CN112073966A - Key extraction method and system based on wireless channel characteristics - Google Patents
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Abstract
The invention discloses a key extraction method and a system based on wireless channel characteristics, wherein in the scheme, a phase value sequence is screened by an amplitude value sequence and an amplitude screening threshold value, so that the condition that the key inconsistency rate is higher when the amplitude of a CFR estimation value is too large or too small due to random noise or other interference and the like can be effectively avoided, and the key inconsistency rate is reduced; in addition, the equal probability quantization area of the other communication party is determined according to the quantization mapping value sequence transmitted by the one communication party, so that the inconsistency rate of the keys generated by the two communication parties can be further reduced; furthermore, when the phase value sequence is screened, the phase value which is easy to quantize inconsistent key bits is deleted pertinently, so that the deleted data is less, and therefore, the generation rate of the key can be improved under the condition of ensuring the lower inconsistent rate of the key.
Description
Technical Field
The present invention relates to the field of communication security and transmission technologies, and in particular, to a key extraction method and system based on wireless channel characteristics.
Background
With the widespread use of wireless sensor networks, cryptography-based security mechanisms face many challenges in computational complexity and security, and physical layer key extraction has been widely studied as an alternative solution. The physical layer key extraction process generally comprises four steps of channel detection, feature quantization, information negotiation and privacy enhancement. The characteristic quantization means that two legal communication parties respectively quantize the channel characteristic measurement values obtained by respective detection into binary sequences so as to obtain an initial key. The characteristic quantization method can directly influence two mutually restricted performance indexes, namely the key inconsistency rate and the key generation rate in the key extraction process, and is a very important step in the key extraction process.
At present, the characteristic quantization in the key extraction of the physical layer is widely researched at home and abroad, and a plurality of characteristic quantization methods are proposed. The main characteristic Quantization methods include a double-threshold Quantization method, a Channel Quantization with Guard-band (CQG) method with a Guard isolation band, and a Channel Quantization (CQA) method based on interaction error. Although the double-threshold quantization method can ensure a low key inconsistency rate, more channel characteristic measurement values are discarded, and one channel characteristic measurement value can only be quantized to obtain a 1-bit key, so that the key generation rate is low. Both the CQG and CQA methods perform multi-bit quantization on channel characteristic measurement values and reduce the inconsistency rate of the quantization results through a certain amount of information interaction. The CQG method reduces the key inconsistency rate by removing the channel characteristic measurement values falling within the guard interval, but also reduces the key generation rate. The improved CQG method deletes the channel characteristic measurement values of the two communication parties only when the channel characteristic measurement values are located in different protection isolation areas, and compared with the original CQG method, the key generation rate is obviously improved. The CQA method adjusts the quantization area by transmitting the quantization mapping value sequence on the public channel, reduces the key inconsistency rate of the two parties while not deleting any channel characteristic measurement value, and the key inconsistency rate and the key generation rate are the highest among the three quantization methods.
However, since the key inconsistency rate and the key generation rate are a pair of mutually constrained performance indexes, it is difficult for the above-mentioned feature quantization method in the existing scheme to simultaneously satisfy the lower key inconsistency rate and the higher key generation rate, and therefore, how to ensure the lower key inconsistency rate and simultaneously improve the key generation rate is a technical problem that needs to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide a key extraction method, a device, equipment and a storage medium based on wireless channel characteristics, so as to ensure a lower key inconsistency rate and improve the key generation rate.
In order to achieve the above object, the present invention provides a key extraction method based on wireless channel characteristics, including:
both communication parties determine a CFR estimation value by using a detection signal sent by the other party; the CFR estimation value comprises an amplitude value sequence and a phase value sequence;
the two communication parties screen the phase value sequence according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence screened by the two communication parties;
a communication party determines an equal probability quantization area and a sub-area of each equal probability quantization area, and determines an equal probability quantization area and a sub-area in which each phase value in a target phase value sequence of the communication party falls; generating a first key according to the code of each equal probability quantization region, generating a quantization mapping value sequence according to the quantization mapping value of each sub-region, and sending the quantization mapping value sequence to the other communication party;
and the other communication party divides the equal probability quantization regions according to the quantization mapping value sequence, determines the equal probability quantization region into which each phase value in the target phase value sequence of the other communication party falls, and generates a second key according to the coding of each equal probability quantization region which falls.
Wherein, the both communication parties determine the CFR estimated value by using the detection signal sent by the other party, and the method comprises the following steps:
the two communication parties determine CFR estimated values of the two communication parties by using pilot frequency information in the detection signals transmitted by the other communication parties.
