JP2016032256A - Optical transmitter, optical repeater, optical receiver, optical communication system, and optical communication method - Google Patents

Abstract

Encryption communication using a Y-00 protocol can be applied to an all-optical network.
A second pseudo-random number generation unit that generates a second Running key, a key selection unit that selects a second Running key based on timing information, and destination information generated by a transmission data generation unit A binary data having a header information management part and a data part including the input, and a randomizing part for encrypting the data part based on the second Running key, and on the basis of the selected second Running key An intensity modulation unit that multi-value modulates the light intensity of the carrier wave generated by the carrier wave generation unit and transmits the encrypted data.
[Selection] Figure 8

Description

  The present invention relates to an optical transmitter, an optical repeater, an optical receiver, an optical communication system, and an optical communication method, and more particularly to routing control in optical communication quantum cryptography using multilevel intensity modulation.

  In optical communication quantum cryptography, light fluctuation (quantum shot noise) is diffused by modulation, and an optical signal cannot be accurately identified by an eavesdropper. Common key quantum cryptography is known that makes it impossible. This common key quantum cryptography is called a base, and M binary optical signals carrying transmission data are prepared as one set, and which base is used to transmit data is a pseudo-random number according to the encryption key. It is a method that decides irregularly by. Actually, the data is identified from the encrypted signal received by an eavesdropper by reducing the distance between the M-value signals with respect to the time direction of the phase and frequency by quantum fluctuation of a plurality of M values of light. The data is not decrypted (decryption is correctly established).

  Encryption based on the above principle is called Yuen quantum cryptography based on Yuen-2000 cryptographic communication protocol (abbreviated as Y-00 protocol). For example, in Patent Document 1, the security against data decryption of optical communication quantum cryptography is further enhanced. In addition, wiretapping of encryption by multi-value intensity modulation is prevented.

JP 2010-114662 A

  However, in the current cryptographic communication system using the Y-00 protocol, including the optical transmission device described in Patent Document 1, it is premised on a connection with a one-to-one dedicated line, and information necessary for routing control. Is also encrypted. For this reason, there is a problem that routing control cannot be performed when an optical signal according to the Y-00 protocol is transmitted and received in the all-optical network.

  The present invention has been made in view of the above, and is an optical transmission device, an optical relay device, an optical reception device, an optical communication system, and an optical communication device that can apply cryptographic communication using the Y-00 protocol to an all-optical network. An object is to provide an optical communication method.

  In order to solve the above-described problems and achieve the object, an optical transmission apparatus according to the present invention is an optical transmission apparatus that modulates data into an optical signal and transmits it using optical communication quantum cryptography based on multilevel intensity modulation. A second pseudo-random number generation unit that generates a second Running key, a key selection unit that selects the second Running key based on timing information, and destination information generated by the transmission data generation unit A binary data having a header information management unit and a data unit including the random number unit that encrypts the data unit based on a second Running key, and the selected second Running key. And an intensity modulation unit that multi-level modulates the optical intensity of the carrier wave generated by the carrier wave generation unit and transmits the encrypted data. It is.

  An optical repeater according to the present invention is an optical repeater that relays data transmitted by modulating an optical signal from an optical transmitter using an optical communication quantum cryptography based on multilevel intensity modulation. A signal determination unit that binarizes multi-level modulation data whose data portion is encrypted with a second Running key received from the apparatus based on a predetermined threshold, and a header included in the binarized multi-level modulation data A detection unit that detects destination information held in an information management unit, and an optical switch unit that transmits the data to another optical relay device or an optical reception device according to the detected destination information. Is configured as an optical repeater.

  An optical receiving apparatus according to the present invention is an optical receiving apparatus that receives data transmitted by modulating an optical signal from an optical transmitting apparatus using optical communication quantum cryptography based on multilevel intensity modulation. A second pseudo-random number generator for generating a running key, a key selector for selecting the second running key based on timing information, and a second running key received from the optical transmitter or the relay device A signal determination unit that binarizes the data part included in the multi-value modulation data in which the data part is encrypted based on the second Running key, and the data part is decrypted based on the second Running key. And a reconstructing unit.

