CN113422769B

CN113422769B - Transmission method based on real-time physical state of optical fiber channel and DNA coding technology

Info

Publication number: CN113422769B
Application number: CN202110686270.2A
Authority: CN
Inventors: 纪越峰; 崔嘉斌; 孔伟
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2022-03-29
Anticipated expiration: 2041-06-21
Also published as: CN113422769A

Abstract

The invention discloses a transmission method based on real-time physical state of an optical fiber channel and DNA coding technology, which is characterized in that a reverse Link is added on the basis of an optical fiber transmission Link to carry out bidirectional real-time monitoring, whether an eavesdropping phenomenon occurs or not is judged according to received signal change, a legal party and a legal party form a Link sequence real-time adjustment signal encryption mode according to four physical state information monitored by the channel in real time, and an eavesdropping party cannot know whether the encryption mode is changed or not and the change mode, so that the original signal cannot be correctly recovered. The method realizes the safety of signal transmission without changing the original transmission link format, without considering the security of an encryption key and without improving the signal encryption complexity, can realize effective resistance to attack of an eavesdropper, ensures the safety of signal transmission without the limitation of an encryption mode, speed and bandwidth in the signal transmission link, and greatly reduces the complexity of an encryption algorithm and transmission signals.

Description

Transmission method based on real-time physical state of optical fiber channel and DNA coding technology

Technical Field

The invention relates to the technical field of optical communication, in particular to a collaborative safe transmission method based on an optical fiber channel real-time physical state and a DNA coding technology.

Background

The optical communication network is the bottom layer carrier of the whole communication network, and the optical fiber is widely used due to the advantages of insulation sealing and strong anti-electromagnetic interference capability, almost more than 97 percent of the communication in the world is carried by the optical fiber, and the optical fiber is an important infrastructure for information construction. Once optical fiber has been considered to be extremely secure, but in recent years the incidents of various attacks on optical networks have been reported: in the event that a nuclear submarine in the United states intercepts an optical cable and a prism door of a Snooden exposure, a network company steals data of a user, artificially destroys and cuts an optical fiber and the like, the safety problem of the optical network is gradually concerned, and the safety performance of the whole information system is determined.

In the conventional sense, most of the security technical means for improving the optical network are focused on a Media Access Control (MAC) layer and a higher layer, and corresponding encryption and authentication protocols are adopted to perform secure data transmission. However, such high-level security techniques are often limited by the processing speed of the electronic devices and the network capacity, and are highly vulnerable and difficult to detect when transmitted over very high-rate, very long-distance optical networks. And a high-level security scheme also needs to be established on the basis of bottom-level security, algorithm encryption is easy to be stored by an eavesdropper for offline analysis, and the risk of deciphering is greatly improved. Therefore, the research on the safety performance of the physical layer of the optical network has great significance and effect.

The optical physical layer security technology is closely related to the physical characteristics of signals due to the characteristic that the optical physical layer security technology processes signals on the bottom layer, and can get rid of the bottleneck of electronic equipment processing. In recent years, research on physical layer security is mostly concentrated in the fields of quantum communication, chaotic communication and Optical Code Division Multiple Access (OCDMA), but because quantum communication is difficult to realize a single photon source and the transmission bit rate is low, chaotic communication has extremely high requirements on hardware synchronization and is greatly influenced by parameter jitter, and OCDMA greatly increases the Code word burden of a system and is easily attacked by exhaustive violence, a physical layer security scheme is urgently needed to meet the requirements of high security, high speed, long-distance transmission and compatibility with a transmission network.

DNA (deoxyribose nucleic Acid) codes integrate biotechnology and cryptography, DNA is used as an information carrier, and the natural quaternary combination of a nucleic Acid sequence is utilized for information storage and calculation, so that the method has the advantages of mass storage, low energy consumption and high parallel calculation, and is a potential novel safety technology. Many security schemes based on DNA coding techniques are proposed, but still more are used at the algorithm level and for encryption and decryption processing of information such as images and texts. For the few key scenes of safe transmission at the photophysical layer, the proposed few schemes have obvious defects of the prior art.

