Key generation method and system in communication system

Abstract

The invention discloses a secret key generation method and system in a communication system, and particularly relates to the technical field of communication, the secret key generation method comprises the steps that a node A and a node B send pilot frequency sequences to each other in coherence time, then receive signals sent by the opposite sides respectively, and calculate channel pilot frequency values corresponding to pilot frequency symbols through a channel algorithm; next, according to the channel pilot frequency value and the time interval corresponding to the nth pilot frequency symbol, calculating a frequency domain value, and according to the channel pilot frequency value, the frequency domain value and the phase difference, calculating to obtain a channel characteristic value; then, according to a corresponding relation between a preset frequency domain value range and a quantization method, determining a quantization range to which the current frequency domain value belongs, and performing quantization processing on the channel estimation value information by applying a corresponding quantization method; and finally, according to a quantization result, generating a final communication key through a key negotiation step.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and more specifically, to a key generation method and system in a communication system. Background Art

[0002] Communication system is a system that transmits information using electrical signals, also known as telecommunication system; communication system is widely used in various fields, including telecommunication, Internet, radio and television, military, aerospace, etc. With the continuous development of technology, communication system is also constantly updated and upgraded to meet the needs of different fields; it is composed of several units with specific functions, interactions and interdependence to achieve a unified goal as an organic whole.

[0003] With the rapid development and widespread application of information technology, the security issues of communication systems have become increasingly prominent. In the fields of wireless communications, the Internet, the Internet of Things, etc., the confidentiality, integrity and authenticity of data transmission have become the key to ensuring business continuity and user privacy; however, in actual use, there are still some shortcomings, such as the traditional key generation method can no longer meet the needs of modern society, and has the disadvantages of low security and limitations. Therefore, a key generation method and system in a communication system came into being. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a key generation method and system in a communication system to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] Step S1: The two communicating parties are set as node A and node B, and they send pilot sequences to each other within the coherence time;

[0007] Step S2: Node A and Node B respectively receive the signal sent by the other party, and calculate the channel estimation value corresponding to each pilot symbol through a channel algorithm;

[0008] Step S3: Calculate the frequency domain value and extract the channel characteristic value according to the channel pilot value and time interval corresponding to the nth pilot symbol;

[0009] Step S4: determining the quantization range to which the current frequency domain value belongs according to the corresponding relationship between the preset frequency domain value range and the quantization method, and applying the corresponding quantization method to quantize the channel estimation value information;

[0010] Step S5: According to the quantization result, the final communication key is generated through the key negotiation step.

[0011] Preferably, in step S1, node A sends its pilot sequence x within a predetermined time interval. A (t), at the same time, Node B sends its pilot sequence x B (t); x A The (t) sequence is designed to have low correlation and high autocorrelation at the receiving end so that Node B can accurately extract the channel information from the received signal. Similarly, x B (t) also has low correlation and high autocorrelation.

[0012] Preferably, when node A sends data to node B, the upper layer protocol module of node A calls the send method of its MAC object; this method further calls the SendDown method of WirelessPhy, and then sends the signal through the recv method of WirelessChannel.

[0013] On the Node B side, the WirelessChannel object receives the signal packet from Node A through its sendUp method, copies it and passes it to the WirelessPhy object of Node B for processing; Node B must be within the carrier sensing range of Node A and within the transmission radius of Node A to successfully receive the signal; if Node B is out of range, it cannot receive the signal.

[0014] When multiple nodes send signals at the same time, conflicts may occur in the wireless channel. For example, when A and C send signals at the same time, node B may detect a conflict, resulting in reception failure. In this case, CSMA / CD media access control technology is used to avoid conflicts.

[0015] The pilot signal is a signal known to both the transmitter and the receiver. The channel characteristics are estimated by comparing the differences between the transmission and reception of the pilot signal. The pilot signal needs to be reasonably distributed in time and frequency to ensure that it can accurately reflect the characteristics of the entire channel.

