JP2012080229A - Receiver, reception control method, and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately process a burst signal to be transmitted from an optical network unit (ONU) in a passive optical network (PON) system which includes the multiple ONUs and one optical line terminal (OLT) and applies optical communication quantum cipher communication.SOLUTION: Multiple specific transmitters applying optical communication quantum cipher communication in a communication system include: Running key generation sections for generating Running keys by using cipher keys managed by a receiver; and multiple value light generation sections for controlling multiple value level optical signals by using the Running keys, and then, transmitting the multiple value level optical signals. The receiver includes: management means for performing management by associating at least addresses of the multiple specific transmitters with common cipher keys for each specific transmitter; and a decoding processing section for selecting the cipher key used by the specific transmitter with referring to the management means on the basis of the address of the specific transmitter, which is included in transmission data, generating a Running key through the use of the selected cipher key, controlling a multiple value level threshold with respect to a reception signal through the use of the Running key, and then, acquiring decoding data on the reception signal.

Description

  The present invention relates to a receiving apparatus, a reception control method, and a communication system, and more particularly, to reception control in an OLT (Optical Line Terminal) of an uplink signal transmitted from an ONU (Optical Network Unit) in a PON (Passive Optical Network) system. .

  2. Description of the Related Art An Ethernet PON system that efficiently implements broadband IP (Internet Protocol) communication using a PON (Passive Optical Network) system type FTTH (Fiber to the Home) network has been put into practical use. In an EPON (Ethernet (registered trademark) Passive Optical Network) system, a TDM optical signal output from one OLT (Optical Line Terminal) arranged on the station side is distributed by an optical distributor to be used by a plurality of users. Provided to each ONU (Optical Network Unit).

  In the current PON system, the time division multiplexing (TDM) broadcast mode in the PON downlink is used for downlink data transmission from the OLT to the PON system, and for uplink data transmission from the ONU to the OLT, A time division multiple access (TDMA) access mode is used. In the PON uplink, an n: 1 (multipoint-to-point) burst communication mode is used instead of the conventional 1: 1 continuous communication mode.

  The upstream signal transmitted from the ONU is a burst signal based on a binary signal (optical signal), and the strength of the upstream burst signal received by the OLT is the transmission distance and the number of branches between the OLT and the ONU. It depends on the installation location and is not constant. This means that optical burst signals of various intensities reach the OLT intermittently from each ONU in a time division manner. Under such circumstances, various techniques have been proposed for processing burst signals in the OLT. For example, Patent Document 1 discloses a burst signal receiving method for improving the response to a burst signal.

  By the way, the present applicant has proposed optical communication quantum cryptography (Y-00) communication based on Yuen-2000 quantum cryptography. This communication system is a communication technique that spreads light quantum fluctuations (quantum shot noise) by modulation and makes it impossible to receive an optical signal accurately by an eavesdropper, as disclosed in Patent Document 2, for example. Application to key quantum cryptography is proposed. In this common key quantum cryptography, a binary optical signal is set as one set (referred to as a base), a plurality of M bases are prepared, and which base is used to send data is determined by a pseudo-random number according to the encryption key. Decide on. Actually, the optical M-value signal is designed so that the distance between the signals is so small that it cannot be identified due to quantum fluctuations. Therefore, the eavesdropper cannot read the data information from the received signal and can prevent eavesdropping.

JP 2010-4228 A JP 2006-303927 A

  In the PON system, the confidentiality of transmission data is an issue, and various proposals have been made for that purpose. The present inventors have considered a technical means for dramatically improving confidentiality by applying optical communication quantum cryptography communication to the PON system.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a receiving apparatus and reception control capable of greatly improving the confidentiality of transmission data by applying optical communication quantum cryptography communication to a system having a plurality of transmitting apparatuses and one receiving apparatus. It is to realize a method and a communication system.
A more specific object of the present invention is to accurately process a burst signal transmitted from an ONU in a PON system to which optical communication quantum cryptography communication is applied.