The signal real-time monitoring is real-time physical monitoring of the physical state of an optical network and the transmission quality of an optical signal, is substantially to measure the optical signal and extract relevant parameters for evaluating the performance of an optical communication system from the optical signal, and can reflect the real-time physical state of a transmission link, thereby providing effective guarantee for the reliability of the received signal. In conclusion, the application of the research on the DNA coding and the signal monitoring physical state in the physical layer has important significance for the safety problem of the optical network. The proposal mainly considers a cooperative safe transmission method based on the real-time physical state of the optical fiber channel and the DNA coding technology, and can effectively ensure the safety of signal transmission.

In the prior art, a transmission scheme based on DNA coding and spiral scrambling, 2. a transmission scheme based on DNA extension coding, a transmission scheme based on Software Defined Network (SDN) and Quantum Parameter Monitor (QPM), and a transmission scheme based on Quantum Alarm (QA) technology are mainly adopted.

Transmission schemes based on DNA coding and helical scrambling: the scheme realizes the encrypted transmission of signals in a physical layer in a chaotic Orthogonal Frequency-Division Multiplexing-Passive Optical Network (OFDM-PON). The scheme utilizes the biological characteristics of DNA to carry out encryption scrambling on signals, firstly converts a Pseudo-Random Binary Sequence (PRBS) into bases according to a specified DNA coding rule, then carries out base scrambling, and finally restores the scrambled bases into the Binary Sequence through the base-Binary conversion. Then the binary sequence is mapped to a Quadrature Amplitude Modulation (QAM) symbol matrix, and is traversed and rearranged into a matrix form according to the specified central position and direction. Parameters of operations such as rule selection of coding and encryption and the like are synchronized by the chaotic system. Although the scheme utilizes the DNA characteristics to carry out coding scrambling, the encryption effect is obvious, key parameters such as the encryption rule and the like of the scheme need to be synchronously determined between a transmitting party and a receiving party through the chaotic system, and the chaotic system has great limitation due to the characteristics of the chaotic system, so that once the parameters generate tiny errors, the correct decoding of the receiving end is also seriously influenced.

Transmission scheme based on DNA extension coding: the scheme realizes the encrypted transmission of signals in a physical layer in an OFDM-PON system. The scheme changes the traditional DNA coding mode depending on 2-bit binary stream, changes into coding by using 3-bit binary stream, and provides two addition operation rules corresponding to the DNA spreading code, thereby improving the randomness of the coding. In the scheme, three one-dimensional chaotic systems are adopted to carry out and control on the encryption rule. The scheme improves the traditional DNA coding mode, expands the dimension of base pairing, but the same coding rule is determined by chaotic logic mapping, has extremely high requirements on hardware and synchronization, and is difficult to ensure the correct reception of signals.

Transmission scheme [3] based on Software Defined Network (SDN) and Quantum Parameter Monitor (QPM): the scheme realizes the safe transmission of signals in a Quantum Key Distribution (QKD). An SDN application program is developed in the scheme, Quantum related parameters of Secret Key Rate (SKR) and Quantum Bit Error Rate (QBER) are monitored in real time, reaction is made under the condition that Secret Key generation is lacked or SKR and QBER values are abnormal, and a substitute route is selected for a Quantum channel. The scheme has the problems that the quantum channel is informed to switch the route once the eavesdropping condition is monitored, so that the redundancy of the channel is greatly increased, and the effective utilization rate of the channel is extremely low. Secondly, real-time monitoring is carried out through the SDN, the complexity and the operation difficulty of the system are increased, the monitoring result is only a binary state 0/1, the information obtained by monitoring is not effectively utilized, and the quality monitoring carried out by utilizing quantum signals in the QKD system has a large limitation on the transmission rate.

A transmission scheme based on Quantum Alarm (QA) technology: the scheme embeds the QKD system in a classical optical communication network to realize the safe transmission of signals. In the scheme, a quantum communication technology based on continuous variables is used in an optical fiber link for monitoring the safety of a physical layer, and the transmission link has two modes: when the quantum modulation signal is sent, the system is in a safety check mode; when transmitting data signals, the system is in a classical communication mode. After the security check mode, once the link is deemed insecure, the subsequent communication mode will be stopped and communication will be resumed using another secure link in the network. The transmission link of the scheme is divided into two modes, and the key problem lies in that the purpose of simultaneously carrying out communication and monitoring cannot be achieved, so that the utilization rate of the channel is not high, the practicability is not strong, a processing mode for the transmission process after being attacked is not given, and a subsequent effective processing mode is lacked.