The method for filtering the phase value sequence by the two communication parties according to the amplitude value sequence and the amplitude filtering threshold value to obtain a target phase value sequence filtered by the two communication parties includes:
the two communication parties calculate corresponding amplitude cumulative distribution functions by using the amplitude value sequence;
determining an upper threshold value and a lower threshold value of the two communication parties according to the amplitude cumulative distribution function and a preset amplitude abnormal ratio;
the communication parties detect the amplitude value sequence, if the detected amplitude value is larger than the lower threshold value and smaller than the upper threshold value, the amplitude abnormal marking value of the detected amplitude value is recorded as a first marking value, otherwise, the amplitude abnormal marking value is recorded as a second marking value, and a marking value sequence is generated;
and the two communication parties send the respectively generated mark value sequences to the other party, compare the mark value sequences sent by the other party with the mark value sequences generated by the two communication parties, and if the amplitude abnormal mark values of the same target amplitude value are the second mark values, delete the phase value corresponding to the target amplitude value from the phase value sequence to obtain the target phase value sequences screened by the two communication parties.
Wherein, the determining the upper threshold value and the lower threshold value of the two communication parties according to the amplitude cumulative distribution function and the preset amplitude abnormal proportion comprises:
the communication party is according to the preset amplitude abnormal proportionDetermining the upper threshold value as:determining the lower threshold value as follows:(ii) a Wherein,a sequence of amplitude values for the communication partyAmplitude cumulative distribution function ofThe inverse function of (c);
the other party of communication is according to the abnormal amplitude proportionDetermining the upper threshold value as:determining the lower threshold value as follows:(ii) a Wherein,a sequence of amplitude values for the other party of the communicationAmplitude cumulative distribution function ofThe inverse function of (c).
Wherein the amplitude anomaly ratio is 0.08.
Wherein, the communication party determines the equal probability quantization region and the sub-region of each equal probability quantization region, including:
the communication party determines the boundary of each equal probability quantization region according to the quantization bit number and the phase accumulation distribution function of the target phase value sequence so as to divide the total range of the phase values into a predetermined number of equal probability quantization regions, and each equal probability quantization region has corresponding codes; each equiprobable quantization region is equally divided into two sub-regions, each sub-region having a corresponding quantization mapping value.
Wherein, the other party of communication divides an equiprobable quantization region according to the quantization mapping value sequence, and comprises: and the other communication party determines an equiprobable quantization region boundary except the first boundary and the tail boundary according to the quantization mapping value sequence, and determines an equiprobable quantization region based on the first boundary and the tail boundary of the one communication party.
In order to achieve the above object, the present invention further provides a key extraction system based on wireless channel characteristics, wherein two communication parties of the key extraction system include a communication party and a communication party;
both communication parties are used for: determining a CFR estimation value by using a detection signal sent by the opposite side; the CFR estimation value comprises an amplitude value sequence and a phase value sequence; screening the phase value sequence according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence after screening by both communication parties;
wherein the communication party is further configured to: determining an equiprobable quantization region and a sub-region of each equiprobable quantization region, and determining an equiprobable quantization region and a sub-region in which each phase value in a target phase value sequence of the communication party falls; generating a first key according to the code of each equal probability quantization region, generating a quantization mapping value sequence according to the quantization mapping value of each sub-region, and sending the quantization mapping value sequence to the other communication party;
the other party of the communication is also used for: dividing the equal probability quantization regions according to the quantization mapping value sequence, determining the equal probability quantization region into which each phase value in the target phase value sequence of the other communication party falls, and generating a second key according to the coding of each equal probability quantization region falling.
Wherein the communication party comprises: a first region determination module;
the region determining module is used for determining the boundary of each equiprobable quantization region according to the quantization bit number so as to divide the total range of phase values into a preset number of equiprobable quantization regions, and each equiprobable quantization region has corresponding codes; each equiprobable quantization region is equally divided into two sub-regions, each sub-region having a corresponding quantization mapping value.
Wherein the other party of communication comprises: a second region determination module;
the second region determining module is configured to determine, according to the sequence of quantization mapping values, an equiprobable quantization region boundary excluding a head boundary and a tail boundary, and determine an equiprobable quantization region using the head boundary and the tail boundary of the communication party.