[0016] Preferably, in step S3, after the channel is measured, the state information of the channel at that moment can be obtained, and the state information includes a frequency domain value and a channel characteristic value;

[0017] The calculation method of the frequency domain value is as follows:

[0018] Among them, P n It is expressed as a frequency domain value, Δα is expressed as a phase difference, and Δt is expressed as a time interval;

[0019] The calculation method of phase difference is as follows:

[0020] Δα=arg(C 2 )-arg(C 1), where Δα represents the phase difference, arg represents the phase angle of the complex number, and C 2 represents the channel pilot value at node B, and C 1 represents the channel pilot value at node A;

[0021] The specific method for calculating the channel eigenvalue is as follows:

[0022] where T represents the channel eigenvalue, and C n represents the channel pilot value at the nth pilot position, P n represents the frequency domain value, and Δα represents the phase difference.

[0023] Preferably, in step S4, quantization classification is performed according to the calculated frequency domain value and different quantization processes are used; after the calculation of the channel eigenvalue is completed, quantization coding is performed on the channel eigenvalue and the frequency domain value; before this step, max-min normalization processing is performed on the channel eigenvalue to ensure that all channel eigenvalues are within the interval [0,1];

[0024] The main advantage of this processing method is that it combines the normalized channel eigenvalue with the corresponding frequency domain value to form polar coordinate points, which all fall within the unit circle, facilitating observation and analysis.

[0025] In the quantization stage, all legitimate users follow the same quantization rules, and the state information of the channel is converted into a string of bit sequences through quantization coding, thereby generating their respective initial keys; currently, common quantization methods include equiprobable quantization, uniform quantization, and minimum mean square error (MMSE) quantization; equiprobable quantization depends on the probability density function to achieve an equal probability distribution of data in different quantization intervals; uniform quantization divides the quantization interval at equal intervals; while MMSE quantization optimizes the division of the interval according to the minimum mean square error criterion;

[0026] If the calculated frequency domain value |P 0 | < J, then the frequency domain value at this time is in the small frequency domain range and fine-grained quantization is used;

[0027] If the calculated frequency domain value is in the range [J, K), then the frequency domain value at this time is in the medium frequency domain range and medium-grained quantization is used;

[0028] If the calculated frequency domain value is in the range [K, +∞), then the frequency domain value at this time is in the large frequency domain range and coarse-grained quantization is used.

[0029] Preferably, in step S5, the legitimate communicating parties first divide the original key after quantization into three-bit intervals to form multiple groups; then, perform verification on each group, and this process determines the verification result according to whether the number of "1" in the transmitted binary code is an odd number or an even number;

[0030] After completing the above steps, both parties send each other the verification value of each group and check the consistency of the verification value in the group. Only those groups with consistent verification values ​​are retained, thus completing the first round of group verification;

[0031] After the first round of group verification, the interleaving operation is performed. At this time, a 3x3 interleaving matrix is ​​used to process the key data after group verification: the data is written in the order of the first row to the third row of the matrix, and then taken out in the order of the first column to the third column.

[0032] After the interleaving operation is completed, the two parties perform the second round of group verification again according to the group verification method of the first round; finally, the two parties perform CRC verification on the remaining key data and exchange verification values; if the verification values ​​are equal, the key negotiation process ends and the final key is generated; if not, return to the initial step and start again.

[0033] Technical effects and advantages of the present invention:

[0034] The present invention provides a key generation method and system in a communication system. The present invention sends and receives a pilot sequence, and nodes A and B calculate a channel pilot value, thereby obtaining a frequency domain value and a phase difference, and finally calculating a channel characteristic value; different quantization methods are used to process channel information according to the frequency domain value range to form an initial key; through key negotiation steps, including group verification, interleaving and CRC verification, the key consistency of both parties is ensured, and finally a secure communication key is generated; this method utilizes the inherent characteristics of the channel, combines quantization and verification technology, and enhances the security and reliability of key generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the method flow of the present invention.

[0036] Figure 2 It is a schematic diagram of module connection of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] See also Figure 1 As shown, the present invention provides a key generation method in a communication system, and the method is:

[0039] Step S1: The two communicating parties are set as node A and node B, and they send pilot sequences to each other within the coherence time;

[0040] In step S1, node A sends its pilot sequence x within a predetermined time interval. A (t), at the same time, Node B sends its pilot sequence x B (t); x A The (t) sequence is designed to have low correlation and high autocorrelation at the receiving end so that Node B can accurately extract the channel information from the received signal. Similarly, x B (t) also has low correlation and high autocorrelation.