In summary, the existing solutions share the following problems: the method comprises the following steps of key safety transmission problem, strict synchronization problem of system hardware, limitation of transmission rate, post-processing problem of monitoring attack, effective utilization of monitoring results and the like. Conventionally, improving the security of signal transmission only focuses on applying various encryption security measures on the transmission link, and when an illegal eavesdropper exists, the illegal eavesdropper can steal information in the transmission link during transmission and try to decrypt and recover the information. Therefore, even if the transmission information is encrypted, the key information still has the risk of being intercepted in the process that the legal sender informs the legal receiver of the encryption key and the encryption mode of the transmission information, so that the eavesdropper can simultaneously master the encrypted information and the encryption mode, the information can be recovered to a great extent, and the risk of the eavesdropping of the information is difficult to eliminate. Therefore, a cooperative secure transmission method is needed, which solves the above problems while achieving extremely secure transmission of the optical physical layer.

Disclosure of Invention

The invention aims to provide a transmission method based on a real-time physical state of an optical fiber channel and a DNA coding technology.

In order to achieve the above purpose, the invention provides the following technical scheme:

a transmission method based on real-time physical state of optical fiber channel and DNA coding technique, establishes a bidirectional transmission link between legal sender and receiver, that is, both the legal sender and receiver have a transmitter and a receiver, and both ends connect the transceiver and the link through a circulator, at this time, there are two transmission routes in the whole transmission frame, which are:

(1) information transmission: a transmitter A at a legal sender side sends data information obtained by encrypting signals by adopting a DNA coding technology, and the data information reaches a receiver B at a legal receiver side through a link to carry out normal information encryption and decryption;

(2) information monitoring: a receiver B of a legal receiver end monitors four physical states of a link in real time, a transmitter B of the legal receiver end sends a detection signal to a receiver A of the legal transmitter end through reverse link transmission in a similar way, the receiver A also monitors and records the four physical states of the reflecting link in real time, and judges whether a channel is intercepted or not;

when the legal sender side and the legal receiver side monitor the attack in real time, the legal sender side and the legal receiver side can process the physical state information obtained in real time to obtain a Link sequence, combine the Link sequence with the information encryption rule to obtain a new encryption rule, and stop transmission if the attack strength is monitored to be overlarge.

Further, the four physical states selected in the real-time monitoring are optical power P, optical signal-to-noise ratio OSNR, chromatic dispersion CD and link damage position L.

Further, the processing method for encrypting the signal by adopting the DNA coding technology in the information transmission process comprises the following steps: firstly, converting a binary sequence P1 into a base sequence S1 by a specific base complementary pairing rule to PRBS at a legal transmitter A, setting 00 and 11 in the binary sequence to be complementary and setting 01 and 10 to be complementary; then, the preset nucleotide sequences S2 and S1 of the same length are added or XOR-ed according to the nucleotide positions specified by the parameters to obtain a nucleotide sequence S3; converting the nucleotide sequence S3 into a binary sequence P2 according to the nucleotide complementary pairing rules specified by the parameters; mapping P2 into a 16QAM symbol matrix M1 through serial-parallel conversion, and performing spiral traversal on the matrix; selecting a central symbol Q in the matrix and specifying the next element and direction of traversal; after traversal, an array formed by symbols is obtained, and the symbols are rearranged into a symbol matrix M2 by rows from the first symbol of the array for subsequent transmission.

Further, the symbol matrix M1 is a 4 × 4 matrix.

Further, the next element traversed is the top, bottom, left, or right element of the previous element.

Further, the traversal direction is clockwise or counterclockwise.

Further, when the designated center symbol Q is not located at the center of the matrix, the matrix M1 is expanded by: assuming that the distances from Q to the four boundaries of the matrix are r1, r2, r3 and r4, respectively, the matrix is expanded into a matrix with Q as the center and a side length of r, wherein r is 2 × (max { r1, r2, r3, r4}) +1 by using special elements.