According to the scheme, the key extraction method based on the wireless channel characteristics provided by the embodiment of the invention comprises the following steps: both communication parties determine a CFR estimation value by using a detection signal sent by the other party; the CFR estimation value comprises an amplitude value sequence and a phase value sequence; the two communication parties screen the phase value sequence according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence screened by the two communication parties; a communication party determines an equal probability quantization area and a sub-area of each equal probability quantization area, and determines an equal probability quantization area and a sub-area in which each phase value in a target phase value sequence of the communication party falls; generating a first key according to the code of each equal probability quantization region, generating a quantization mapping value sequence according to the quantization mapping value of each sub-region, and sending the quantization mapping value sequence to the other communication party; and the other communication party divides the equal probability quantization regions according to the quantization mapping value sequence, determines the equal probability quantization region into which each phase value in the target phase value sequence of the other communication party falls, and generates a second key according to the coding of each equal probability quantization region which falls.
Therefore, the scheme utilizes the amplitude value sequence and the amplitude screening threshold value to screen the phase value sequence, so that the condition that the key inconsistency rate is higher when the amplitude of the CFR estimation value is too large or too small due to random noise or other interference and the like can be effectively avoided, and the key inconsistency rate is reduced; in addition, since the equal probability quantization region of the other communication party is determined according to the quantization mapping value sequence transmitted by the one communication party, the inconsistency rate of the keys generated by the two communication parties can be further reduced; furthermore, when the phase value sequence is screened, the phase value which is easy to quantize inconsistent key bits is deleted pertinently, so that the deleted data is less, and the generation rate of the key is improved under the condition of ensuring lower key inconsistency rate; the invention also discloses a key extraction system based on the wireless channel characteristics, and the technical effects can be realized.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a key extraction method based on wireless channel characteristics according to an embodiment of the present invention;
FIG. 2 is a comparison diagram of key inconsistency rates disclosed in an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a comparison of key generation rates disclosed in an embodiment of the present invention;
FIG. 4 is a schematic view of the overall flow of a key extraction method disclosed in the embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a comparison of key inconsistency rates at different SNR according to an embodiment of the present invention;
fig. 6 is a schematic diagram illustrating a comparison of key generation rates at different signal-to-noise ratios according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention discloses a key extraction method, a device, equipment and a storage medium based on wireless channel characteristics, which are used for improving the key generation rate while ensuring the lower key inconsistency rate.
Referring to fig. 1, an embodiment of the present invention provides a key extraction method based on wireless channel characteristics, including:
s101, both communication sides determine a CFR estimation value by using a detection signal sent by the other side; the CFR estimation value comprises an amplitude value sequence and a phase value sequence; both of the communication parties use pilot frequency information in a probe signal transmitted by the other party to determine CFR estimated values of both of the communication parties.
It can be understood that, in the scheme, both communication parties need to send probe signals to each other in sequence within coherence time and perform Channel estimation to obtain a CFR (Channel Frequency Response) estimation value; specifically, both legal communication parties in the scheme form a point-to-point Time Division duplex Orthogonal Frequency Division Multiplexing (TDD-OFDM) communication system, the two legal communication parties send channel detection signals to each other in sequence, the estimation of the CFR at the pilot Frequency position is completed by utilizing the pilot Frequency information in the received detection signals, and the estimation modulus of the CFR and the application of an inverse trigonometric function are used for respectively obtaining the amplitude value and the phase value of the CFR. Because the detection signal is composed of data bit and pilot frequency bit, the pilot frequency is a known signal of both receiving and transmitting parties specially used for channel estimation, the scheme only realizes CFR estimation for pilot frequency information, and by the mode, data transmission is not delayed when the channel is detected.
S102, the two communication parties screen the phase value sequence according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence screened by the two communication parties;
specifically, in this embodiment, an excessively large or small amplitude value may be searched from the amplitude value sequence by setting an amplitude screening threshold value, and after the phase value corresponding to the excessively large or small amplitude value is deleted, a situation that the key inconsistency rate is high when the amplitude of the CFR estimation value is excessively large or small due to random noise or other interference may be avoided, so that the key inconsistency rate is reduced. In this embodiment, the amplitude filtering threshold may be preset, or may be determined according to the obtained amplitude value sequence, which is not described herein again.
It can be understood that, in this embodiment, the two communicating parties may include one communicating party and the other communicating party, and for the above-mentioned S101 and S102, the operations that both the communicating party and the other communicating party need to perform are operations, and if the communicating party is abbreviated as Alice and the other communicating party is abbreviated as Bob, after S101 is performed, Alice and Bob both generate respective CFR estimated values, and after S102 is performed, Alice and Bob both generate respective target phase value sequences.