[0041] The coherence time is a time scale that describes the change of channel characteristics of a wireless channel over a period of time. During this period of time, the gain and phase changes of the channel are relatively small, making the channel estimation more accurate.

[0042] Step S2: Node A and Node B respectively receive the signal sent by the other party, and calculate the channel pilot value corresponding to each pilot symbol through a channel algorithm;

[0043] In step S2, the cost function is calculated as follows:

[0044] A(a)=(y n -Xa) I (y n -Xa), where A(a) is the cost function, y n is represented by the signal vector received at the nth pilot position, I is represented by the conjugate transpose, X is represented by the transmitted pilot signal matrix, and a is represented by the channel vector;

[0045] The calculation method of the channel pilot value is specifically as follows:

[0046] Among them, C n It is represented as the channel pilot value of the nth pilot position, S n Represented as the known transmitted pilot signal vector at the corresponding position, (S n ) I Indicated as S n The conjugate of , α represents the initial phase, Δt represents the time interval;

[0047] When node A sends data to node B, the upper layer protocol module of node A calls the send method of its MAC object; this method further calls the SendDown method of WirelessPhy, and then sends the signal through the recv method of WirelessChannel.

[0048] On the Node B side, the WirelessChannel object receives the signal packet from Node A through its sendUp method, copies it and passes it to the WirelessPhy object of Node B for processing; Node B must be within the carrier sensing range of Node A and within the transmission radius of Node A to successfully receive the signal; if Node B is out of range, it cannot receive the signal.

[0049] When multiple nodes send signals at the same time, conflicts may occur in the wireless channel. For example, when A and C send signals at the same time, node B may detect a conflict, resulting in reception failure. In this case, CSMA / CD media access control technology is used to avoid conflicts.

[0050] The pilot signal is a signal known to both the transmitter and the receiver. The channel characteristics are estimated by comparing the differences between the transmission and reception of the pilot signal. The pilot signal needs to be reasonably distributed in time and frequency to ensure that it can accurately reflect the characteristics of the entire channel.

[0051] Step S3: Calculate the frequency domain value according to the channel pilot value and time interval corresponding to the nth pilot symbol, and calculate the channel characteristic value according to the channel pilot value, the frequency domain value and the phase difference;

[0052] In step S3, after the channel is measured, the state information of the channel at that moment can be obtained, and the state information includes frequency domain value and channel characteristic value;

[0053] The calculation method of the frequency domain value is as follows:

[0054] Among them, P n It is expressed as a frequency domain value, Δα is expressed as a phase difference, and Δt is expressed as a time interval;

[0055] The calculation method of phase difference is as follows:

[0056] Δα=arg(C 2 )-arg(C 1 ), where Δα is the phase difference, arg is the complex phase angle, and C 2 It is represented as the channel pilot value at Node B, C 1 It is represented as the channel pilot value at node A;

[0057] The specific method for calculating the channel characteristic value is:

[0058] Among them, T represents the channel eigenvalue, and C n represents the channel pilot value at the nth pilot position, and P n represents the frequency-domain value, and Δα represents the phase difference.

[0059] Step S4: According to the correspondence between the preset frequency-domain value range and the quantization method, determine the quantization range to which the current frequency-domain value belongs, and apply the corresponding quantization method to quantize the channel estimation value information.

[0060] In the said step S4, quantization classification is performed according to the calculated frequency-domain value and different quantization processes are used; after the channel eigenvalue calculation is completed, quantization coding is performed on the channel eigenvalue and the frequency-domain value; before this step, max-min normalization processing is performed on the channel eigenvalue to ensure that all channel eigenvalues are within the interval [0,1];

[0061] The main advantage of this processing method is that it combines the normalized channel eigenvalue with the corresponding frequency-domain value to form polar coordinate points, and these points all fall within the unit circle, thus facilitating observation and analysis.