Further, in the process of information transmission, a 12-bit Key system Key { K0K1 … K12} is established by the transmitter a and the receiver B, and when the transmitter a codes and transmits signals according to the Key rule, the receiver B correspondingly reversely decodes according to the Key to obtain final information.

Further, the signals are monitored in real time in the information monitoring process, and the specific working process is as follows: the receiver A and the receiver B in the bidirectional link monitor the link state information in real time, and set a proper threshold value according to the attenuation abnormal degree of the selected performance pointer to divide the interception grade into two types: one is weak eavesdropping, and the other is strong eavesdropping; when the interception grade is weak interception, the legal sender side and the legal receiver side combine the four monitored and recorded physical state information Link sequences with the DNA coding rule for updating; and when the interception level is strong interception, stopping the transmission process and readjusting the link.

Further, the updating method comprises the following steps: and correspondingly quantizing according to the change range, quantizing the obtained information of each bit of physical state into a 3-bit sequence, finally forming a 12-bit Link sequence { N0N1 … N12}, and bitwise XOR-ing the Link { N0N1 … N12} and the original Key { K0K1 … K12} to obtain an updated Key sequence Key1{ F0F 1 … F12 }.

Compared with the prior art, the invention has the beneficial effects that:

the method of the invention creatively provides that a reverse Link is added on the basis of the optical fiber transmission Link so as to carry out bidirectional real-time monitoring, whether the eavesdropping phenomenon occurs can be judged according to the received signal change, the legal parties adjust the signal encryption mode in real time according to the four physical state information Link sequences monitored by the channel in real time, and the eavesdropping party cannot know whether the encryption mode is changed or not and the change mode, so that the original signal cannot be correctly recovered. The method realizes the safety of signal transmission under the conditions of not changing the original transmission link format, not considering the safety of an encryption key and not improving the complexity of signal encryption.

Meanwhile, the cooperative safe transmission method based on the real-time physical state of the optical fiber channel and the DNA coding technology carries out DNA coding on the signal at the sending end, and because the secret key, namely a specific encryption rule specified by the system, has fewer secret key bits and is convenient to change in real time. And only one bit change of the encryption key in the DNA encoding can make a large difference in signal form. Under the transmission method of real-time monitoring of four physical states of the signal, the physical state information Link sequence and the key sequence can be better combined, the security of the key does not need to be additionally considered, the limitations of information encryption on the transmission rate, the bandwidth and the like of the information can be avoided, and the method is compatible to various encryption modes.

Compared with a transmission scheme based on DNA coding and spiral scrambling, the method disclosed by the invention is separated from the setting of a chaotic system, is not limited by hardware, is compatible with a traditional communication system and ensures the security of a secret key by utilizing the physical state of a channel. Compared with a transmission scheme based on DNA coding and spiral scrambling, hardware parameters are used as keys, the key space is too small, and the keys cannot be replaced in time. The transmission method avoids the safety problem of the encryption key, directly changes the encryption mode according to the monitored physical state, and does not need to additionally consider the condition that the encryption mode is intercepted because Eve does not experience that the whole transmission channel can not obtain complete four physical state information. Therefore, the whole signal monitoring process is the basis for ensuring that the signal is not successfully intercepted by Eve, the safety of signal transmission is effectively ensured, and the DNA coding mode can be changed in real time according to the channel condition to ensure safe communication, so that the method is flexible and reliable. Compared with a transmission scheme based on a Software Defined Network (SDN) and a Quantum Parameter Monitor (QPM), the method has the advantages that an SDN monitoring channel is used in a QKD system, if abnormity occurs, a replacement route is selected, cross-layer interaction is carried out, the complexity of the system is increased, the redundancy rate of the route is high, the effective utilization rate is low, the method is concentrated on a physical layer for transmission, the signal monitoring process and the information transmission process are relatively independent, when the abnormity is monitored, a transmission link does not need to be replaced, the encryption mode is correspondingly changed according to four monitored physical state results, and the redundancy problem of the link does not exist.

Drawings

In order to more clearly illustrate the embodiments of the present application or technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings can be obtained by those skilled in the art according to the drawings.