S103, a communication party determines an equal probability quantization area and a sub-area of each equal probability quantization area, and determines an equal probability quantization area and a sub-area in which each phase value in a target phase value sequence of the communication party falls; generating a first key according to the code of each equal probability quantization region, generating a quantization mapping value sequence according to the quantization mapping value of each sub-region, and sending the quantization mapping value sequence to the other communication party;
when it is necessary to describe, after both communication parties generate the corresponding target phase value sequence, the target phase value sequence needs to be quantized to obtain the corresponding key. When generating the key, the communication party of both parties needs to divide the equal probability quantization region and the sub-region of each equal probability quantization region. The process of determining the equal probability quantization regions and the sub-regions of each equal probability quantization region by a communication party in the scheme specifically comprises the following steps: a communication party determines the boundary of each equal probability quantization region according to the quantization bit number and the phase accumulation distribution function of the target phase value sequence so as to divide the total range of the phase values into a predetermined number of equal probability quantization regions, wherein each equal probability quantization region has corresponding codes; each equiprobable quantization region is equally divided into two sub-regions, each sub-region having a corresponding quantization mapping value.
Specifically, if the target phase value sequence of the communication party of the filtered CFR estimated value isThe target phase value sequence of the other party of communication isWherein:,and m is the number of phase values retained. One of the two communication parties is firstly according toCumulative distribution function ofOverall range of phase valuesIs divided intoQuantizing the regions with equal probability, and using different values for each region with equal probabilityThe bit Gray code is coded sequentially, with equal probability region boundary,WhereinThe number of bits quantized for each phase value; for example: setting the number of bits quantized per phase valueAlice basisCumulative distribution function ofOverall range of phase valuesIs divided intoAnd (3) quantizing the regions with equal probability, and sequentially encoding the 8 regions with equal probability into a 3-bit Gray code: 000. 001, 011, 010, 110, 111, 101, 100.
After the equal probability quantization regions are determined, each equal probability quantization region needs to be equally divided into two sub-regions, and the boundary between the two sub-regions isAnd setting different quantization mapping values for the two subintervals, such as: for the firstPhase valueQuantizing the mapped value if the value falls within the left subinterval of the quantization region(ii) a If it is notFalls within the right subinterval of the quantization region, the mapped value is quantizedNamely:
after the equal probability quantization region with the corresponding code and the sub-region with the corresponding quantization mapping value are determined in the above way, the Alice terminal can perform the filtering on the target phase value sequenceQuantizing each phase value into corresponding 3-bit Gray code according to the equivalent area in which the phase value falls, and concatenating all quantized results to obtain a first secret keySimultaneously recording the quantization mapping value generated during quantizationA sequence; that is to say: at each quantized phase valueA 3-bit Gray code and a quantized mapping value can be obtainedAlice will filter the phase value sequenceObtained after quantizationThe 3 bits Gray code are connected to obtain a length of 3 ×First key of (2)(ii) a Obtained after quantizationAnValue-joining, i.e. obtaining the length to be sent to Bob asIs/are as followsAnd (4) sequencing.
And S104, dividing the equal probability quantization regions according to the quantization mapping value sequence by the other communication party, determining the equal probability quantization region into which each phase value in the target phase value sequence of the other communication party falls, and generating a second key according to the coding of each equal probability quantization region which falls.
In this embodiment, in order to reduce the rate of inconsistency between the keys generated by both communication parties, the equal probability quantization region of Bob is adjusted according to the quantization mapping value sequence sent by Alice, and then the phase sequence of CFR is quantized by the adjusted equal probability quantization region. Specifically, the method comprises the following steps: when the other communication party divides the equal probability quantization region according to the quantization mapping value sequence, the equal probability quantization region boundary except the head boundary and the tail boundary is determined according to the quantization mapping value sequence, and the equal probability quantization region is determined based on the head boundary and the tail boundary of the communication party.