  The present invention can also be understood as an optical communication system having the above-described optical transmission device, optical repeater, and optical receiver. Furthermore, the present invention is grasped as an optical communication method performed in the optical communication system.

  According to the present invention, encrypted communication using the Y-00 protocol can be applied to an all-optical network.

1 is a diagram illustrating a configuration example of an optical communication system (first embodiment). (Example 1) which is a figure which shows the structural example of the flame | frame transmitted / received. FIG. 2 is a block diagram illustrating a functional configuration of the Y-00 transmission device illustrated in FIG. 1 (Example 1). FIG. 3 is a block diagram illustrating a functional configuration of a Y-00 relay apparatus 200 (Example 1). FIG. 3 is a block diagram illustrating a functional configuration of a Y-00 receiver 300 (Example 1). (Example 2) which is a figure which shows the structural example of an optical communication system. (Example 2) which is a figure which shows the structural example of the flame | frame transmitted / received. (Example 2) which is a block diagram which shows the functional structure of the Y-00 transmission apparatus shown in FIG. It is a block diagram which shows the functional structure of the Y-00 relay apparatus 700 (Example 2). (Example 2) which is a block diagram which shows the functional structure of the Y-00 receiver 800.

  Exemplary embodiments of an optical transmitter, an optical repeater, an optical receiver, an optical communication system, and an optical communication method according to the present invention will be described below in detail with reference to the accompanying drawings.

Example 1
FIG. 1 is a diagram illustrating a configuration example of an optical communication system according to the present embodiment. As illustrated in FIG. 1, the optical communication system according to the first embodiment includes a Y-00 transmission device 100 that is a transmission side of an optical communication device, a Y-00 reception device 300 that is a reception side of an optical communication device, and Y-00. One or a plurality of Y-00 relay apparatuses 200 that relay communication with the transmission apparatus 100 and the Y-00 reception apparatus 300 described above are connected by an optical network N. In the following description, the Y-00 transmission device 100 and the Y-00 reception device 300 are described as different configurations in which the functions on the transmission side and the reception side are separated, but are configured as one device having these functions. May be.

  In this system, data (frame) transmitted and received between the Y-00 transmitting apparatus 100 and the Y-00 receiving apparatus 300 is encrypted with two types of common keys. Specifically, as shown in FIG. 1, in the frame to be transmitted / received, it is necessary for routing in the optical network in the frame using the first Running key generated from the first initial key which is the first common key. The header management information part, which is an area where various information is stored, is encrypted and decrypted. Further, using the second Running key generated from the second initial key that is the second common key, the payload portion in which the data that is originally desired to be transmitted is stored in the frame is encrypted and decrypted. In this way, in the middle of the optical communication path, the relay device decrypts and reads the destination information included in the header management information portion encrypted with the first Running key by the transmission device using the same first Running key, and relays the frame. To do. Then, the Y-00 encryption communication can be applied to the all-optical network when the receiving device decrypts and reads the data included in the payload portion encrypted with the second Running key by the transmitting device using the same second Running key. .

  FIG. 2 is a diagram illustrating a configuration example of frames transmitted and received in the present system. As shown in FIG. 2, a frame transmitted / received in this system includes a header management information part including destination information and a payload part including data. The header management information part of the frame stores a header signal indicating the start position of the header management information part and destination information indicating the transmission destination of the frame. In addition, data to be transmitted to the transmission destination is stored in the payload portion of the frame.

  FIG. 3 is a block diagram showing a functional configuration of the Y-00 transmission apparatus 100 shown in FIG. As shown in FIG. 3, the Y-00 transmission apparatus 100 includes a pseudo random number generation unit 101, a pseudo random number generation unit 102, a key selection unit 103, a base selection control unit 104, a carrier wave generation unit 105, an M-ary. An intensity modulation unit 106, a data series randomization unit 107, and a transmission data generation unit 108 are configured.

  The pseudo-random number generator 101 sequentially generates random numbers from the first initial key that is a common key. The generated random number becomes the first Running key for encryption. The pseudo-random number generator 102 generates a second Running key from a second initial key that is a common key different from the first initial key. Similar to the first running key, the generated random number becomes the second running key for encryption.