Fig. 1 is a conceptual diagram of a transmission method based on a fiber channel real-time physical state and a DNA coding technique according to an embodiment of the present invention.

Fig. 2 is a spiral traversal process provided by the embodiment of the present invention.

Fig. 3 is a flowchart of a transmission method based on the real-time physical state of the fiber channel and the DNA coding technique according to an embodiment of the present invention.

Detailed Description

The invention designs a cooperative safe transmission method based on a real-time physical state of an optical fiber channel and a DNA coding technology, which is an innovative cooperative method provided in the field of safe transmission of a physical layer. Conventionally, improving the security of signal transmission only focuses on applying various encryption security measures on the transmission link, and when an illegal eavesdropper (Eve) exists, the eavesdropper can steal information in the transmission link during transmission and try to decrypt and recover the information. Therefore, even if the transmission information is encrypted, key information still has the risk of being intercepted in the process that a legal sender (Alice) informs a legal receiver (Bob) of the encryption key and the encryption mode of the transmission information, and Eve possibly grasps the encrypted information and the encryption mode at the same time, so that the information can be recovered to a great extent, and the risk of information interception is difficult to eliminate. The method breaks through the inherent thinking, jumps out of a single link mode, does not only pay attention to the signal transmission process, introduces the combination of a real-time monitoring process and the traditional transmission process, and realizes the safe transmission of signals by combining the real-time physical state obtained by monitoring a transmission channel with an encryption technology.

For Alice and Bob, the encrypted signals are normally transmitted through a forward transmission link, meanwhile, the Bob terminal sends detection signals to the Alice terminal through a reverse link, and at the moment, receivers of the Alice and the Bob terminal record the physical states of the signals in real time. Once eavesdropping attack occurs in a channel, transmitted signals are influenced to generate physical state change, at the moment, the receiving ends of the two parties immediately extract physical state information of the channel after monitoring abnormality, and Alice and Bob quantize and integrate the four physical state information into a physical state sequence Link according to the four physical state information obtained by channel monitoring, so that the encryption mode of the signals in a forward transmission channel is changed, and if signal attenuation is serious, transmission is stopped if a Link is seriously damaged. Therefore, Alice and Bob can cooperatively change the transmission mode according to the physical state sequence Link obtained by processing the real-time monitoring condition of the channel without being noticed, and the great safety of the signal is ensured. The four physical states selected in the real-time monitoring are Optical power P, Optical Signal to Noise Ratio (OSNR), Chromatic Dispersion (CD), and link damage position L:

(1) optical power P: the condition of a transmission line is reflected by the change of optical power in optical fiber communication, the sudden interruption of signals or the relatively mild fluctuation of the signal power caused by the influence of wiretapping on optical fiber signals is considered, the sudden power fluctuation is introduced in the process of installing a wiretapping device, and the power fluctuation is gently changed at a new level after the deployment is finished, so that the wiretapping behavior can be monitored and the real-time condition of a channel can be reflected by the change of the optical power;

(2) optical signal to noise ratio OSNR: the optical signal is damaged by auto-radiated noise in the link, resulting in a reduction in the OSNR. The OSNR can be used to characterize the transmission quality of signals, largely determines the error rate of the optical fiber communication system, and is a main factor limiting the transmission distance and transmission rate of the optical fiber communication system. It can reflect the system status and fault diagnosis when eavesdropping behavior occurs. The OSNR monitoring may be deployed in an optical fiber communication system to acquire a signal quality condition of the system, so as to perform real-time monitoring and maintenance on the system;

(3) dispersion CD: dispersion is used as a main damage parameter influencing the transmission distance and the transmission capacity of an optical fiber signal, so that pulses are widened due to inconsistent group velocity in the transmission process, and equipment at a receiving end generates larger bit errors due to signal distortion. Therefore, the monitoring estimation of the CD can reflect the condition of a transmission channel in real time, the CD distribution has distributed randomness on the whole transmission optical fiber, and the CD experienced by signals received by Eve and Bob is naturally different;