In particular toIn other words, Alice will quantize the mapped valuesThe sequence is sent over the open channel to Bob, who, based on the received sequenceAnd (3) constructing a new equal probability quantization region by the sequence, and sequentially coding each equal probability quantization region by using different 3-bit Gray codes: 000. 001, 011, 010, 110, 111, 101, 100, wherein the new equal probability quantization region has a boundary ofWherein: bob's head boundaryAnd a trailing boundaryFirst boundary with AliceAnd a trailing boundaryThe same, that is:,and for other boundaries, by formulaDetermining, wherein,it can be seen that:、、the boundary of the new equal probability quantization region divided for the Bob terminal,in order to divide the number of quantization regions,an offset generated from the sequence of quantized mapped values; if it isThen, thenOffset amount of。
Further, after Bob divides the equal probability quantization region according to the quantization mapping value sequence, Bob will pair the phase value sequence of the CFR estimation value after screening according to the new equal probability quantization regionAnd quantizing each phase value into a corresponding 3-bit Gray code according to the area in which the phase value falls, and connecting all the quantization results to obtain a second key. When it needs to be noted, due to factors such as environmental noise, a half-duplex mode of a receiver, hardware difference and the like, inconsistent bits may exist in a first secret key and a second secret key obtained after feature quantization at both ends of Alice and Bob of two communication parties, and a final secret key with consistent security can be obtained through information negotiation and privacy enhancement subsequently.
In conclusion, the method for screening the phase value sequence by using the amplitude value sequence and the amplitude screening threshold value can effectively avoid the situation that the key inconsistency rate is high when the amplitude of the CFR estimation value is too large or too small due to random noise or other interference and the like, and reduce the key inconsistency rate; in addition, since the equal probability quantization region of the other communication party is determined according to the quantization mapping value sequence transmitted by the one communication party, the inconsistency rate of the keys generated by the two communication parties can be further reduced; furthermore, when the phase value sequence is screened, the phase value which is easy to quantize inconsistent key bits is deleted pertinently, so that the deleted data is less, and the generation rate of the key is improved under the condition of ensuring the lower inconsistent rate of the key.
Based on the foregoing embodiment, in this embodiment, the process of screening the phase value sequence by the two communication parties according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence screened by the two communication parties specifically includes the following steps:
s11, the two communication parties calculate corresponding amplitude cumulative distribution functions by using the amplitude value sequence;
specifically, according to the scheme, when the phase value sequence of the CFR estimation value is screened according to the amplitude value sequence of the CFR estimation value and the phase value sequence of the CFR estimation value after screening is obtained, firstly, the amplitude value sequence of the CFR estimation value needs to be obtained for both communication partiesAndand separately calculateAndcumulative distribution function ofAnd。
s12, determining an upper threshold value and a lower threshold value of the two communication parties according to the amplitude cumulative distribution function and a preset amplitude abnormal ratio;
wherein, the communication party is according to the abnormal ratio of the preset amplitudeDetermining the upper threshold value as:determining the lower threshold value as follows:(ii) a Wherein,a sequence of amplitude values for the communication partyAmplitude cumulative distribution function ofThe inverse function of (c);
the other party of communication is according to the abnormal amplitude proportionDetermining the upper threshold value as:determining the lower threshold value as follows:(ii) a Wherein,a sequence of amplitude values for the other party of the communicationAmplitude cumulative distribution function ofThe inverse function of (c).
It should be noted that the amplitude anomaly ratio in the present embodimentIt needs to be determined according to actual conditions, and in this embodiment, a better value is selected through simulation comparison, so as to determine the amplitude screening threshold. Fig. 2 is a schematic diagram showing a comparison of key inconsistency rates disclosed in the embodiment of the present invention; fig. 3 is a schematic diagram showing a comparison of key generation rates disclosed in the embodiment of the present invention; it can be seen from the comparison of the key inconsistency rates in the case of the abnormal amplitude ratios shown in fig. 2, the abnormal amplitude ratios are comparedThe key inconsistency rate gradually decreases, howeverThe more the increase, the smaller the decrease in the key inconsistency rate. When in useThe reduction of the key inconsistency rate is significantly reduced from before. As can be seen from the comparison of the key generation rates in the situation of the values of the amplitude anomaly ratios with different magnitudes shown in fig. 3, the key generation rate also follows the amplitude anomaly ratioIs increased and gradually decreased, andthe larger the magnitude of the increase, the faster the rate of decline of the key generation rate. Comprehensively considering two indexes of the key inconsistency rate and the key generation rate, and selecting the amplitude anomaly ratioExample (b)。
S13, the communication parties detect the amplitude value sequence, if the detected amplitude value is larger than the lower threshold value and smaller than the upper threshold value, the amplitude abnormal marking value of the detected amplitude value is recorded as a first marking value, otherwise, the amplitude abnormal marking value is recorded as a second marking value, and a marking value sequence is generated;
after the amplitude screening threshold values of the two communication parties are determined, the two communication parties can respectively carry out amplitude sequence comparison on the CFR estimated values according to the upper threshold value and the lower threshold valueAnddetecting and calculating corresponding amplitude anomaly marking valuesAnd: when it comes toAmplitude value of CFR estimated valueAt the upper thresholdAnd a lower thresholdIn between, the amplitude anomaly flag value is recorded as a first flag value, otherwise, it is recorded as a second flag value, in this scheme, the first flag value may be set to 0, and the second flag value may be set to 1, that is:
and S14, the two communication parties send the generated mark value sequences to each other, the mark value sequences sent by the other parties are compared with the mark value sequences generated by the two communication parties, and if the amplitude abnormal mark values of the same target amplitude value are the second mark values, the phase value corresponding to the target amplitude value is deleted from the phase value sequence, so that the target phase value sequence screened by the two communication parties is obtained.
