Pon optical layer physical signature authentication method and optical network device
By utilizing the differences in the spectral characteristic curves of WDM filters to form ONU optical fingerprints in PON networks, the access security problem of PON networks is solved, and efficient and secure optical layer authentication is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FIBERHOME TELECOMMUNICATION TECHNOLOGIES CO LTD
- Filing Date
- 2023-06-13
- Publication Date
- 2026-05-29
AI Technical Summary
There are access security issues in PON networks. Unauthorized users can eavesdrop on downlink data packets, leading to privacy leaks. Furthermore, existing fingerprint feature extraction methods are computationally complex and costly.
By utilizing the differences in the spectral characteristic curves of the WDM filter inside the PON device, a unique ONU optical fingerprint is formed. Authentication is performed through the optical fingerprint, thereby achieving access security.
It simplifies computational costs, improves access security, reduces system complexity, and is not easily eavesdropped on or attacked.
Smart Images
Figure CN116723431B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of intelligent optical access network and multimodal network technology, and more specifically, relates to a PON optical layer physical signature authentication method and optical network equipment. Background Technology
[0002] PON (Passive Optical Network) technology is a one-to-many fiber optic access technology, consisting of an OLT (Optical Line Terminal) on the central office side, an ONU (Optical Network Unit) on the user side, and an ODN (Optical Distribution Network). In 2018, the number of fixed-line broadband subscribers worldwide exceeded 1 billion, and this number is expected to continue growing between 2018 and 2026. Reports indicate that by the end of September 2020, my country had 445 million FTTH (Fiber to the Home) subscribers. However, PON access security has some shortcomings.
[0003] In the downlink direction, the OLT broadcasts information to each ONU. Therefore, each ONU receives data packets sent by the OLT to all ONUs. Unauthorized users can also eavesdrop on and access downlink data packets, potentially leading to privacy and confidentiality leaks. Furthermore, the PON protocol is standardized, and the digital logic of the ONUs is known, making it vulnerable to tampering attacks by unauthorized communicators, resulting in the receiver receiving incorrect information.
[0004] Each optical layer physical device possesses its own unique signal fingerprint characteristics. To extract these device fingerprint characteristics from transmitted signals and apply them to authentication, hardware fingerprinting technology has emerged. Furthermore, to address the aforementioned challenges, some have proposed fingerprint feature extraction using channel noise models and dual-layer high- and low-frequency uniform wavelet decomposition and reconstruction methods. However, extracting the ONU's fingerprint characteristics using these methods requires complex computations, increasing system computational costs and device verification time. Summary of the Invention
[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a PON optical layer physical signature authentication scheme. This scheme utilizes the unique characteristics of each ONU due to the different factors inherent in its built-in WDM filter, forming an optical fingerprint based on these characteristics. PON optical layer physical signature and authentication are then performed based on the obtained optical fingerprint, thereby achieving PON access security.
[0006] To achieve the above objectives, according to one aspect of the present invention, a PON optical layer physical signature authentication method is provided. This method utilizes the fact that the spectral characteristic curves of the wavelength division multiplexing (WDM) optical filters inside a passive optical network (PON) device are affected by different factors during production and assembly, resulting in each ONU exhibiting unique characteristics due to the different factors of each built-in WDM filter. An optical fingerprint is formed based on these characterized ONU characteristics. PON optical layer physical signature and authentication are then performed based on the obtained optical fingerprint, thereby achieving PON access security.
[0007] In one embodiment of the present invention, the optical fingerprint refers to the optical fingerprint of the ONU, which is characterized by different ONU characteristics based on the spectral characteristic curves of the built-in WDM filter in the internal structure of different PON ONU BOSA.
[0008] In one embodiment of the present invention, the spectral characteristic curve of the WDM filter is related to the following factors:
[0009] The spectral characteristic curves of filters from different manufacturers and different batches are different;
[0010] Different cutting positions of the same batch of filters result in different spectral characteristic curves.
[0011] The angle at which the filter is installed during BOSA production can also result in different spectral characteristic curves of the filter.