(4) link damage position L: the distance between the abnormal strain position and the transmitting end can be tested by processing the received signals, and the eavesdropping is positioned, so that the link damage position L is obtained. Both Alice and Bob position the eavesdropper Eve to estimate the link damage position L;

for Eve, it can only eavesdrop on the signal transmitted in the channel, and cannot realize real-time monitoring of the physical state of the whole transmission channel, even if the physical state information is obtained, it only goes through the signal state of a part of channels, and is completely different from the physical state information obtained by Alice and Bob, and the obtained Link sequence is naturally different. Therefore, even if the user eavesdrops all information in the channel and grasps the currently used secret key, the user cannot know whether the encryption mode is changed between Alice and Bob, whether the secret key used by the user is correct and the physical state sequence Link obtained by the complete Link, so that the original information cannot be correctly recovered.

Therefore, when the method is adopted and the unique physical state information of the complete channel is fused with the signal encryption, the effective resistance to the attack of an eavesdropper can be realized, the signal in the signal transmission link is not limited by the encryption mode, the speed and the bandwidth, the strict synchronization of system hardware is not needed, the problem of the safe transmission of the secret key is solved, the safety of the signal transmission is ensured, and the complexity of an encryption algorithm and the complexity of signal transmission are greatly reduced. The overall concept of the proposed new transmission scheme is shown in fig. 1.

The general flow of the proposed transmission scheme is: a bidirectional transmission link is established between an Alice terminal and a Bob terminal, namely, the Alice terminal and the Bob terminal are both provided with a transmitter and a receiver, and the transceiver and the link are connected through a circulator respectively at the two ends. At this time, two transmission routes exist in the whole transmission frame, which are respectively:

(1) information transmission: the Alice end transmitter A sends the data information after the DNA encryption, and the data information reaches the receiver B of the Bob end through a link to carry out normal information encryption and decryption;

(2) information monitoring: the receiver B of the Bob end monitors the four physical states of the link in real time, and similarly, the transmitter B of the Bob end sends a detection signal to the receiver A of the Alice end through reverse link transmission, and the receiver A also monitors and records the four physical states of the signal in real time to reflect the four physical states of the link and simultaneously judges whether the channel is intercepted or not.

Once Alice and Bob monitor the attack in real time, Alice and Bob process the physical state information obtained in real time to obtain a Link sequence, combine the Link sequence with the information encryption rule to obtain a new encryption rule, and stop transmission if the attack intensity is monitored to be too large. The specific principles of information transmission and signal monitoring are explained below.

In the proposal, a DNA coding technology is adopted to encrypt signals in the information transmission process, the biological characteristics of DNA are used to code and scramble the signals, and the encryption rule is easy to change at any time, so the method is suitable for the transmission method. First, the binary sequence P1 is converted into the base sequence S1 by a specific base complementary pairing rule for PRBS at an Alice transmitter A. In the biological properties of DNA, bases A and T, C are complementary to G, while in the binary sequence it can be seen that 00 is complementary to 11, 01 is complementary to 10, so the base complementary pairing rules are shown in Table 1:

TABLE 1 base complementary pairing rules

Rules

1

2

3

4

5

6

7

8

00

A

C

G

C

G

T

01

C

G

A

T

C

G

10

G

C

T

A

G

C

11

T

G

C

G

C

A

Subsequently, the nucleotide sequences S2 and S1 of the same length as previously set were subjected to addition or XOR operation according to the nucleotide positions specified by the parameters to obtain a nucleotide sequence S3, the rule of base addition or XOR is shown in tables 2 and 3:

TABLE 2 base addition rules

Rules	A	T	C	G
					A	C	G	A	T
T	G	C	T	A
					C	A	T	C	G
G	T	A	G	C

TABLE 3 base XOR rules

Rules	A	T	C	G
					A	A	T	C	G
T	T	A	G	C
					C	C	G	A	T
G	G	C	T	A

The nucleotide sequence S3 was further converted into a binary sequence P2 according to the base complementary pairing rules specified by the parameters. P2 is mapped into a serial-to-parallel conversion map into a 16QAM symbol matrix M1(4 × 4), which is traversed spirally. A central symbol Q is selected from the 4 × 4 matrix, and the next element (upper, lower, left, right) and direction (clockwise, counterclockwise) of traversal is designated, an array of symbols is obtained after traversal, and the symbols are rearranged into a symbol matrix M2 by rows from the first symbol of the array for subsequent transmission.