The receiving apparatus according to the present invention is preferably connected to a plurality of transmitting apparatuses to which optical communication quantum cryptography communication is applied via an optical transmission path, and transmission data controlled to a multilevel optical signal using a running key. A receiving device for receiving
A management unit that associates and manages addresses of the plurality of transmission devices and an encryption key that is common to the transmission devices; a photoelectric converter that receives and photoelectrically converts an optical signal transmitted from the transmission device; and Based on the address of the transmission device included in the transmission data, select the encryption key used by the transmission device with reference to the management unit, and generate a Running key using the selected encryption key, And a decoding processing unit that obtains decoded data of the received signal by controlling a multi-level threshold for the received signal using the Running key.

In a preferred example, in the receiving device, the decryption processing unit; a running key generation unit that generates a running key using a plurality of common encryption keys used in the transmission device;
Based on the address of the transmission device included in the transmission data, the encryption unit used by the transmission device is selected by referring to the management unit, and a running key is generated by a running key generation unit using the selected encryption key. And a decoding control unit for generating
Using the Running key generated by the Running key generation unit, the threshold value of the multilevel level for the reception data converted by the photoelectric converter is controlled, and according to the polarity of the reception data converted by the photoelectric converter To obtain decrypted data.

  In a preferred example, in the receiving apparatus, the management means includes addresses of all connected transmitting apparatuses, a plurality of transmitting apparatus types (first type) to which optical communication quantum cryptography is applied, and optical communication. The transmission device type (second type) to which the quantum cryptography communication is not applied and the transmission device of the first type have a management table for registering information related to the common encryption key bit string used by each transmission device. .

In a preferred example, in the receiving apparatus, the decoding processing unit further includes a frame detection unit that detects a LLID and a burst delimiter signal from a reception signal converted into an electrical signal by the photoelectric converter,
The decryption control unit generates a running key generation start signal and a stop signal from the detection timing and the LLID detection timing of the burst delimiter signal, and provides the running key generation unit
The Running key generation unit generates a Running key using the selected encryption key.

In a preferred example, in the receiving device, the Running key generation unit generates a Running key from the start of the Running key generation to the stop of the Running key, and generates a threshold for multilevel identification by the multilevel threshold generation unit, The polar decryption unit decrypts the polar randomization of the optical communication quantum cryptography,
Upon reception of transmission data from a transmission device that performs communication after the second time, the decryption control unit gives the LLID, the Running key generation start signal, and a stop signal to the Running key generation unit,
The running key generation unit generates a new running key from the previous running key stop position.

Preferably, the reception control method according to the present invention is connected to a plurality of transmission apparatuses to which optical communication quantum cryptography communication is applied via an optical transmission line, and is controlled to a multilevel optical signal using a running key. A reception control method for receiving data,
A management step of managing a plurality of addresses of the transmission devices in association with encryption keys common to the transmission devices;
Receiving and photoelectrically converting the received optical signal transmitted from the transmitting device; and
Selecting the encryption key used by the transmission device based on the address of the transmission device included in the transmission data, and generating a running key by a running key generation unit using the selected encryption key;
And using the generated Running key to control a multi-level threshold for the received signal to obtain decoded data of the received signal.

In a preferred example, in the reception control method, a LLID detection and a burst delimiter signal are detected by a frame detection unit from a reception signal photoelectrically converted into an electrical signal,
Generates a running key generation start signal and a stop signal from the detection timing of the burst delimiter signal and the LLID detection timing, and gives them to the running key generation unit,
The Running key generation unit generates a Running key using the selected encryption key.

In a preferred example, in the reception control method, the running key generation unit generates a running key from the start of the running key generation to the stop of the running key, and generates a threshold for multi-level identification by the multi-value threshold generation unit. The polarity decryption unit decrypts the polar randomization of the optical communication quantum cryptography,
Upon reception of transmission data from a transmission device that performs communication after the second time, the decryption control unit gives the LLID, the Running key generation start signal, and a stop signal to the Running key generation unit,
The running key generation unit generates a new running key from the previous running key stop position.