[0012] In one embodiment of the present invention, in order to measure the spectral characteristic curve of the optical filter, wavelength power control and downlink wavelength tunability control are performed through the OLT PON MAC. A wavelength tunable laser is used at the optical module transmitter of the OLT to add wavelength control function: during data communication, the tunable laser is controlled within the drift range of the PON standard wavelength; when spectral characteristic testing is required, the tunable laser is controlled within the wavelength range of the spectral characteristics.
[0013] In one embodiment of the present invention, when transmitting test optical signals using a communication wavelength, the wavelength-tunable laser and wavelength power control in the OLT are first controlled. When there is downlink data transmission, the wavelength is adjusted to the flat-top range for normal communication. When there is no downlink data transmission, the OLT adjusts the wavelength to the edge of the filter, i.e., the characteristic range of the filter, for wavelength scanning. In this way, during the period when there is no downlink data transmission, the current received optical power is obtained on the ONU, and then the edge spectral hardware characteristics of the filter are obtained based on the known transmission wavelength of the OLT to form an optical fingerprint.
[0014] In one embodiment of the present invention, when optical fingerprint scanning is performed using a single probe light, two different wavelengths are used to transmit the test optical signal and the service optical signal respectively. The wavelength of the test optical signal in the OLT is adjusted so that the corresponding wavelength of the laser emitted is operated at the edge of the WDM filter. Then, the current receiving wavelength and receiving optical power are obtained on the ONU, and the obtained optical power is transmitted to the OLT through the uplink. Combined with the known transmission wavelength of the OLT, an optical fingerprint function is formed.
[0015] In one embodiment of the present invention, when obtaining optical fingerprints by performing spectral characteristic testing, several important points or commonly used wavelength points are first selected from the edge of the WDM filter as the initial wavelength position points for collecting optical fingerprints, forming an optical fingerprint function. Subsequently, optical fingerprint forming functions of the WDM filter corresponding to different wavelength position points will continue to be collected for subsequent ONU online authentication, so as to avoid the situation where the optical fingerprint of the corresponding wavelength collected when the ONU goes online does not exist in the database, causing the ONU online to fail.
[0016] In one embodiment of the present invention, the line distance transmitted by the ONU is also stored and managed as part of the optical fingerprint.
[0017] In one embodiment of the present invention, when an ONU goes offline and then comes back online, it is verified by optical fingerprint. When the optical fingerprint of the ONU matches the optical fingerprint in the database, the ONU can go online normally. Then the OLT continues to detect the optical fingerprint online by testing the wavelength of the optical signal. When the optical fingerprint of the ONU does not match the optical fingerprint in the database, the ONU is identified as an illegal ONU and its online access is not approved.
[0018] According to another aspect of the present invention, an optical network device for implementing the PON optical layer physical signature authentication method is also provided, including a WDM, an optical receiver, an optical transmitter, and a filter. A filter is disposed between the WDM and the optical transmitter. The optical transmitter is located in the transmission optical path of the filter. When the optical network device ONT transmits data uplink, the optical transmitter emits an uplink optical signal. The filter is used to transmit the uplink optical signal emitted by the optical transmitter to the WDM. The optical receiver can receive a probe optical signal or a service optical signal and can detect the power of the received probe optical signal or service optical signal.
[0019] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:
[0020] Compared with password authentication methods, the fingerprint features of this invention are not easily obtained through eavesdropping or attacks; and the fingerprint feature extraction method of this invention requires simple, low-cost, and easy-to-implement hardware. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the spectral characteristics of the built-in WDM filter provided by the present invention;
[0022] Figure 2 This is a schematic diagram of the system structure for optical fingerprint scanning using communication wavelengths provided by the present invention;
[0023] Figure 3 This is a schematic diagram of the system structure for optical fingerprint scanning using a separate probe light provided by the present invention;
[0024] Figure 4 This is a schematic diagram of the system structure provided by the present invention, which uses separate probe light and filter for optical fingerprint scanning;
[0025] Figure 5 This is a flowchart of the optical fingerprint scanning using communication wavelengths according to the present invention. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0027] Optical fingerprints primarily arise from the different physical characteristics of hardware in different devices of the same type within an optical network. The hardware fingerprint manifests in the device's impact on the signal. Due to slight differences between individual devices at the time of manufacture, their impact on the signal varies slightly. This difference can represent the device's identity, thus enabling device authentication based on hardware fingerprints. Besides the optical filter characteristics used in this patent, other possible optical fingerprints can be derived from laser physical characteristics, encoder physical characteristics in the optical path, etc. This patent uses the characteristics of an optical filter; the aforementioned "laser physical characteristics" and "encoder physical characteristics in the optical path" refer to other possible methods, but this patent does not employ these additional characteristics.