In this way, after both communication parties generate corresponding marker value sequences, both communication parties need to interact and compare the respective marker value sequences through the public channel, and when the amplitude abnormal marker values of the same target amplitude value are both the second marker values, for example, when both the amplitude abnormal marker values are the second marker valuesAnd isThen, both communication parties separately set the phase value of the CFR estimated value of the position corresponding to the amplitude abnormality flag valueAndand (5) deleting. Referring to fig. 4, a schematic diagram of an overall flow of a key extraction method provided in an embodiment of the present invention is shown; as can be seen from fig. 4, after both Alice and Bob perform threshold value calculation and amplitude value sequence detection, their respective marker value sequences are sent to the other party, and then phase value sequences are filtered. When both communication parties obtain the initial key, Alice needs to send the quantized mapping value sequence to Bob, and Bob can create an equiprobable quantization region through the quantized mapping value sequence and quantize the phase value sequence to obtain the initial key.
In conclusion, the amplitude value sequence of the CFR estimated value obtained by channel detection is detected, and the corresponding phase value sequence of the CFR estimated value is screened by using the detection result, so that the situation that the key inconsistency rate is high when the amplitude of the CFR estimated value is too large or too small due to random noise or other interference and the like is effectively avoided, and the inconsistency rate of the initial key is reduced. Compared with the existing characteristic quantization method, the method has the advantages that when the phase value of the CFR estimated value is screened, the phase value which is easy to quantize inconsistent key bits is deleted in a targeted mode, so that deleted data are less, and the generation rate of the key is improved under the condition that the lower initial key inconsistency rate is guaranteed.
Referring to fig. 5, a schematic diagram for comparing key inconsistency rates at different signal-to-noise ratios is provided in the embodiment of the present invention; referring to fig. 6, a schematic diagram of comparing seed key generation rates under different signal-to-noise ratios is provided in the embodiment of the present invention; it can be seen that fig. 5 and fig. 6 are respectively the comparison between the key inconsistency rate and the key generation rate under different signal-to-noise ratios of the present scheme and two existing feature quantization methods, namely, CQA and improved CQG.
In FIG. 5, the abscissa represents the signal-to-noise ratioThe ordinate represents the key inconsistency rate of both parties of legal communication, the curve with the diamond represents the key inconsistency rate obtained by the method provided by the invention, the curve with the circle represents the key inconsistency rate obtained by a CQA method, and the curve with the square represents the key inconsistency rate obtained by an improved CQG method; in FIG. 6, the abscissa represents the signal-to-noise ratioThe ordinate represents the key generation rate under the condition that the channel detection rate is unchanged, the curve with the diamond represents the key generation rate obtained by the method provided by the invention, the curve with the circle represents the key generation rate obtained by the CQA method, and the curve with the square represents the key generation rate obtained by the improved CQG method.
It can be seen that the three methodsThe key inconsistency rate of the method is gradually reduced along with the increase of the signal-to-noise ratio, and the key inconsistency rate of the scheme is the lowest, such as inCompared with CQA and improved CQG methods, the key inconsistency rate of the method is reduced by 31.5% and 20.4% respectively. In the aspect of key generation rate, the CQA method has the highest key generation rate because any CFR estimation value is not deleted; the improved CQG method has the advantages that the CFR estimated value deleted is the most, and the key generation rate is relatively the lowest; the method provided by the invention has the advantages that the CFR estimated value is deleted in a targeted manner, the deleted CFR estimated value is much less than that of an improved CQG method, and the key generation rate is obviously improved. Such as inIn time, the key generation rate of the invention is improved by 5.2 percent compared with the improved CQG method, which is between the CQA and the improved CQG method. The result shows that the scheme can remarkably improve the key generation rate while ensuring the lower key inconsistency rate.