The communication system according to the present invention is preferably a communication system including a plurality of transmission devices and a reception device connected to the plurality of transmission devices via an optical transmission line.
The plurality of transmission apparatuses include a plurality of specific transmission apparatuses to which optical communication quantum cryptography is applied, and the specific transmission apparatus generates a Running key using an encryption key managed by the reception apparatus. And a multi-level light generation unit that controls a multi-level optical signal for transmission data using the Running key generated by the Running key generation unit, and is controlled by the multi-level light generation unit. Send value level optical signal,
The receiving device; at least management means for managing the addresses of the plurality of specific transmission devices in association with encryption keys common to the specific transmission devices;
A photoelectric converter that receives and photoelectrically converts the received optical signal transmitted from the specific transmission device; and
Based on the address of the specific transmission device included in the transmission data, the management unit is referred to select the encryption key used by the specific transmission device, and a running key is generated using the selected encryption key In addition, the communication system is configured to include a decoding processing unit that obtains decoded data of the received signal by controlling the threshold value of the multilevel level for the received signal using the Running key.

In a preferred example, in the communication system, the decryption processing unit; a running key generation unit that generates a running key using the common encryption key used in the specific transmission device, and the specific transmission included in the transmission data A decryption control unit that selects the encryption key used by the specific transmission device with reference to the management unit based on the address of the device, and causes the Running key generation unit to generate a Running key using the selected encryption key; Have
Using the Running key generated by the Running key generation unit, the threshold value of the multilevel level for the reception data converted by the photoelectric converter is controlled, and according to the polarity of the reception data converted by the photoelectric converter To obtain decrypted data.

In a preferred example, in the communication system, the plurality of transmission devices include a plurality of specific transmission devices to which optical communication quantum cryptography communication is applied, and a non-specific transmission device to which optical communication quantum cryptography communication is not applied,
The management means includes the address, the type of the specific transmission device (first type), the type of the non-specific transmission device (second type), and the specific transmission device for all connected transmission devices. It has a management table for registering information relating to a common encryption key bit string used by each transmission apparatus in association with each other.

  In a preferred example, in the communication system, the communication system is a PON system, the transmission device is an ONU connected to the optical transmission line via an optical distributor, and the reception device is an OLT.

According to the present invention, a receiver, a reception control method, and a communication system that greatly improve the confidentiality of transmission data by applying optical communication quantum cryptography communication to a system having a plurality of transmitters and one receiver. Can be realized.
Further, in the reception processing to which optical communication quantum cryptography communication is applied, it is possible to add a burst function to the optical communication quantum cryptography communication protocol, and it is possible to accurately process burst signals transmitted from a plurality of transmission apparatuses.

The figure which shows the outline | summary of a PON system. The figure which shows the structure of the PON system using the Y-00 quantum cryptography by one Example. The figure which shows the outline | summary of the discovery handshake operation | movement in a PON system. The block diagram which shows the structure of OLT in one Example. The figure which shows the structural example of the ONU management table in one Example. The figure which shows the structure of the Y-00 burst signal in a PON system.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of a PON system to which the present invention is applied.
The PON system includes one station side optical line terminator OLT (Optical Line Terminal) 11 and a plurality of subscriber side optical line terminators ONU (Optical Network Unit) 131 to 13m (generally indicated as 13). A transmission path and an optical distributor (also referred to as an optical splitter or a star coupler) 12 are connected to each other.
A plurality of ONUs 13 that apply Y-00 quantum cryptography (sometimes referred to as physical cryptography) communication with the OLT 11 (herein referred to as Y-00ONU) and Y-00 quantum cryptography communication are not applied. (Conventional ONU) is included. In the figure, the ONUs 133 and 13m are Y-00 ONUs, but the ONUs 131 and 132 are conventional OUNs.
In the PON system, it is necessary to manage a unique common encryption key for encryption / decryption of a packet transmitted between the OLT 11 and the Y-00ONU in which Y-00ONU and conventional ONU are mixed. Therefore, in the present invention, the OLT 11 holds a management table (described later with reference to FIG. 5).