[0028] This invention considers that the spectral characteristic curves of the WDM (Wavelength Division Multiplexing) optical filters inside PON (Passive Optical Network) devices are affected by various factors, resulting in each ONU (Optical Network Unit) exhibiting unique characteristics due to the different factors of its built-in WDM filters. An optical fingerprint can be formed based on these characterized ONU characteristics. Using this optical fingerprint, PON optical layer physical signature and authentication are performed, thereby achieving PON access security.
[0029] The solution of this invention can be used in both traditional and future PON networks, and can be implemented without modifying the hardware of already deployed ONUs; it can be implemented simply by updating the optical modules of the OLT and the software of both the OLT and ONUs. In future PON deployments, the randomness of related optical components can be further increased during the ONU manufacturing process, making the fingerprint more obvious. In addition to authentication, wavelength characteristics can also be used as keys for encryption.
[0030] In existing PON systems, this invention utilizes the spectral characteristics of the built-in WDM filter (i.e., the filter at the ONU) within the internal structure of the BOSA (Bi-Directional Optical Sub Assemble) optical device in different PON ONUs. These characteristics can be characterized as "optical fingerprints" of the ONUs. Based on the extracted optical fingerprints, feature value fingerprints can be compared to achieve PON optical layer authentication.
[0031] The spectral characteristic curve of WDM optical filters is related to the following factors: 1. Spectral characteristic curves differ between filters from different manufacturers and batches; 2. Different cutting positions of filters within the same batch result in different spectral characteristic curves; 3. Different installation angles of filters during BOSA production also lead to different spectral characteristic curves. Newly manufactured ONUs can be appropriately adjusted based on the factors affecting the spectral characteristic curve of WDM filters, thereby making the optical fingerprint features of the manufactured ONUs more obvious and easily distinguishable, improving the accuracy of identification.
[0032] However, when a PON system is operating normally, the wavelength will only drift within the flat-top range of the filter, i.e., the drift range of the PON standard wavelength. The spectral characteristics of the filter are not noticeably affected. Figure 1 The diagram shows the relationship between the transmittance of the filter and the wavelength. However, if the wavelength operates at the edge of the filter, it will affect high-speed data transmission in normal communication.
[0033] To measure the spectral characteristic curve of the ONU optical filter online, this invention uses the MAC of the OLT PON for wavelength power control and downlink wavelength tunability control. A wavelength-tunable laser (such as...) is used at the OLT optical module transmitter. Figure 2 This is used to add wavelength control functionality. During data communication, it controls the tunable laser within the drift range of the PON standard wavelength; when spectral characteristic testing is required, it controls the tunable laser within the drift range of the filter's spectral characteristic wavelength.
[0034] In the embodiments of this invention, a common ONT can be used, such as Figure 2 and Figure 3 This utilizes the spectral characteristics of an existing single-fiber bidirectional filter. Alternatively, a new type of ONT, such as... Figure 4 As shown. The ONT includes an optical receiver 1, an optical receiver 2, an optical transmitter, a filter 1, and a filter 2. The downlink light includes service light and probe light. The filter 1 first filters the probe light down to the optical receiver 1; then the light goes to the filter 2, where the service light is filtered down to the optical receiver 2. The optical receiver 1 processes the optical power corresponding to the spectral fingerprint of the filter 1, and the optical receiver processes the data service. The two do not interfere with each other.
[0035] Specifically, in this invention, when optical fingerprint scanning is performed using a communication wavelength, that is, when transmitting service optical signals and test optical signals using a single wavelength (e.g.) Figure 2 First, by controlling the wavelength-tunable laser and wavelength power control in the OLT, when there is downlink data transmission, the wavelength is adjusted to the flat-top range for normal communication. When there is no downlink data transmission, the wavelength is adjusted to the edge of the filter, i.e., the filter's characteristic range, for operation (i.e.,...). Figure 1 (The diagonal stripe section can be either left or right). During periods of no downlink data transmission, spectral characteristic tests can be performed on the ONU to obtain the current received optical power and, based on the known transmission wavelength of the OLT, to obtain the edge hardware characteristics of the filter to form an optical fingerprint.