[0062] In the quantization stage, all legitimate users follow the same quantization rules, and the state information of the channel is converted into a string of bit sequences through quantization coding, and then their respective initial keys are generated; currently, common quantization methods include equiprobable quantization, uniform quantization, and minimum mean square error (MMSE) quantization; equiprobable quantization depends on the probability density function to achieve an equal-probability distribution of data in different quantization intervals; uniform quantization divides the quantization interval at equal intervals; while MMSE quantization optimizes the division of the interval according to the minimum mean square error criterion;

[0063] If the calculated frequency-domain value |P 0 |<J, then the current frequency-domain value is in the small frequency-domain range, and fine-grained quantization is used;

[0064] If the calculated frequency-domain value is in the range of [J, K), then the current frequency-domain value is in the medium frequency-domain range, and medium-grained quantization is used;

[0065] If the calculated frequency-domain value is in the range of [K, +∞), then the current frequency-domain value is in the large frequency-domain range, and coarse-grained quantization is used.

[0066] Step S5: According to the quantization result, generate the final communication key through the key negotiation step.

[0067] In step S5, the legitimate communicating parties first divide the original secret key into three-bit intervals to form multiple groups after quantization; then, each group is verified, and the verification result is determined according to whether the number of "1" in the transmitted binary code is odd or even;

[0068] After completing the above steps, both parties send each other the verification value of each group and check the consistency of the verification value in the group. Only those groups with consistent verification values ​​are retained, thus completing the first round of group verification;

[0069] After the first round of group verification, the interleaving operation is performed. At this time, a 3x3 interleaving matrix is ​​used to process the key data after group verification: the data is written in the order of the first row to the third row of the matrix, and then taken out in the order of the first column to the third column.

[0070] After the interleaving operation is completed, the two parties perform the second round of group verification again according to the group verification method of the first round; finally, the two parties perform CRC verification on the remaining key data and exchange verification values; if the verification values ​​are equal, the key negotiation process ends and the final key is generated; if not, return to the initial step and start again.

[0071] See also Figure 2 As shown, in this embodiment, it should be specifically explained that the present invention provides a key generation system in a communication system, including the following modules:

[0072] Acquisition channel state information module: used for the two communicating parties to be set as node A and node B, and to send pilot sequences to each other within the coherence time;

[0073] Channel pilot value calculation module: used for node A and node B to receive signals sent by each other, and calculate the channel pilot value corresponding to each pilot symbol through the channel algorithm;

[0074] Channel characteristic value calculation module: used to calculate the frequency domain value according to the channel pilot value and time interval corresponding to the nth pilot symbol, and calculate the channel characteristic value according to the channel pilot value, frequency domain value and phase difference;

[0075] Quantization processing module: used to determine the quantization range to which the current frequency domain value belongs according to the correspondence between the preset frequency domain value range and the quantization method, and apply the corresponding quantization method to quantize the channel estimation value information;

[0076] Key negotiation generation module: Based on the quantization results, the final communication key is generated through the key negotiation steps.

[0077] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for generating a key in a communication system, characterized in that: Including: Step S1: Set the two communication parties as node A and node B, and send pilot sequences to each other within the coherence time; Step S2: Node A and node B respectively receive the signals sent by the other party, and calculate the channel estimation values corresponding to each pilot symbol through the channel algorithm; Step S3: Calculate the frequency-domain value according to the channel pilot value and time interval corresponding to the nth pilot symbol, and calculate the channel eigenvalue according to the channel pilot value, frequency-domain value and phase difference; Step S4: Determine the quantization range to which the current frequency-domain value belongs according to the corresponding relationship between the preset frequency-domain value range and the quantization method, and apply the corresponding quantization method to quantize the channel estimation value information; Step S5: Generate the final communication key through the key negotiation step according to the quantization result.

2. The key generation method in a communication system according to claim 1, characterized in that: In step S1, node A sends its pilot sequence x within a predetermined time interval. A (t), at the same time, Node B sends its pilot sequence x B (t); x A The (t) sequence is designed to have low correlation and high autocorrelation at the receiving end so that Node B can accurately extract the channel information from the received signal. Similarly, x B (t) also has low correlation and high autocorrelation.

