CN110336657B - Optical OFDM dynamic key generation method based on channel characteristics - Google Patents

Optical OFDM dynamic key generation method based on channel characteristics Download PDF

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CN110336657B
CN110336657B CN201910592164.0A CN201910592164A CN110336657B CN 110336657 B CN110336657 B CN 110336657B CN 201910592164 A CN201910592164 A CN 201910592164A CN 110336657 B CN110336657 B CN 110336657B
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binary
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吴雅婷
李春华
张倩武
李正璇
孙彦赞
王涛
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University of Shanghai for Science and Technology
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/70—Photonic quantum communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/001—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols using chaotic signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0861—Generation of secret information including derivation or calculation of cryptographic keys or passwords
    • H04L9/0869—Generation of secret information including derivation or calculation of cryptographic keys or passwords involving random numbers or seeds
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
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Abstract

The invention discloses an optical OFDM dynamic key generation method based on channel characteristics. The method comprises the following steps: (1) the two communication parties respectively generate a section of random detection signal and simultaneously send the random detection signal to the other party; (2) after receiving the detection signal in the step one, the two communication parties estimate the channel characteristics respectively; (3) the two communication parties respectively take the phase value of each subcarrier channel characteristic obtained in the step two to quantize and generate a section of binary sequence; (4) and the two communication parties carry out exclusive OR on the locally generated random detection signal, the random detection signal sent by the other party and the quantized phase binary sequence in the step three in sequence to obtain the finally required dynamic key. The method effectively utilizes the channel characteristics of both communication parties and the local private random binary signal to dynamically change the secret key, effectively improves the randomness of the secret key, can perform physical layer encryption related operation on the obtained secret key, and has strong applicability and outstanding confidentiality.

