 3) Alice uses its fuzzy phase information Φ A For modulation symbol s A Phase rotation encryption is performed, and the resulting transmitted symbol (i.e., encrypted symbol) is:
[0148] 4) The encrypted symbol is received by Bob through the channel. Bob receives the signal as follows:
[0149] 5) Bob uses its fuzzy phase information Φ B The received signal is decrypted by performing an inverse phase rotation, resulting in the decrypted signal:
[0150]
[0151] 6) Bob demodulates the decryption signal to obtain the key. B ;
[0152] 7) Alice and Bob each calculate the key. A and Key B The hash value or parity value is shared to complete the consistency check. This check requires negotiation to delete or correct inconsistent bits.
[0153] It is important to note that in the anti-phase rotation decryption formula, symbol recovery is primarily affected by phase noise and receiver noise; the uniformly distributed phase information does not affect the Gaussian-distributed noise, i.e. With z B，2 The distribution is consistent.
[0154] Taking QPSK modulation as an example, the signal format in the above process is as follows: Figure 3 As shown, Figure 3 (a) is a QPSK modulation symbol; Figure 3 (b) Alice transmits symbols after phase rotation; Figure 3 (c) Bob receives the signal; Figure 3 (d) is the QPSK symbol obtained after Bob undergoes phase inversion rotation.
[0155] The encoded transmission process includes the following steps:
[0156] 1) Alice generates a local key. A ;
[0157] 2) Alice's local key Key A Encode the key to obtain the encoded local key CKey. A =enc(Key) A );
[0158] 3) Alice's CKey A Modulation is performed to obtain the modulation symbol s A ;
[0159] 4) Alice uses its fuzzy phase information Φ A For modulation symbol s A Phase rotation encryption is performed, and the resulting transmitted symbol (i.e., encrypted symbol) is:
[0160] 5) The encrypted symbol is received by Bob through the channel. Bob receives the signal as follows:
[0161] 6) Bob uses its fuzzy phase information Φ B The received signal is decrypted by performing an inverse phase rotation, resulting in the decrypted signal:
[0162]
[0163] 7) Bob demodulates the decrypted signal to obtain the encoded key CKey. B ;
[0164] 8) Bob to CKey B Decode to obtain the Key B =dec(CKey) B ).
[0165] After step 8) of the transmission process, no verification is required or only one verification is needed.
[0166] Where enc(·) and dec(·) are the encoder and decoder of the error correction code, respectively.
[0167] Understandably, the modulation schemes mentioned above can be QPSK, 8PSK, 16PSK, 8QAM, 16QAM, or even higher-order modulation schemes. When using higher-order QAM modulation, the symbol power can be exploited by eavesdroppers to obtain key information. In the simulation results of specific embodiments, it can be seen that the PSK modulation scheme provides the highest key security.
[0168] The physical layer key distribution method provided in this application extracts fuzzy phase information from the wireless channel and, when the information is not completely consistent, uses it for phase rotation encryption and decryption of the key. The advantages of this scheme are:
[0169] 1) Compared with the traditional SKG scheme, this application is much less sensitive to inconsistencies in information extracted from the channel.
[0170] 2) Allows users to achieve higher fault tolerance by encoding the key for error correction; this scheme allows for two methods to achieve consistency of the final key: encoding before transmission and negotiation after transmission, which is highly flexible.
[0171] 3) Simulation results show that, under the condition of no encoding and consistent key generation rate, the key bit inconsistency rate of the proposed scheme is lower than that of the traditional SKG scheme.
[0172] 4) Simulation results show that, under the conditions of no encoding and the same key bit inconsistency rate, the proposed scheme has a higher key generation rate.
[0173] 5) Simulation results show that, under the conditions of no encoding and the same key bit inconsistency rate, PSK modulation can achieve a higher security key extraction rate than QAM modulation.