The upstream packet P transmitted from the Y-00 ONU 13 to the OLT 11 is encrypted using the encryption key K (K1 to Kn) shared between the OLT 11 and the corresponding ONU 13, and passes through the optical distributor 12. It is sent to the optical transmission line. In the illustrated example, the packets P3 and Pm are encrypted with the encryption keys K1 and Km.
On the other hand, since the conventional ONU is not applied with Y-00 quantum cryptography communication, the upstream packet is transmitted from the ONU without being encrypted with the encryption key K. Therefore, high confidentiality of information is not ensured for packet data transmitted from the conventional ONU. Incidentally, in the conventional ONU, security is ensured by using a special algorithm at a logical level, for example, as usual.

  In the OLT 11, a packet transmitted and received from the Y-00 ONU is decrypted using a common encryption key Ki held with the corresponding ONU. Similarly, the downstream packet transmitted from the OLT 11 to the ONU 13 is encrypted using a common encryption key shared between the OLT 11 and the corresponding ONU 13 and sent to the optical transmission line 19, so that the confidentiality of the information is increased. Secured.

With reference to FIG. 3, the discovery handshake in the PON system will be described.
When the ONU 13 that has been in the offline state is newly connected to the network of the optical transmission line 19, a discovery handshake operation is executed. The OLT 11 performs processing such as confirmation of the unique address (MAC address) of the connected ONU 13, assignment of an LLID (Logical Link ID), and line delay measurement.
After this discovery handshake, the process shifts to normal data transmission (normal transmission), and Y-00 encryption transmission or non-physical encryption transmission is performed depending on the ONU type.

  FIG. 2 shows a configuration of multilevel encryption processing mainly of OLT and ONU in the PON system using Y-00 quantum cryptography. The ONUs 131 and 132 shown in FIG. 1 are conventional ONUs, and the ONUs 132 and 13m are Y-00 ONUs. (Note that Y-00ONU 133 and 13m have the same configuration, and hence the reference numeral Y-00ONU 133 will be quoted below).

  The Y-00ONU 133 responds to the value of the Running key with respect to the transmission data, the Running key generation unit 1332 that generates the Running key by inputting the encryption key K1, the transmission data generation unit 1334 that generates 1 or 0 transmission data, And a multi-level light generation unit 1333 that generates a multi-level optical signal.

The OLT 11 on the receiving side is a multi-level decoding processing unit, which receives the optical signal that has passed through the optical transmission path 19 and the optical distributor 12 and photoelectrically converts it, and a corresponding Y-00ONU (for example, 133). The receiving-side running key generation unit 112 that generates the same running key synchronized with the input of the shared encryption key K1 and the decryption processing unit 114 are configured. The decryption processing unit 114 controls the reception threshold for multi-value signal determination using the Running key generated from the Running generation unit 112 for the optical signal received by the photoelectric converter 113 to determine 1 and 0 (discrimination) To output received data. The OLT 11 holds and manages the common encryption keys K1 to Kn corresponding to the number of Y-00ONUs. (Note that FIG. 2 schematically shows the running generator 112 and the decoding processor 114, and the detailed configuration thereof is shown in FIG. 4.)
In the PON system having such a configuration, transmission data generated by the transmission data generation unit 1334 of the ONU 133 is generated as a multi-level optical signal by the multi-level optical generation unit 1333 according to the value of the Running key, and the optical distributor 12 and the optical transmission It is transmitted to the OLT 11 through the path 19.
In the OLT 11, the received optical multilevel signal is photoelectrically converted by the photoelectric converter 113. Further, a running key is generated by the running key generation unit 112 using the same encryption key K1 used when encrypted with the Y-00ONU 133. Using the Running key, the decryption processing unit 114 controls the reception threshold value to discriminate it as reception data and outputs it.