[0036] Tunable lasers are typically implemented using current control technology, which mainly achieves wavelength tuning by changing the injection current. They have a tuning rate in the nanosecond range and a wide tuning bandwidth.
[0037] exist Figure 2In the OLT and ONU, the WDM (Wireless Filter Media) is a filter that enables bidirectional transmission over a single fiber. Different ONUs use WDM filters with different spectral characteristics. During normal data communication, the downlink wavelength (TX) of the OLT is within the drift range of the PON wavelength. Because this is in the flat region of the filter, the optical power corresponding to the RX of the ONU is a nearly constant value, only related to the optical power of the tunable wavelength TX. When the OLT PON MAC schedules downlink communication to a point where there is no data transmission, the tunable wavelength is adjusted to within the wavelength range of its spectral characteristics. Figure 1 The diagonal stripe section (either left or right) is affected by the characteristics of the filter. The optical power corresponding to the ONU's RX is related not only to the optical power of the adjustable wavelength TX, but also to the wavelength and the filter itself. After successful connection, under the control of the PONMAC, when there is no downlink data, the wavelength is adjusted to a point characterizing the optical layer's properties. Figure 1 (For the diagonal stripe section, either left or right is acceptable). Adjust the downlink wavelength emitted by the OLT to a specific value of λ. OLT And simultaneously, the transmission power is adjusted to a suitable specific value P by the wavelength power controller. OLT Transmission is then performed. After adjusting the values at the OLT transmitter, the arriving optical power value P can be obtained from the specific ONU connected to the OLT. ONU The wavelength reaching the ONU is λ ONU The received optical power value is then reported to the OLT via the uplink. Let the optical fingerprint function of ONU_1 be f1(), the optical fingerprint function of ONU_2 be f2(), and the optical fingerprint function of ONU_n be fn(). Then, the received optical power Ponu_n during the optical fingerprint test of ONU_n is = fn(Pin_n, ONU (), where Pin_n is the optical power reaching the PON port of ONU_n, and Ponu_n is the optical power reaching the optical receiver after passing through the filter at Pin_n. The attenuation of light in the PON fiber optic channel is fixed, i.e., Pout_n = P OLT -ΔPn, for each ONU, ΔPn is a constant value that can be calculated, while the wavelength remains unchanged. In this case, the output wavelength of the OLT is: λ OLT = w(Iw), where fw() is the wavelength adjustment function and Iw is the wavelength control current. Furthermore, the output power of the OLT can be expressed as: P OLT =p(Ip), where Ip is the power control current.
[0038] The OLT can acquire optical power data reported by the ONU via the uplink and save the acquired data. This data contains characteristics of the specific ONU, mainly including the different received optical power of the ONU at different wavelengths transmitted by the OLT and their interrelationships, as well as the spectral characteristics of the filter. Therefore, it can be used as the characteristic value of the ONU. By repeatedly scheduling the OLT, more characteristic values of the current ONU can be obtained. When the number of characteristic values obtained through scheduling is large enough, the transmit wavelength, receive wavelength, and characteristic values are saved as the optical fingerprint of the current ONU. Let the optical fingerprint function of ONU1 be f1(), the optical fingerprint function of ONU2 be f2(), and the optical fingerprint function of ONUUn be f n (). The OLT stores each f that needs to be authenticated. n (), which stands for "optical fingerprint". When the OLT needs to send a string of data x that needs to be encrypted, it can use f n () is a function that encrypts x, since P here OLT , λ OLT and P ONU It's a many-to-one relationship, so random numbers can be introduced for calculations, using the same encrypted P each time. OLT , λ OLT The different values increase the difficulty of cracking the line.
[0039] When conducting spectral characteristic tests and acquiring optical fingerprints, several important points or commonly used wavelength points are first selected from the edge of the WDM filter as the initial wavelength location points for collecting optical fingerprints, forming an optical fingerprint function. Subsequently, optical fingerprint functions corresponding to different wavelength location points of the WDM filter are collected for later ONU online authentication, to avoid situations where the optical fingerprint for the corresponding wavelength is not found in the database, causing ONU online failure.