[0174] Security analysis and modulation method selection
[0175] When all points in the constellation diagram of a modulation scheme have the same power (such as QPSK, 8PSK, etc.), an eavesdropper cannot obtain the true symbol phase through brute-force search. Furthermore, since the channel at different times is uncorrelated, an eavesdropper cannot estimate the uniformly distributed phase information through statistical analysis. Therefore, it can be considered that an eavesdropper cannot crack the phase rotation encryption method. However, when different power points exist in the constellation diagram (such as 8QAM, 16QAM), an eavesdropper can obtain partial information about the symbol through power (modulus), which poses a certain threat to the system's security performance. Specifically, for 8QAM modulation, which contains constellation points with two power levels, each with a probability of 1 / 2, the amount of information leaked is I. leak，8QAM = 2 × 1 / 2 × (-log2(1 / 2)) = 1 bit; For 16QAM modulation, which contains three types of star points with probabilities of 1 / 4, 1 / 2, and 1 / 4 respectively, the amount of information leaked is I. leak，16QAM = 2 × 1 / 4 × (-log2(1 / 4)0 + 1 / 2 × (-log2(1 / 2))) = 1.5 bits. Therefore, if the eavesdropper can accurately estimate the modulation symbol power, the 8QAM modulation method carries only 2 bits of security information, which is equivalent to QPSK; the 16QAM modulation method carries 2.5 bits of security information. In reality, the eavesdropper is affected by noise, and there is a certain error in the estimation of symbol power, which may lead to an increase in the security information. This point will be discussed and verified in the simulation.
[0176] Experimental simulation
[0177] A. Reference Indicators
[0178] From the above description, we have obtained the amount of phase information L. Then, one phase information is used to encrypt one modulation symbol, and each modulation symbol carries qbits of information. If these bits can be transmitted securely, then according to the one-time pad principle, these phases can be considered to achieve the encryption effect of Lqbits. This understanding helps in comparing the proposed scheme with the traditional quantization-based SKG scheme. Reference metrics are shown below:
[0179] (1) Bit Generation Rate (BGR). For the traditional SKG scheme, BGR is defined as the average number of keys that can be generated per channel. In this application, the equivalent BGR is defined as:
[0180]
[0181] (2) Bit Error Rate (BER), also known as Bit Mismatch Rate (BMR). An error is considered to have occurred when the keys generated by legitimate users do not match. Due to the influence of phase noise and AWGN noise, errors will inevitably exist between legitimate users. The statistical average of these errors is denoted as BER.
[0182] (3) Leaked Entropy. This metric primarily targets the entropy leaked through constellation power in high-order QAM modulation. Here, it is assumed that the eavesdropper Eve has the same signal-to-noise ratio as Bob and can intercept the selected sequence I. A and I B However, Eve's channel is independent of the legitimate user's channel. Eve can obtain information entropy about the key by guessing the channel power: if the guess matches the actual power, it is considered that information entropy has been leaked. The amount of leaked entropy is related to the ratio of the number of constellation points with the same power to the total number of points. For example, when the outermost constellation point of 16QAM leaks, the amount of leaked information is -log2(4 / 16) = 2 bits, and the amount of leaked information in the middle layer is -log2(8 / 16) = 1 bit.
[0183] (4) Secure Key Rate (SKR). SKR = BGR – Leaked Entropy. This metric represents the number of secure keys that the system can transmit and is more important than BGR.
[0184] B. Comparison with other SKG solutions
[0185] Figure 4This paper compares the proposed scheme with existing Channel Quantization Alternating (CQA) and Channel Quantization with Guardband (CQG) schemes, where BGR = 1.02 bits / symbol. Comparative experiments were conducted for q = 2 and q = 4. When q = 2, CQA and CQG each have 4 quantization intervals, extracting 2 bits of information from one channel. The proposed FSKG scheme uses QPSK to modulate the key. When q = 4, CQA and CQG each have 16 quantization intervals, extracting 4 bits of information from one channel. The proposed FSKG scheme uses 16PSK to modulate the key. To control variables, the bit generation rate (BGR) of the three schemes remains strictly consistent. Since the proposed scheme only uses phase information as an encryption method, CQA and CQG technologies also only use phase information for key extraction.