FIG. 4 shows the building blocks of the OLT.
The OLT 11 includes an upper layer 101 that performs logical encryption processing on transmission data, a MAC (Media Access Control) 102 that performs processing such as designation of a transmission destination address and transmission source address of transmission data, framing processing, and access management. , Y-00 cipher decryption processing unit 114 that performs decryption processing. Although logical encryption processing in the upper layer 101 is not directly related to the present invention, logical processing using a conventional encryption / decryption algorithm is performed.

One feature of the present invention is the management of the encryption key of each ONU 13. For this purpose, the MAC 102 has an ONU management table 50 as shown in FIG. The ONU management table 50 registers LLID, ONU address, ONU type, and ONU encryption key bit string for all m ONUs 13.
Here, the ONU type indicates whether the ONU 13 is an ONU corresponding to Y-00 quantum cryptography (Y-00 ONU) or other ONU (conventional ONU). An encryption key bit string is registered in Y-00ONU. Each Y-00 ONU has an encryption key registered in the ONU management table 50, and performs transmission data encryption processing using a Running key generated with the encryption key. Since the conventional ONU is not applied with Y-00 quantum cryptography communication, the ONU cipher key bit string is not registered.
The ONU address, ONU type, and ONU encryption key bit string are registered at the time of initial setting. Also, the LLID and ONU address are assigned by the MAC 102 associating the LLID with the ONU address during the discovery handshake.

Now, referring again to FIG. 4, the signal received at the OLT 11 is converted into an electrical signal by the photoelectric converter 113 and is decoded by the decoding processing unit 114 via the comparator 1142 of the decoding processing unit 114. Input to the processing unit. At the time of the unencrypted sync time, since a fixed potential is output from the multi-value threshold generation unit 1141, the binary signal passes through the comparator 1142 as it is.
The decryption processing unit 114 includes an ONU management table 50, a running key generation unit 112 having a running key generator that generates a plurality of n running keys based on the ONU management table 50, and a frame detection unit 52 that detects a received frame. And a decoding control unit 53 that controls decoding of the received signal, and a polarity decoding unit 54 that performs decoding according to the polarity of the received data based on the Running key generated by the Running key generation unit 112. The More specifically, the received signal converted into an electrical signal by the photoelectric converter 113 is subjected to LLID detection and burst delimiter signal detection by the frame detection unit 52 and is sent to the decoding control unit 53. The decryption control unit 53 determines the transmission source ONU from the received LLID, and acquires the ONU type by referring to the ONU management table 50.

In the case of an ONU that newly performs communication, the decryption control unit 53 outputs the LLID and the “encryption key acquisition instruction” to the running key generation unit 112. The running key generation unit 112 that has received them refers to the ONU management table 50, acquires the ONU encryption key Ki (i = 1 to n) corresponding to the LLID, and the corresponding running key in the running key generation unit 112. Set to generator Ki. The running key generator 112 has a plurality of running key generators, and one running key generator is associated with each LLID.
In addition, the decryption control unit 53 generates a Running key generation start signal and a stop signal from the detection timing and LLID detection timing of the previous burst delimiter signal, and provides them to the Running key generation unit 112.

A “running key” is generated from “running key generation start” to “running key stop” shown in FIG. 6, and a multi-value threshold generation unit 1141 generates a threshold for multi-value identification, and the decryption processing unit 114 uses a Y-00 The polar randomization is decoded.
In the case of an ONU that performs the second and subsequent communications, a LLID and a running key generation start / stop signal are input to the running key generator, and a running key is generated from the previous running key stop position.
In the Y-00 encryption decryption processing unit, an LFSR (Linear Feedback Shift Register) is generally used for the Running key generation unit 112. When the Running key is stopped, the operation of the shift register is stopped and the Running key is turned off. Holds the value of.
If the ONU type does not use Y-00 quantum cryptography (that is, the conventional ONU), no Running key is generated.