3. The key generation method in a communication system according to claim 1, characterized in that: In the said step S2, the specific calculation method of the cost function is: A(a)=(y n -Xa) I (y n -Xa), where A(a) is the cost function, y n is represented by the signal vector received at the nth pilot position, I is represented by the conjugate transpose, X is represented by the transmitted pilot signal matrix, and a is represented by the channel vector; The specific calculation method of the channel pilot value is: Among them, C n It is represented as the channel pilot value of the nth pilot position, S n Represented as the known transmitted pilot signal vector at the corresponding position, (S n ) I Indicated as S n is the conjugate of , α represents the initial phase, and Δt represents the time interval.

4. The key generation method in a communication system according to claim 1, characterized in that: In the said step S3, the state information of the channel at this moment can be obtained after channel measurement, and the state information includes the frequency-domain value and the channel eigenvalue; The specific calculation method of the frequency-domain value is: Among them, P n It is expressed as a frequency domain value, Δα is expressed as a phase difference, and Δt is expressed as a time interval; The specific calculation method of the channel eigenvalue is: Among them, T represents the channel characteristic value, C n It is represented as the channel pilot value of the nth pilot position, P n It is expressed as a frequency domain value, and Δα is expressed as a phase difference.

5. The key generation method in a communication system according to claim 4, characterized in that: If the calculated frequency-domain value |P0| < J, then the frequency-domain value at this time is in the small frequency-domain range, and fine-grained quantization is used; If the calculated frequency-domain value is in the range of [J, K), then the frequency-domain value at this time is in the medium frequency-domain range, and medium-grained quantization is used; If the calculated frequency-domain value is in the range of [K, +∞), then the frequency-domain value at this time is in the large frequency-domain range, and coarse-grained quantization is used.

6. The key generation method in a communication system according to claim 1, characterized in that: In the said step S4, quantization classification is performed according to the calculated frequency-domain value and different quantization processes are used; After the channel eigenvalue is calculated, quantization coding is performed on the channel eigenvalue and the frequency-domain value; Perform max-min normalization processing on the channel eigenvalue to ensure that all channel eigenvalues are in the interval of [0, 1]; In the quantization stage, all legitimate users follow the same quantization rules, and the state information of the channel is converted into a string of bit sequences through quantization coding, thereby generating their respective initial keys; currently, common quantization methods include equiprobable quantization, uniform quantization, and minimum mean square error (MMSE) quantization; equiprobable quantization depends on the probability density function to achieve an equiprobable distribution of data in different quantization intervals; uniform quantization divides the quantization interval at equal intervals; while MMSE quantization optimizes the division of intervals according to the minimum mean square error criterion.

7. The key generation method in a communication system according to claim 1, characterized in that: In the said step S5, the legitimate communication parties after quantization first divide the original key at intervals of every three bits to form multiple groups; then, a check is performed on each group, and this process determines the check result according to whether the number of "1"s in the transmitted binary code is odd or even; After the above steps are completed, the two parties send each other the check values of each group and check the consistency of the check values in the groups; Only retain those groups with consistent check values, thereby completing the first-round group check; After the first-round group check, an interleaving operation is performed; at this time, a 3x3 interleaving matrix is used to process the key data after group check: the data is written in the order of the first row to the third row of the matrix and then taken out in the order of the first column to the third column; After the interleaving operation is completed, both parties perform a second round of group verification according to the first round of group verification method; finally, both parties perform CRC verification on the remaining key data and exchange verification values; If the checksums are equal, the key negotiation process ends and the final key is generated; If not, return to the initial step and start again.

8. A key generation system in a communication system, using a key generation method in a communication system as claimed in any one of claims 1 to 7, characterized in that: Acquisition channel state information module: used for the two communicating parties to be set as node A and node B, and to send pilot sequences to each other within the coherence time; Channel pilot value calculation module: used for node A and node B to receive signals sent by each other, and calculate the channel pilot value corresponding to each pilot symbol through the channel algorithm; Channel characteristic value calculation module: used to calculate the frequency domain value according to the channel pilot value and time interval corresponding to the nth pilot symbol, and calculate the channel characteristic value according to the channel pilot value, frequency domain value and phase difference; Quantization processing module: used to determine the quantization range to which the current frequency domain value belongs according to the correspondence between the preset frequency domain value range and the quantization method, and apply the corresponding quantization method to quantize the channel estimation value information; Key negotiation generation module: Based on the quantization results, the final communication key is generated through the key negotiation steps.

Images