In this case, since the specified Q is not necessarily located at the center of the matrix, the matrix M1 needs to be extended to avoid traversing out of bounds. Assuming that the distances from Q to the four boundaries of the matrix are r1, r2, r3 and r4, respectively, the matrix is expanded into a matrix with the length of r by taking Q as the center by using special elements.

r＝2×(max{r1，r2，r3，r4})+1 (1)

Assuming that the symbol M12 in M1 is Q, r is 2 × 2+1 is 5, and the spiral traversal process is shown in fig. 2.

In the above process, the transmitter a and the receiver B establish a 12-bit Key hierarchy Key { K0K1 … K12}, as shown in table 4:

TABLE 4 Key assignment rules

Rules	Key bit
		P1→S1	K0 K1 K2
S1→S3	K3
		S3→P2	K4 K5 K6
Subscript of Q	K7 K8 K9 K10
		Direction of traversal	K11 K12

When the transmitter A encodes and transmits the signal according to the Key rule, the receiver B correspondingly reversely decodes according to the Key to obtain final information.

In this proposal, the signal monitoring process carries out real-time monitoring on the signal, and the specific working process is as follows: once an eavesdropper attacks in a transmission link, partial signals are obtained from the transmission signals in a coupling mode and are analyzed and processed, the signal transmission quality of a receiving end is obviously reduced, state information of a link is abnormal, at the moment, the receiver A and the receiver B in the bidirectional link monitor the state information of the link in real time, whether eavesdropping behaviors occur in the link or not can be judged according to the result abnormality and corresponding processing is carried out, an appropriate threshold value is set according to the attenuation abnormality degree of a selected performance pointer, and eavesdropping grades are divided into two types: one is a weak eavesdropping and one is a strong eavesdropping.

When the attenuation degree is not particularly serious, the attenuation degree is classified into weak interception, and the interception attack on the channel is not serious at the moment, so that the normal transmission and reception of signals are not influenced. At the moment, Alice and Bob update the four monitored and recorded physical state information Link sequences in combination with the DNA coding rule. After monitoring the abnormity, Alice and Bob extract four physical states in real time: the optical power P, the optical signal-to-noise ratio OSNR, the chromatic dispersion CD and the Link damage position L are correspondingly quantized according to the change range, the obtained information of each physical state is quantized into a 3-bit sequence, finally a 12-bit Link sequence { N0N1 … N12} is formed, and the Link { N0N1 … N12} and the original Key { K0K1 … K12} are subjected to bitwise XOR to obtain an updated Key sequence Key1{ F0F 1 … F12 }:

at this time, Eve cannot know whether the Key is changed and cannot obtain the physical state information Link of the complete channel, how to change the Key is not known, the original Key is used for decrypting the signal, the change of only one bit of the Key in the DNA coding can generate a difference in space, and Eve cannot restore the correct signal naturally.

When the attenuation degree is particularly serious, the attenuation degree is divided into a strong interception level, at the moment, the normal receiving of signals is seriously influenced by the interception action of Eve, and a link is not suitable for transmitting information any more, so that the transmission process needs to be stopped and the link needs to be readjusted.

Therefore, in the overall innovative transmission method in the proposal, the transmitter a and the receiver B keep normal real-time communication in the information transmission process, the receiver a and the receiver B simultaneously monitor four physical state information of a channel in the signal monitoring process in real time, when the receiver a and the receiver B detect signal abnormality through signal monitoring and eavesdrop, the transmitter a is informed of the message and the corresponding eavesdrop grade, the transmitter a determines to extract a physical state information Link sequence according to the eavesdrop grade to change an encryption mode or stop transmission, and the receiver B correspondingly and simultaneously obtains an updated encryption mode according to the extracted physical state information Link sequence to decode the information. Therefore, the whole novel transmission method can ensure the safety of transmission signals to a great extent by adjusting the transmission encryption mode in real time according to the physical state condition of the real-time link. The specific flow is shown in fig. 3.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or equivalents may be substituted for some of the technical features thereof, but such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A transmission method based on real-time physical state of optical fiber channel and DNA coding technique is characterized in that a bidirectional transmission link is established between a legal sender end and a legal receiver end, namely, the legal sender end and the legal receiver end are both provided with a transmitter and a receiver, the transmitter and the receiver are respectively connected with the link through a circulator at the two ends, at this time, two transmission routes exist in the whole transmission frame, and the two transmission routes are respectively:

(2) information monitoring: the receiver B of the legal receiver side monitors four physical states of a link in real time, the four physical states selected in the real-time monitoring are optical power P, optical signal to noise ratio OSNR, chromatic dispersion CD and link damage position L, the transmitter B of the legal receiver side sends a detection signal in a similar way, the detection signal reaches the receiver A of the legal transmitter side through reverse link transmission, the receiver A also monitors and records the four physical states of the reflecting link in real time for the signal, and simultaneously judges whether a channel is intercepted or not;

2. The transmission method based on the fiber channel real-time physical state and the DNA coding technology as claimed in claim 1, wherein the processing method for encrypting the signal by the DNA coding technology in the information transmission process comprises: firstly, converting a binary sequence P1 into a base sequence S1 by a specific base complementary pairing rule to PRBS at a legal transmitter A, setting 00 and 11 in the binary sequence to be complementary and setting 01 and 10 to be complementary; then, the preset nucleotide sequences S2 and S1 of the same length are added or XOR-ed according to the nucleotide positions specified by the parameters to obtain a nucleotide sequence S3; converting the nucleotide sequence S3 into a binary sequence P2 according to the nucleotide complementary pairing rules specified by the parameters; mapping P2 into a 16QAM symbol matrix M1 through serial-parallel conversion, and performing spiral traversal on the matrix; selecting a central symbol Q in the matrix and specifying the next element and direction of traversal; after traversal, an array formed by symbols is obtained, and the symbols are rearranged into a symbol matrix M2 by rows from the first symbol of the array for subsequent transmission.

3. The transmission method according to claim 2, wherein the symbol matrix M1 is a 4 x 4 matrix.

4. The method of claim 2, wherein the next element traversed is an element above, below, left, or right of the previous element.

5. The method of claim 2, wherein the traversal direction is clockwise or counterclockwise.

6. The method of claim 2, wherein the matrix M1 is expanded when the designated center symbol Q is not located at the center of the matrix, and the method comprises: assuming that the distances from Q to the four boundaries of the matrix are r1, r2, r3 and r4, respectively, the matrix is expanded into a matrix with Q as the center and a side length of r, wherein r is 2 × (max { r1, r2, r3, r4}) +1 by using special elements.

7. The transmission method based on the fiber channel real-time physical state and the DNA coding technology as claimed in claim 1, characterized in that, in the process of information transmission, the transmitter A and the receiver B establish a 12-bit Key system Key { K0K1 … K12}, and when the transmitter A codes and transmits signals according to the Key rule, the receiver B correspondingly decodes reversely according to the Key to obtain the final information.

8. The transmission method based on the real-time physical state of the optical fiber channel and the DNA coding technology as claimed in claim 7, wherein the signal is monitored in real time in the information monitoring process, and the specific working process is as follows: the receiver A and the receiver B in the bidirectional link monitor the link state information in real time, and set a proper threshold value according to the attenuation abnormal degree of the selected performance pointer to divide the interception grade into two types: one is weak eavesdropping, and the other is strong eavesdropping; when the interception grade is weak interception, the legal sender side and the legal receiver side combine the four monitored and recorded physical state information Link sequences with the DNA coding rule for updating; and when the interception level is strong interception, stopping the transmission process and readjusting the link.

9. The transmission method based on the fiber channel real-time physical state and DNA coding technology as claimed in claim 8, wherein the updating method is: and correspondingly quantizing according to the variation range, quantizing the obtained information of each bit of physical state into a 3-bit sequence, finally forming a 12-bit Link sequence { N0N1 … N12}, and bitwise XOR-ing the Link { N0N1 … N12} and the original Key { K0K1 … K12} to obtain an updated Key sequence Key1{ F0F 1 … F12 }.