The processing of the Y-00 burst signal in FIG. 6 will be described.
Upstream transmission from Y-00ONU (for example, 133) to OLT 11 performs cryptographic transmission during normal transmission. At the sync time, there is no payload and there is no need for encryption, so a pattern similar to the sync time of the conventional PON can be used. Upstream transmission of Y-00ONU is burst reception, but it is necessary to know the timing of encryption transmission in advance at the time of reception. Therefore, after detecting a burst delimiter pattern, Y-00 encryption processing is performed after a predetermined encryption transition time. Is done.
Non-encrypted transmission is performed from an ONU not using Y-00 quantum cryptography (conventional ONU).
The Running key starts to be generated from the Y-00 encrypted data transmission start timing, and stops at the same time as the encrypted data transmission ends. Generation is restarted from the value of the Running key that was previously stopped at the next Y-00 encrypted data transmission start timing.

  The example of the PON system to which the optical communication quantum cryptography is applied has been described above. However, the present invention is not limited to the PON system, and an optical communication quantum cryptography communication system in which a plurality of transmission apparatuses and one reception apparatus are connected through an optical communication path. It is applicable to.

  As described above, according to the present embodiment, it is possible to add a burst function in the Y-00 communication protocol. In addition, a PON system in which a plurality of ONUs, in particular Y-00 ONUs to which Y-00 quantum cryptography is applied, and conventional ONUs to which it is not applied can be realized in one OLT. The user of the PON network can select the conventional optical transmission without Y-00 quantum cryptography and the optical transmission with Y-00 quantum cryptography. In particular, strong confidentiality can be ensured for data transmission using Y-00ONU.

11: OLT 12: Optical distributor 13, 131, 132, 133-13n: ONU
19: Optical transmission path K1-Kn: Encryption key P1-Pm: Packet 112: Running key generation unit 113: Photoelectric converter 114: Decryption processing unit 1332, 13m2: Running key generation unit 1333, 13m3: Multi-level light generation unit
1134, 13m4: transmission data generation unit
101: Upper layer 102: MAC
50: ONU management table 52: Frame detection unit 53: Decoding control unit
54: Polarity decoding unit 1141: Multi-value threshold generation unit 1142: Comparator.

Claims (12)