  The key selection unit 103 selects an encryption key used for encryption of the header information management unit or payload portion of the frame according to the timing information received from the plaintext data transmission apparatus. The timing information is information indicating the timing for reading the header information management unit or payload portion stored in the frame, and stores the position and time from the header signal. The first initial key and the second initial key are bit string data of about 100 bits, and are stored in, for example, a memory (not shown).

  The base selection control unit 104 determines which base is used to transmit data from among a plurality of (M) bases stored in advance and a base of binary optical signals carrying transmission data as one set. The selection is made using the first running key or the second running key.

  The carrier wave generation unit 105 is composed of, for example, a semiconductor LD and generates a carrier wave. The M-ary intensity modulation unit 106 performs multi-level intensity modulation on the optical intensity of the carrier wave generated by the carrier wave generation unit 105 using the base selected from the M types by the base selection control unit 104.

  The data series randomizing unit 107 encrypts the transmission data generated by the transmission data generating unit 108 using the first running key or the second running key. Transmission data generation section 108 generates binary transmission data 1 or 0 from a frame to be transmitted, and outputs the transmission data randomized by data sequence randomization section 107 to M-ary intensity modulation section 106. . The generated transmission data is generated as a multilevel optical signal intensity-modulated by the M-ary intensity modulation unit 106 according to the base selected using the first or second running key, and is transmitted to the Y-00 relay apparatus 200. Sent. Next, the Y-00 relay device 200 will be described.

  FIG. 4 is a block diagram illustrating a functional configuration of the Y-00 relay apparatus 200. As shown in FIG. 4, the Y-00 relay apparatus 200 includes a pseudo random number generation unit 201, a base selection control unit 202, an optical switch unit 203, a photodiode 204, an intensity determination unit 205, and a signal determination unit 206. And a data series restructuring unit 207, a frame detection unit 208, and an optical switch control unit 209.

  The pseudo-random number generation unit 201 generates a first Running key from the first initial key, like the pseudo-random number generation unit 101 of the Y-00 transmission apparatus 100. Similar to the base selection control unit 104 of the Y-00 transmission apparatus 100, the base selection control unit 202 selects a base for data transmission from a plurality of bases using the first Running key. Since the regular relay device has the same first running key as the transmission device, the relay side can understand the basis applied to the transmission signal.

  The optical switch unit 203 outputs the multilevel optical signal received from the Y-00 transmitting apparatus 100 and also receives the multilevel optical signal at the destination indicated in the destination information stored in the header management information unit of the decoded frame. A multi-level optical signal is transmitted. The photodiode 204 photoelectrically converts the multilevel optical signal output from the optical switch unit 203.

  The intensity determination unit 205 determines the light intensity of the photoelectrically converted multilevel optical signal. The signal determination unit 206 selects a reception threshold for multilevel signal determination using the first Running key for which the base selection control unit 202 has selected the base, and uses this reception threshold to determine the multilevel light whose light intensity has been determined. The signal is binarized.

  The data series restructuring unit 207 decodes the binarized multilevel optical signal using the first Running key and outputs a frame that is transmission data. The frame detection unit 208 detects the header information management unit or the payload unit from the decoded frame with reference to the timing information. The timing information stores the same contents as the timing information received by the Y-00 transmitting apparatus 100 from the plaintext data transmitting apparatus, and may be stored in advance by the Y-00 relay apparatus 200, or may be transmitted together with the frame with the Y-00 transmission. You may receive from the apparatus 100. FIG.

  The optical switch control unit 209 reads the destination indicated in the destination information included in the detected header management information, and outputs the destination to the optical switch unit 203. In the example illustrated in FIG. 1, one Y-00 relay device 200 is illustrated, but actually one or a plurality of Y-00 relay devices 200 are connected to the optical network, and each relay device is the same. The destination information stored in the header management information part encrypted by the first key is read and the frames are sequentially transmitted to the other Y-00 relay apparatus 200. Next, the Y-00 receiving device 300 will be described.