Description

Optical OFDM dynamic key generation method based on channel characteristics
Technical Field
The invention provides a channel characteristic-based optical OFDM dynamic key generation method, and provides a dynamic key generation scheme for optical OFDM physical layer encryption.
Background
With the development of high-speed data services such as IPTV, high-definition television, large-scale interactive network games, etc., the bandwidth requirement of the access network will increase sharply. In recent years, Orthogonal Frequency Division Multiplexing (OFDM) modulation has been introduced into optical fiber communication with advantages of strong dispersion resistance, high spectrum utilization rate, and the like. At the same time, it can be conveniently processed by Digital Signal Processing (DSP). In addition, the direct detection optical OFDM system (DD-OOFDM) has the advantages of simple structure, flexible dynamic bandwidth allocation, transparent heterogeneous services, good compatibility with the existing network, and the like, and thus has a great potential in the next generation optical access network. As the physical layer of optical access networks is susceptible to various attacks, the physical layer security issues become increasingly important as the capacity of users and networks increases dramatically. Previous approaches use encryption protocols to encrypt data frames, placing security issues at a higher level of the network, and thus building a security scheme based on an unsecured physical layer is risky.
Investigation of the existing documents shows that most of the existing optical OFDM physical layer encryption schemes use chaotic sequences to scramble OFDM symbol blocks in frequency domain and time domain. Document 1 Zhang L, Xin X, Liu B, et al, physical-enhanced secure in an OFDM-PON [ J ]. Optics Express,2012,20(3): 2255-. Document 2[ Sultan A, Yang X, Hajomer A A E, et al. dynamic QAM Mapping for Physical-Layer Security Using Digital channels [ J ]. IEEE Access,2018,6: 47199-. Although the research on optical OFDM physical layer encryption is more successful, the encryption schemes in the present stage all require that the two communicating parties exchange initial values of keys in advance, and once the initial values are determined, the initial values are not changed, and the whole keys are static, which reduces the security performance of the system.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the optical OFDM dynamic key generation method based on the channel characteristics, the key changes along with the channel characteristics and the random detection signals in real time, and the safety of the optical OFDM system is effectively improved.
In order to achieve the purpose, the invention is realized by the following technical scheme:
an optical OFDM dynamic key generation method based on channel characteristics, wherein the generated key is the exclusive or result of local random signals, received detection signals and quantized channel phases, comprising the following steps:
step one, a sending end A generates a random binary sequence XtAnd sending to a receiving end B; in the coherence time, B generates a random binary sequence XrSending the signal to A;
step two, the sending end A estimates the carrying signal XrThe channel response of both communication parties is obtained according to the channel characteristics of the N subcarriers:
Figure BDA0002116406890000021
wherein
Figure BDA0002116406890000022
Indicating the channel response of the ith subcarrier of the sending end A; receiver B estimates the carrying signal XtThe channel response of both communication parties is obtained according to the channel characteristics of the N subcarriers:
Figure BDA0002116406890000023
wherein
Figure BDA0002116406890000024
Indicating the channel response of the ith subcarrier of the receiving terminal B;
step three, all the transmitting terminals A
Figure BDA0002116406890000025
Quantizing to obtain binary phase sequence Pa(ii) a In the same way, the receiving end B will all
Figure BDA0002116406890000026
Obtaining a binary phase sequence P after quantizationb；
Step four, the sending end A obtains the phase quantization sequence PaAnd random binary sequence XrAnd a locally generated binary sequence XtGenerating a secret key K by performing an exclusive-or operationa(ii) a Similarly, the receiving end B will getOf the phase quantization sequence PbAnd random binary sequence XtAnd a locally generated binary sequence XrGenerating a secret key K by performing an exclusive-or operationb。
And in the first step, the random binary sequence is loaded on a data subcarrier of the OFDM in a certain modulation mode to serve as a random detection signal, wherein the length of the random sequence is consistent with the number of bits of the key.
In the third step, the phase is divided into (0,2 pi)]Are equally divided into Q sub-intervals,
Figure BDA0002116406890000027
or
Figure BDA0002116406890000028
Falling into the corresponding subinterval and carrying out corresponding binary coding, and transmitting all the signals of the transmitting end A
Figure BDA0002116406890000029
After the encoding is finished, the two sequences are combined into a binary phase sequence P in sequencea(ii) a All of receiving end B
Figure BDA00021164068900000210
After the encoding is finished, the two sequences are combined into a binary phase sequence P in sequenceb. Assuming that the length of the key to be generated is M and the number of phases to be quantized is N, Q satisfies the formula:
Figure BDA00021164068900000211
wherein
Figure BDA00021164068900000212
Represents rounding up; quantized PaAnd PbThe top M values are truncated.
Compared with the prior art, the invention has the following advantages:
the optical OFDM dynamic key generation method based on the channel characteristics, provided by the invention, has the advantages that the generated key is no longer a static key, the initial value of the key does not need to be defined by two communication parties, and the capability of the safe communication of a physical layer is effectively improved. The dynamic key provided by the invention can be automatically updated in an irregular way, and the generated key is combined with other encryption technologies, so that the difficulty of correctly decrypting the communication content by an eavesdropper is further increased, and the confidentiality is further improved compared with the prior art. The dynamic key generated by the invention is only related to the channel characteristics and random signals between two communication parties, the final keys generated by the two communication parties under the technical scheme are consistent, and the obtained key can be used for updating the initial value and parameters of the chaotic system and can be used as the key of other data encryption algorithms. The method is suitable for the dynamic key generation of the optical OFDM system and other optical communication encryption systems.
Drawings
Fig. 1 is a schematic diagram of an optical OFDM dynamic key generation process according to the present invention.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: the present example is carried out on the premise of the technical solution of the present invention, and a detailed embodiment and operation process are given, but the scope of the present invention is not limited to the following examples.
In this embodiment, the two communication parties generate 128-bit key sequences respectively in an optical OFDM system, the modulation format adopts a 16QAM scheme, the number of subcarriers is 64, the number of effective data subcarriers is 28, and the whole dynamic key generation process is as shown in fig. 1, and the specific process is as follows:
step one, a sending end A generates a random binary sequence XtAnd sent to the receiving end B. In the coherence time, B generates a random binary sequence XrAnd sending the signal to A.
Binary sequence X as described in step onet、XrThe 128-bit random binary sequence is a 128-bit random binary sequence with the same length as the required key, and in order to prevent errors in the decoding process of the receiving end, the 128-bit random binary sequence can adopt some error correction coding techniques to check and correct errors, such as parity check in the simplest form. Xt、XrAnd respectively loading the serial-parallel conversion and 16QAM modulation onto respective subcarriers.
Step two, the sending end A estimates the carrying signal XrObtaining channel responses of both communication parties according to the channel characteristics of the N sub-carriers
Figure BDA0002116406890000031
Wherein
Figure BDA0002116406890000032
Indicating the channel response of the ith subcarrier of the transmitting end); receiver B estimates the carrying signal XtObtaining channel responses of both communication parties according to the channel characteristics of the N sub-carriers
Figure BDA0002116406890000033
Wherein
Figure BDA0002116406890000034
Indicating the channel response of the ith subcarrier at the receiving end).
Step three, all the transmitting terminals A
Figure BDA0002116406890000035
Quantizing to obtain binary phase sequence Pa(ii) a In the same way, the receiving end B will all
Figure BDA0002116406890000036
Obtaining a binary phase sequence P after quantizationb. Wherein the phase interval is (0,2 pi)]Are equally divided into Q sub-intervals,
Figure BDA0002116406890000037
falling into the corresponding subinterval and carrying out corresponding binary coding, and transmitting all the signals of the transmitting end A (receiving end B)
Figure BDA0002116406890000038
After the encoding is finished, the two sequences are combined into a binary phase sequence P in sequencea(Pb)。
Q satisfies the formula:
Figure BDA0002116406890000039
where M is the entire key length (M128) and N is requiredThe number of quantized phases (since 16QAM modulation is used, it is known that the number of required effective data subcarriers N is 32), and a Q value of 16, that is, (0,2 pi) is calculated]Are equally divided into 16 subintervals ((0, pi/8)]，(π/8,π/4]，…，(15π/8,2π]) The phase quantization binary sequence corresponding to each interval is (0000,0001.., 1111).
Step four, the sending end A obtains the phase quantization sequence PaAnd random binary sequence XrAnd a locally generated binary sequence XtGenerating a secret key K by performing an exclusive-or operationa. In the same way, the receiving end B obtains the phase quantization sequence PbAnd random binary sequence XtAnd a locally generated binary sequence XrGenerating a secret key K by performing an exclusive-or operationb。
Figure BDA0002116406890000041
Figure BDA0002116406890000042
The resulting key sequences of the two legitimate parties are identical and the resulting key is related not only to the channel characteristics of the two parties, but also to the generated random binary sequence. The dynamic key characteristic of the method is characterized in that the channel characteristic changes along with the change of time, and the random sequence for the detection signal is also dynamically generated.
The generated legal key is only related to the channel and the random signal at the transmitting and receiving ends, and an eavesdropper cannot obtain the same communication channel as both the legal communication parties and cannot attack the device at the transmitting and receiving ends to obtain the random binary sequence at the legal transmitting and receiving ends, so that an attacker can hardly obtain the correct generated key, and the legal key can be changed at random time, and the encryption scheme is very safe and effective. Generated legal key KaAnd KbCan be used for updating the initial value and the parameter of the chaotic system and being used as the key of other data encryption algorithms.