[0186] Simulation results show that, when the signal-to-noise ratio is high, the proposed scheme has a lower bit error probability (BER) than traditional CQA and CQG techniques.
[0187] C. Comparison of different modulation methods
[0188] Figure 5 The bit error rate (BER) of the proposed scheme under different modulation schemes is shown, where BGR = 1.02 bits / symbol. It can be seen that QPSK has the lowest BER, while 16PSK has the highest. The curves for 8PSK, 8QAM, and 16QAM are relatively similar. When the signal-to-noise ratio (SNR) is less than 18 dB, 8QAM has the lowest BER, while when the SNR is greater than 18 dB, 8PSK has the lowest SNR.
[0189] Figure 6 The secure key rate (SKR) of the proposed scheme under different modulation schemes is shown, where BER = 0.01. BER consistency is achieved by searching the power filtering threshold. It can be seen that when the signal-to-noise ratio (SNR) is sufficiently high, the SKR of 8QAM approaches 2 bits / symbol, and the SKR of 16QAM approaches 2.8 bits / symbol. Notably, the PSK curve is consistently above the QAM curve: QPSK has the highest SKR in the 0-16dB range, 8PSK is optimal in the 16-23dB range, and 16PSK is optimal above 23dB.
[0190] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 7The diagram shows a structural schematic of an electronic device 700 suitable for implementing embodiments of this application.
[0191] like Figure 7 As shown, the electronic device 700 includes a central processing unit (CPU) 701, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 702 or a program loaded from a storage section 708 into a random access memory (RAM) 703. The RAM 703 also stores various programs and data required for the operation of the device 700. The CPU 701, ROM 702, and RAM 703 are interconnected via a bus 704. An input / output (I / O) interface 705 is also connected to the bus 704.
[0192] The following components are connected to the I / O interface 705: an input section 706 including a keyboard, mouse, etc.; an output section 707 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 708 including a hard disk, etc.; and a communication section 709 including a network interface card such as a LAN card, modem, etc. The communication section 709 performs communication processing via a network such as the Internet. A drive 710 is also connected to the I / O interface 705 as needed. A removable medium 711, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 710 as needed so that computer programs read from it can be installed into the storage section 708 as needed.
[0193] In particular, according to embodiments of this disclosure, the above references Figure 1 The described process can be implemented as a computer software program. For example, embodiments of this disclosure include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program containing program code for performing the physical layer key distribution method described above. In such embodiments, the computer program can be downloaded and installed from a network via communication section 709, and / or installed from removable medium 711.
[0194] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.
[0195] The units or modules described in the embodiments of this application can be implemented in software or hardware. The described units or modules can also be located in a processor. The names of these units or modules do not necessarily constitute a limitation on the unit or module itself.
[0196] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, laptop computer, mobile phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices. In addition to personal applications, typical implementations of this solution also include wireless terminals such as sensors, cameras, intelligent vehicles, and intelligent robotic arms, or access point (AP) devices such as base stations and WiFi.
[0197] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.
[0198] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.