[0040] It is worth considering storing and managing the line distance transmitted by the ONU as part of the optical fingerprint.
[0041] When an ONU goes offline and then comes back online, it can be verified using optical fingerprinting. If the ONU's optical fingerprint matches the one in the database, the ONU can come online normally, and the OLT continues to detect the optical fingerprint online by testing the wavelength of the optical signal. If the ONU's optical fingerprint does not match the one in the database, the ONU is considered an illegal ONU and its online access is denied.
[0042] Specifically, its implementation process is as follows: Figure 5 It includes the following steps:
[0043] S1: At the OLT end, when there is no downlink data transmission, the OLT PON MAC is first scheduled and the specific ONU is notified in advance through the downlink.
[0044] S2: The downlink wavelength and optical power are adjusted to a specific value by using a wavelength-tunable laser and a wavelength power controller to regulate the transmission of the optical module on the OLT.
[0045] S3: Read the received optical power value on a specific ONU and report the value.
[0046] S4: The OLT PON MAC schedules downlink data transmission, and the OLT obtains the optical power data of the specific ONU reported, and saves the wavelength optical power.
[0047] S5: By repeatedly scheduling the OLT, more ONU feature values can be obtained. When a certain number of feature values are reached, the obtained wavelength and optical power data can be saved to form the optical fingerprint of a specific ONU.
[0048] S6: If an ONU goes offline and wants to come back online, an optical fingerprint comparison is required. If the optical fingerprint of the ONU wanting to come online matches the stored optical fingerprint, the ONU is allowed to come online, and online monitoring of optical fingerprints continues. If the optical fingerprint of the ONU wanting to come online does not match the stored optical fingerprint, it is considered an illegal ONU and is not allowed to come online.
[0049] Furthermore, the present invention also provides an optical network device for implementing the above-mentioned PON optical layer physical signature authentication method, including a WDM, an optical receiver, an optical transmitter, and a filter. A filter is disposed between the WDM and the optical transmitter. The optical transmitter is located in the transmission optical path of the filter. When the optical network device ONT transmits data uplink, the optical transmitter emits an uplink optical signal. The filter is used to transmit the uplink optical signal emitted by the optical transmitter to the WDM. The optical receiver can receive probe optical signals or service optical signals and can detect the power of the received probe optical signals or service optical signals.
[0050] Furthermore, in this invention, when using a separate probe light for optical fingerprint scanning, two different wavelengths are used to transmit the test optical signal and the service optical signal respectively (e.g., Figure 3 The test optical signal wavelength in the OLT is adjusted so that the tunable laser emits a wavelength corresponding to the edge of the WDM filter. Then, spectral characteristics are tested on the ONU to obtain the current received wavelength and received optical power. The obtained optical power is then transmitted back to the OLT via the uplink. Combined with the known transmitted wavelength of the OLT, an optical fingerprint function is formed. The advantage of using a separate probe light is that optical fingerprint detection can be performed even when there is downlink traffic data. However, an additional tunable laser is required at the OLT, and the optical power of the traffic light needs to be subtracted during calculation.
[0051] To minimize the impact on the data being transmitted, in addition to using two different wavelengths for the transmission of test optical signals and service optical signals respectively, new filters and receivers can be added (such as...). Figure 4 ), filter 1 is used to generate optical fingerprint, and receiver 1 is used to detect optical fingerprint. The detection light emitted by the tunable wavelength TX laser is distributed to optical receiver 1 at filter 1 and will not reach optical receiver 2 through filter 2, thereby reducing the interference of fingerprint detection on the service light of ongoing communication.
[0052] It should be noted that, Figure 2 To transmit both service optical signals and test optical signals using a single wavelength, and using an existing ONU, the transmitter of the OLT optical module needs to be modified to be adjustable. Figure 3 The test optical signal and the service optical signal are transmitted using two different wavelengths respectively. The existing ONU is also used, and an adjustable transmitter needs to be added to the OLT optical module. Figure 4 To achieve the relevant functions by adding new filters and receivers, a new ONU is required, and an adjustable transmitter also needs to be added to the OLT optical module.