The key extraction system provided by the embodiment of the present invention is introduced below, and the key extraction system described below and the key extraction method described above may be referred to each other.
The embodiment of the invention provides a key extraction system based on wireless channel characteristics, wherein two communication parties of the key extraction system comprise a communication party and a communication party;
both communication parties are used for: determining a CFR estimation value by using a detection signal sent by the opposite side; the CFR estimation value comprises an amplitude value sequence and a phase value sequence; screening the phase value sequence according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence after screening by both communication parties;
wherein the communication party is further configured to: determining an equiprobable quantization region and a sub-region of each equiprobable quantization region, and determining an equiprobable quantization region and a sub-region in which each phase value in a target phase value sequence of the communication party falls; generating a first key according to the code of each equal probability quantization region, generating a quantization mapping value sequence according to the quantization mapping value of each sub-region, and sending the quantization mapping value sequence to the other communication party;
the other party of the communication is also used for: dividing the equal probability quantization regions according to the quantization mapping value sequence, determining the equal probability quantization region into which each phase value in the target phase value sequence of the other communication party falls, and generating a second key according to the coding of each equal probability quantization region falling.
Wherein, the two communication parties are specifically used for: the CFR estimated value of both communication parties is determined by using pilot frequency information in a probe signal transmitted by the other party.
Wherein, the two communication parties are specifically used for: calculating a corresponding amplitude cumulative distribution function by using the amplitude value sequence; determining an upper threshold value and a lower threshold value of the two communication parties according to the amplitude cumulative distribution function and a preset amplitude abnormal ratio; detecting the amplitude value sequence, if the detected amplitude value is larger than the lower threshold value and smaller than the upper threshold value, recording an amplitude abnormal marking value of the detected amplitude value as a first marking value, otherwise, recording the amplitude abnormal marking value as a second marking value, and generating a marking value sequence;
and the two communication parties send the respectively generated mark value sequences to the other party, compare the mark value sequences sent by the other party with the mark value sequences generated by the two communication parties, and if the amplitude abnormal mark values of the same target amplitude value are the second mark values, delete the phase value corresponding to the target amplitude value from the phase value sequence to obtain the target phase value sequences screened by the two communication parties.
Wherein, the communication party is according to the preset amplitude abnormal proportionDetermining the upper threshold value as:determining the lower threshold value as follows:(ii) a Wherein,a sequence of amplitude values for the communication partyAmplitude cumulative distribution function ofThe inverse function of (c);
the other party of communication is according to the abnormal amplitude proportionDetermining the upper threshold value as:determining the lower threshold value as follows:(ii) a Wherein,a sequence of amplitude values for the other party of the communicationAmplitude cumulative distribution function ofThe inverse function of (c). The amplitude anomaly ratio was 0.08.
Wherein the communication party comprises: a first region determination module;
the region determining module is used for determining the boundary of each equiprobable quantization region according to the quantization bit number so as to divide the total range of phase values into a preset number of equiprobable quantization regions, and each equiprobable quantization region has corresponding codes; each equiprobable quantization region is equally divided into two sub-regions, each sub-region having a corresponding quantization mapping value.
Wherein the other party of communication comprises: a second region determination module;
the second region determining module is used for determining an equiprobable quantization region boundary except a head boundary and a tail boundary according to the quantization mapping value sequence and determining an equiprobable quantization region by utilizing the head boundary and the tail boundary of the communication party.
The embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the key extraction method based on wireless channel characteristics described in any of the above-mentioned method embodiments are implemented.
Wherein the storage medium may include: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A key extraction method based on wireless channel characteristics is characterized by comprising the following steps:
both communication parties determine a CFR estimation value by using a detection signal sent by the other party; the CFR estimation value comprises an amplitude value sequence and a phase value sequence;
the two communication parties screen the phase value sequence according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence screened by the two communication parties;
a communication party determines an equal probability quantization area and a sub-area of each equal probability quantization area, and determines an equal probability quantization area and a sub-area in which each phase value in a target phase value sequence of the communication party falls; generating a first key according to the code of each equal probability quantization region, generating a quantization mapping value sequence according to the quantization mapping value of each sub-region, and sending the quantization mapping value sequence to the other communication party;
and the other communication party divides the equal probability quantization regions according to the quantization mapping value sequence, determines the equal probability quantization region into which each phase value in the target phase value sequence of the other communication party falls, and generates a second key according to the coding of each equal probability quantization region which falls.