Claims
1. A physical layer key distribution method for 6G, characterized in that, The method includes: The sending and receiving users take turns sending pilot signals to each other, and estimate the channel respectively to obtain the corresponding sending channel estimation sequence and receiving channel estimation sequence; Based on the transmitted channel estimation sequence and the received channel estimation sequence, fuzzy phase extraction is performed to obtain corresponding transmitted fuzzy phase information and received fuzzy phase information. This includes: determining the transmitted indication sequence and the received indication sequence according to a power threshold, respectively, including: comparing the amplitude of each transmitted estimated channel value in the transmitted channel estimation sequence with the power threshold; recording the indication value corresponding to a transmitted estimated channel amplitude greater than the power threshold as 1, and recording the indication value corresponding to a transmitted estimated channel amplitude less than or equal to the power threshold as 0, thus obtaining the transmitted indication sequence; comparing the amplitude of each received estimated channel value in the received channel estimation sequence with the power threshold; recording the indication value corresponding to a received estimated channel amplitude greater than the power threshold as 1, and recording the indication value corresponding to a received estimated channel amplitude less than or equal to the power threshold as 0, thus obtaining the received indication sequence; exchanging indication sequences between the transmitting user and the receiving user and performing an AND operation to obtain the final indication sequence; based on the final indication sequence, the transmitting user and the receiving user perform phase extraction on the channels whose power is greater than the power threshold in their respective estimates, and taking the principal argument value as the corresponding transmitted fuzzy phase information and received fuzzy phase information; The key is encrypted and transmitted according to the transmitted fuzzy phase information and the received fuzzy phase information, including: using the transmitted fuzzy phase information to perform phase rotation encryption on the modulation symbol to obtain an encrypted symbol, the encrypted symbol being transmitted through the channel and received by the receiving user, and the receiving user using the received fuzzy phase information to perform anti-phase rotation decryption on the received signal to obtain a decrypted signal.
2. The method of claim 1, wherein, The transmitting user and the receiving user take turns sending pilot signals to each other to estimate the channel, obtaining corresponding transmitting channel estimation sequences and receiving channel estimation sequences, including: The transmitting user obtains the estimated channel value based on the actual channel value and the equivalent receiver noise using a channel estimation method. The transmitted channel estimates at different times constitute the transmitted channel estimation sequence; The receiving user obtains the estimated channel value based on the actual channel value and the received equivalent receiver noise using a channel estimation method; The received channel estimates at different times constitute the received channel estimate sequence.
3. The method of claim 2, wherein, The estimated channel values for transmission at different times are uncorrelated, and the estimated channel values for reception at different times are also uncorrelated.
4. The method of claim 1, wherein, Without considering encoding, the step of encrypting and transmitting the key based on the transmitted fuzzy phase information and the received fuzzy phase information includes: Send the user-generated local key; The user modulates the local key to obtain modulation symbols; The transmitting user uses the transmitted ambiguous phase information to perform phase rotation encryption on the modulation symbol to obtain an encrypted symbol; The encrypted symbol is received by the receiving user through the channel, and a received signal is obtained; The receiving user uses the received ambiguous phase information to perform anti-phase rotation decryption on the received signal to obtain a decrypted signal; The user demodulates the decryption signal to obtain the key; The user calculates the first hash value or the first parity value of the local key; Receive the user's calculation of the second hash value or second parity value of the key; Consistency verification is completed by sharing the first hash value and the second hash value or by sharing the first parity value and the second parity value.
5. The method according to claim 1, characterized in that, When considering encoding, the step of encrypting and transmitting the key based on the transmitted fuzzy phase information and the received fuzzy phase information includes: Send the user-generated local key; The user encodes the local key to obtain the encoded local key; The user modulates the encoded local key to obtain modulation symbols; The transmitting user uses the transmitted ambiguous phase information to perform phase rotation encryption on the modulation symbol to obtain an encrypted symbol; The encrypted symbol is received by the receiving user through the channel, and a received signal is obtained; The receiving user uses the received ambiguous phase information to perform anti-phase rotation decryption on the received signal to obtain a decrypted signal; The user demodulates the decryption signal to obtain the encoded key; The user decodes the encoded key to obtain the new key.
6. The method according to claim 5, characterized in that, The method further includes: The user calculates the first hash value or the first parity value of the local key; Receive the user's calculation of the second hash value or second parity value of the key; Consistency verification is completed by sharing the first hash value and the second hash value or by sharing the first parity value and the second parity value.
7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the physical layer key distribution method as described in any one of claims 1-6.