[0053] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A PON optical layer physical signature authentication method, characterized in that, The spectral characteristic curves of the wavelength division multiplexing (WDM) optical filters inside passive optical network (PON) devices are affected by various factors during production and assembly, resulting in each ONU exhibiting unique characteristics due to the different factors of its built-in WDM filters. These unique ONU characteristics form an optical fingerprint. PON optical layer physical signature and authentication are then performed based on the obtained optical fingerprint, thereby achieving PON access security. The optical fingerprint refers to the different ONU characteristics characterized by the spectral characteristic curves of the built-in WDM filters in the internal structure of different PON ONUs (BOSAs), thus becoming the ONU's optical fingerprint. To measure the spectral characteristic curve of the optical filter, wavelength power and downlink wavelength tunability are controlled via the OLT PON MAC. A wavelength-tunable laser is used at the optical module transmitter of the OLT to add wavelength control functionality: during data communication, the tunable laser is controlled within the drift range of the PON standard wavelength; when spectral characteristic testing is required, the tunable laser is controlled within the wavelength range of the spectral characteristics. When using communication wavelengths to transmit test optical signals, the wavelength-tunable laser and wavelength power control in the OLT are first controlled. When there is downlink data transmission, the wavelength is adjusted to the flat-top range for normal communication. When there is no downlink data transmission, the OLT adjusts the wavelength to the edge of the filter, i.e., the characteristic range of the filter, for wavelength scanning. In this way, during the period when there is no downlink data transmission, the current received optical power is obtained on the ONU, and then the edge spectral hardware characteristics of the filter are obtained based on the known transmission wavelength of the OLT to form an optical fingerprint. When using a separate probe light for optical fingerprint scanning, two different wavelengths are used to transmit the test optical signal and the service optical signal respectively. The wavelength of the test optical signal in the OLT is adjusted so that the corresponding wavelength of the laser emitted is operated at the edge of the WDM filter. Then, the current received wavelength and received optical power are obtained on the ONU, and the obtained optical power is transmitted to the OLT through the uplink. Combined with the known transmission wavelength of the OLT, an optical fingerprint function is formed.
2. The PON optical layer physical signature authentication method as described in claim 1, characterized in that, The spectral characteristics of a WDM filter are related to the following factors: The spectral characteristic curves of filters from different manufacturers and different batches are different; Different cutting positions of the same batch of filters result in different spectral characteristic curves. The angle at which the filter is installed during BOSA production can also result in different spectral characteristic curves of the filter.
3. The PON optical layer physical signature authentication method as described in claim 1, characterized in that, When obtaining optical fingerprints through spectral characteristic testing, several important points or commonly used wavelength points are first selected from the edge of the WDM filter as the initial wavelength position points for collecting optical fingerprints, forming an optical fingerprint function. Subsequently, optical fingerprint functions corresponding to different wavelength position points of the WDM filter will continue to be collected for subsequent ONU online authentication, in order to avoid the situation where the optical fingerprint of the corresponding wavelength collected when the ONU goes online does not exist in the database, causing the ONU to fail to go online.
4. The PON optical layer physical signature authentication method as described in claim 1, characterized in that, The line distance transmitted by the ONU is also stored and managed as part of the optical fingerprint.
5. The PON optical layer physical signature authentication method as described in claim 1, characterized in that, When an ONU goes offline and then comes back online, it is verified by optical fingerprint. When the ONU's optical fingerprint matches the optical fingerprint in the database, the ONU can go online normally. Then the OLT continues to detect the optical fingerprint online by testing the wavelength of the optical signal. When the ONU's optical fingerprint does not match the optical fingerprint in the database, the ONU is identified as an illegal ONU and its online access is not approved.
6. An optical network device for implementing the PON optical layer physical signature authentication method as described in any one of claims 1-5, characterized in that, It includes a WDM, an optical receiver, an optical transmitter, and a filter. A filter is placed between the WDM and the optical transmitter. The optical transmitter is located in the transmission optical path of the filter. The optical transmitter emits an uplink optical signal when the optical network device (ONT) sends uplink data. The filter is used to transmit the uplink optical signal emitted by the optical transmitter to the WDM. The optical receiver can receive probe optical signals or service optical signals and can detect the power of the received probe optical signals or service optical signals.