2. The key extraction method according to claim 1, wherein the determining of the CFR estimation value by the two communicating parties using a probe signal transmitted from the other party includes:
the two communication parties determine CFR estimated values of the two communication parties by using pilot frequency information in the detection signals transmitted by the other communication parties.
3. The method of claim 1, wherein the two parties of communication filter the phase value sequence according to the amplitude value sequence and the amplitude filter threshold value to obtain a filtered target phase value sequence, and the method comprises:
the two communication parties calculate corresponding amplitude cumulative distribution functions by using the amplitude value sequence;
determining an upper threshold value and a lower threshold value of the two communication parties according to the amplitude cumulative distribution function and a preset amplitude abnormal ratio;
the communication parties detect the amplitude value sequence, if the detected amplitude value is larger than the lower threshold value and smaller than the upper threshold value, the amplitude abnormal marking value of the detected amplitude value is recorded as a first marking value, otherwise, the amplitude abnormal marking value is recorded as a second marking value, and a marking value sequence is generated;
and the two communication parties send the respectively generated mark value sequences to the other party, compare the mark value sequences sent by the other party with the mark value sequences generated by the two communication parties, and if the amplitude abnormal mark values of the same target amplitude value are the second mark values, delete the phase value corresponding to the target amplitude value from the phase value sequence to obtain the target phase value sequences screened by the two communication parties.
4. The method of claim 3, wherein the determining an upper threshold and a lower threshold of the two communicating parties according to the amplitude cumulative distribution function and a preset amplitude anomaly ratio comprises:
the communication party is according to the preset amplitude abnormal proportionDetermining the upper threshold value as:
determining the lower threshold value as follows:(ii) a Wherein,a sequence of amplitude values for the communication partyAmplitude cumulative distribution function ofThe inverse function of (c);
the other party of communication is according to the abnormal amplitude proportionDetermining the upper threshold value as:
5. The key extraction method according to claim 4, wherein the amplitude anomaly ratio is 0.08.
6. The key extraction method according to any one of claims 1 to 5, wherein the determining, by the communication party, the equiprobable quantization regions and the sub-regions of each equiprobable quantization region comprises:
the communication party determines the boundary of each equal probability quantization region according to the quantization bit number and the phase accumulation distribution function of the target phase value sequence so as to divide the total range of the phase values into a predetermined number of equal probability quantization regions, and each equal probability quantization region has corresponding codes; each equiprobable quantization region is equally divided into two sub-regions, each sub-region having a corresponding quantization mapping value.
7. The key extraction method according to claim 6, wherein the dividing of the equiprobable quantization region by the other party of communication based on the sequence of quantization mapping values comprises:
and the other communication party determines an equiprobable quantization region boundary except the first boundary and the tail boundary according to the quantization mapping value sequence, and determines an equiprobable quantization region based on the first boundary and the tail boundary of the one communication party.
8. A key extraction system based on wireless channel characteristics is characterized in that two communication parties of the key extraction system comprise a communication party and a communication party;
both communication parties are used for: determining a CFR estimation value by using a detection signal sent by the opposite side; the CFR estimation value comprises an amplitude value sequence and a phase value sequence; screening the phase value sequence according to the amplitude value sequence and the amplitude screening threshold value to obtain a target phase value sequence after screening by both communication parties;
wherein the communication party is further configured to: determining an equiprobable quantization region and a sub-region of each equiprobable quantization region, and determining an equiprobable quantization region and a sub-region in which each phase value in a target phase value sequence of the communication party falls; generating a first key according to the code of each equal probability quantization region, generating a quantization mapping value sequence according to the quantization mapping value of each sub-region, and sending the quantization mapping value sequence to the other communication party;
the other party of the communication is also used for: dividing the equal probability quantization regions according to the quantization mapping value sequence, determining the equal probability quantization region into which each phase value in the target phase value sequence of the other communication party falls, and generating a second key according to the coding of each equal probability quantization region falling.
9. The key extraction system of claim 8, wherein the communication party comprises: a first region determination module;
the region determining module is used for determining the boundary of each equiprobable quantization region according to the quantization bit number so as to divide the total range of phase values into a preset number of equiprobable quantization regions, and each equiprobable quantization region has corresponding codes; each equiprobable quantization region is equally divided into two sub-regions, each sub-region having a corresponding quantization mapping value.
10. The key extraction system according to claim 9, wherein the other party of communication includes: a second region determination module;
the second region determining module is configured to determine, according to the sequence of quantization mapping values, an equiprobable quantization region boundary excluding a head boundary and a tail boundary, and determine an equiprobable quantization region using the head boundary and the tail boundary of the communication party.
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