Claims (4)

1. An optical OFDM dynamic key generation method based on channel characteristics, wherein the generated key is the exclusive OR result of a local random signal, a sending end signal and a quantized channel phase, and the method is characterized by comprising the following steps:
step one, a sending end A generates a random binary sequence XtAnd sending to a receiving end B; in the coherent time, the receiving end B generates a random binary sequence XrSending the data to a sending end A;
step two, the sending end A estimates the carrying signal XrThe channel response of both communication parties is obtained according to the channel characteristics of the N subcarriers:
Figure FDA0003295180190000011
where N represents the total number of subcarriers, j represents the unit of imaginary number,
Figure FDA0003295180190000012
indicating the channel phase of the i-th subcarrier of the transmitting end a,
Figure FDA0003295180190000013
indicating the channel response of the ith subcarrier of the sending end A; receiver B estimates the carrying signal XtThe channel response of both communication parties is obtained according to the channel characteristics of the N subcarriers:
Figure FDA0003295180190000014
Figure FDA0003295180190000015
where N represents the total number of subcarriers, j represents the unit of imaginary number,
Figure FDA0003295180190000016
indicating the channel phase of the ith subcarrier at the receiving end B,
Figure FDA0003295180190000017
represents the ith sub-carrier of the receiving end BA channel response of the wave;
step three, all the transmitting terminals A
Figure FDA0003295180190000018
Quantizing to obtain binary phase sequence Pa(ii) a In the same way, the receiving end B will all
Figure FDA0003295180190000019
Obtaining a binary phase sequence P after quantizationb；
Step four, the sending end A obtains the phase quantization sequence PaAnd random binary sequence XrAnd a locally generated binary sequence XtGenerating a secret key K by performing an exclusive-or operationa(ii) a In the same way, the receiving end B obtains the phase quantization sequence PbAnd random binary sequence XtAnd a locally generated binary sequence XrGenerating a secret key K by performing an exclusive-or operationb。
2. The method of claim 1, wherein the method comprises: and in the first step, the random binary sequence is loaded on a data subcarrier of the OFDM in a certain modulation mode to serve as a random detection signal, wherein the length of the random sequence is consistent with the number of bits of the key.
3. The method of claim 1, wherein the method comprises: in the third step, the phase is divided into (0,2 pi)]Are equally divided into Q sub-intervals,
Figure FDA00032951801900000110
or
Figure FDA00032951801900000111
Falling into the corresponding subinterval and carrying out corresponding binary coding, and transmitting all the signals of the transmitting end A
Figure FDA00032951801900000112
After the encoding is finished, the two sequences are combined into a binary phase sequence P in sequencea(ii) a All of receiving end B
Figure FDA00032951801900000113
After the encoding is finished, the two sequences are combined into a binary phase sequence P in sequenceb。
4. The method of claim 3, wherein the method comprises: in the third step, it is assumed that the length of the key to be generated is M, and the number of phases to be quantized is N, then Q satisfies the formula:
Figure FDA00032951801900000114
Figure FDA00032951801900000115
wherein
Figure FDA00032951801900000116
Represents rounding up; quantized PaAnd PbThe top M values are truncated.
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CN112533199A (en) * 2020-11-25 2021-03-19 南京熊猫电子股份有限公司 OFDM channel physical key generation method and device based on USRP and computer equipment
CN113179513B (en) * 2021-04-16 2022-08-09 中国人民解放军国防科技大学 Wireless channel key generation method and device based on intelligent reflector phase assistance
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