A receiving device that is connected to a plurality of transmitting devices to which optical communication quantum cryptography communication is applied via an optical transmission line and receives transmission data controlled by a multi-level optical signal using a running key,
A management means for managing a plurality of addresses of the transmission devices in association with encryption keys common to the transmission devices;
A photoelectric converter that receives and photoelectrically converts an optical signal transmitted from the transmission device; and
Based on the address of the transmission device included in the transmission data, select the encryption key used by the transmission device with reference to the management unit, and generate a Running key using the selected encryption key, A decoding processing unit that obtains decoded data of the received signal by controlling a multi-level threshold for the received signal using the Running key;
A receiving apparatus comprising: The decoding processing unit;
A running key generation unit that generates a running key using a plurality of common encryption keys used in the transmission device;
Based on the address of the transmission device included in the transmission data, the encryption unit used by the transmission device is selected by referring to the management unit, and a running key is generated by a running key generation unit using the selected encryption key. And a decoding control unit for generating
Using the Running key generated by the Running key generation unit, the threshold value of the multilevel level for the reception data converted by the photoelectric converter is controlled, and according to the polarity of the reception data converted by the photoelectric converter To obtain decrypted data,
The receiving apparatus according to claim 1. The management means includes the address, the plurality of types (first type) of the transmission device to which optical communication quantum cryptography communication is applied, and the transmission device to which optical communication quantum cryptography communication is not applied for all the transmission devices to be connected. The type (second type) and the transmission device of the first type have a management table for registering information relating to a common encryption key bit string used by each transmission device in association with each other. Or 2 receiving devices. The decoding processing unit further includes a frame detection unit that detects a LLID and a burst delimiter signal from a reception signal converted into an electric signal by the photoelectric converter,
The decryption control unit generates a running key generation start signal and a stop signal from the detection timing and the LLID detection timing of the burst delimiter signal, and provides the running key generation unit
The Running key generation unit generates a Running key using the selected encryption key;
The receiving apparatus according to claim 2. The Running key generation unit generates a Running key from the start of the Running key generation to the stop of the Running key, generates a multi-value identification threshold by the multi-value threshold generation unit, and generates an optical communication quantum cryptography by the polarity decryption unit. Decode polar randomization,
Upon reception of transmission data from a transmission device that performs communication after the second time, the decryption control unit gives the LLID, the Running key generation start signal, and a stop signal to the Running key generation unit,
The running key generation unit generates a new running key from a previous running key stop position;
The receiving device according to claim 4. A reception control method for receiving transmission data that is connected to a plurality of transmission apparatuses to which optical communication quantum cryptography communication is applied via an optical transmission line and controlled to a multilevel optical signal using a Running key,
A management step of managing a plurality of addresses of the transmission devices in association with encryption keys common to the transmission devices;
Receiving and photoelectrically converting the received optical signal transmitted from the transmitting device; and
Selecting the encryption key used by the transmission device based on the address of the transmission device included in the transmission data, and generating a running key by a running key generation unit using the selected encryption key;
Using the generated Running key to control a multilevel threshold for the received signal to obtain decoded data of the received signal;
A reception control method comprising: From the received signal photoelectrically converted into an electrical signal, the frame detector detects the LLID and the burst delimiter signal,
Generates a running key generation start signal and a stop signal from the detection timing of the burst delimiter signal and the LLID detection timing, and gives them to the running key generation unit,
Generating a running key using the selected encryption key in the running key generation unit;
The reception control method according to claim 6. The Running key generation unit generates a Running key from the start of the Running key generation to the stop of the Running key, generates a multi-value identification threshold by the multi-value threshold generation unit, and generates an optical communication quantum cryptography by the polarity decryption unit. Decode polar randomization,
Upon reception of transmission data from a transmission device that performs communication after the second time, the decryption control unit gives the LLID, the Running key generation start signal, and a stop signal to the Running key generation unit,
The running key generation unit generates a new running key from a previous running key stop position;
The reception control method according to claim 7. In a communication system including a plurality of transmission devices and a reception device connected to the plurality of transmission devices via an optical transmission path,
The plurality of transmission apparatuses include a plurality of specific transmission apparatuses to which optical communication quantum cryptography is applied, and the specific transmission apparatus generates a Running key using an encryption key managed by the reception apparatus. And a multi-level light generation unit that controls a multi-level optical signal for transmission data using the Running key generated by the Running key generation unit, and is controlled by the multi-level light generation unit. Send value level optical signal,
The receiving device;
A management unit that associates and manages at least addresses of the plurality of specific transmission devices and an encryption key common to the specific transmission devices;
A photoelectric converter that receives and photoelectrically converts the received optical signal transmitted from the specific transmission device; and
Based on the address of the specific transmission device included in the transmission data, the management unit is referred to select the encryption key used by the specific transmission device, and a running key is generated using the selected encryption key And a decoding processing unit that obtains decoded data of the received signal by controlling a threshold of a multilevel level for the received signal using the Running key. The decoding processing unit;
A running key generation unit that generates a running key using the common encryption key used in the specific transmission device;
Based on the address of the specific transmission device included in the transmission data, the management unit is referred to select the encryption key used by the specific transmission device, and the running key generation unit uses the selected encryption key. A decryption control unit for generating a Running key,
Using the Running key generated by the Running key generation unit, the threshold value of the multilevel level for the reception data converted by the photoelectric converter is controlled, and according to the polarity of the reception data converted by the photoelectric converter To obtain decrypted data,
The communication system according to claim 9. The plurality of transmission devices include a plurality of specific transmission devices to which optical communication quantum cryptography communication is applied, and a non-specific transmission device to which optical communication quantum cryptography communication is not applied,
The management means includes the address, the type of the specific transmission device (first type), the type of the non-specific transmission device (second type), and the specific transmission device for all connected transmission devices. Having a management table for registering information relating to a common encryption key bit string used by each transmission device in association with each other;
The communication system according to claim 9 or 10. The communication system is a PON system;
The transmitter is an ONU connected to the optical transmission line via an optical distributor;
The receiving device is an OLT;
The communication system according to any one of claims 9 to 11, characterized in that:

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