  FIG. 5 is a block diagram illustrating a functional configuration of the Y-00 receiving device 300. As shown in FIG. 5, the Y-00 receiver 300 includes a pseudo random number generation unit 301, a pseudo random number generation unit 302, a key selection unit 303, a base selection control unit 304, a photodiode 305, and an intensity determination unit. 306, a signal determination unit 307, a data series reconstruction unit 308, and a frame detection unit 309.

  The pseudo-random number generator 301, the pseudo-random number generator 302, the key selection unit 303, and the base selection control unit 304 have the same functions as the Y-00 transmission device 100, and include a photodiode 305, an intensity determination unit 306, and a signal determination unit. 307, the data sequence reconstruction unit 308, and the frame detection unit 309 have the same functions as the Y-00 relay apparatus 200. Since these units have already been described, a detailed description thereof will be omitted. However, the Y-00 receiving device 300 uses the same first and second running keys as those of the Y-00 transmitting device 100 and the Y-00 relay device 200. To select a reception threshold for multi-level signal determination, and using this reception threshold, the multi-level optical signal whose light intensity is determined is binarized, and the binarized multi-level optical signal is converted into a first running key and Decoding is performed using the second Running key, and a frame that is transmission data is output. Similar to the Y-00 relay apparatus 200, the frame detection unit 309 detects the header information management unit or the payload unit from the decoded frame with reference to the timing information.

  As described above, the Y-00 transmitting apparatus 100 and the Y-00 receiving apparatus 300 encrypt and decrypt the frame to be transmitted using the first running key and the second running key, and the Y-00 relay apparatus 200 uses the first running key and the second running key. Since only the header management information storing the destination information included in the frame is decrypted using the first Running key, the data included in the frame remains encrypted at the relay point of the optical network other than the transmission source and the transmission destination. It is possible to determine a destination required for routing in the state and transmit data to the transmission destination. Conventionally, encrypted communication using the Y-00 protocol is performed using a one-to-one dedicated line, but connection to an all-optical network is possible, and physical encrypted transmission within the optical network is possible.

(Example 2)
The first embodiment has been described on the assumption that the header management information part of the frame in which the destination information is stored is encrypted. However, when it is not necessary to encrypt the destination information, only the payload part is encrypted and transmitted. It is also possible. Therefore, in the second embodiment, a case where the header management information part is transmitted in plain text will be described.

  FIG. 6 is a diagram illustrating a configuration example of the optical communication system according to the present embodiment. As shown in FIG. 6, in the optical communication system according to the second embodiment, unlike the first embodiment, the first initial key among the Y-00 transmission apparatus 100, the Y-00 relay apparatus 200, and the Y-00 reception apparatus 300 is used. The Y-00 relay device 200 reads plaintext destination information and transmits the frame to the Y-00 receiving device 300 without encryption using the first Running key using.

  FIG. 7 is a diagram showing a configuration example of a frame transmitted and received in this system. As shown in FIG. 7, in the frame transmitted / received in the optical communication system according to the second embodiment, the header information management unit is plaintext, while the payload unit is encrypted with the second Running key using the second initial key. Yes.

  FIG. 8 is a block diagram showing a functional configuration of the Y-00 transmission apparatus 600 shown in FIG. As shown in FIG. 8, the Y-00 transmission apparatus 600 includes a pseudo random number generation unit 602, a carrier wave generation unit 605, an M-ary intensity modulation unit 606, and a data sequence randomization unit 607 similar to those in the first embodiment. And a transmission data generating unit 608. The key selection unit 603 and the basis selection control unit 604 are different from the first embodiment in that the first running key is not selected (that is, whether the second running key is selected). Since the basic processing is the same as in the first embodiment, description of each unit is omitted here, but the generated transmission data is subjected to M-ary intensity modulation according to the basis selected using the second Running key. It is generated as a multilevel optical signal whose intensity is modulated by the unit 106 and transmitted to the Y-00 relay apparatus 700. Next, the Y-00 relay device 700 will be described.

  FIG. 9 is a block diagram showing a functional configuration of the Y-00 relay apparatus 700. As shown in FIG. As shown in FIG. 9, the Y-00 relay apparatus 700 includes an optical switch unit 703, a photodiode 704, an intensity determination unit 705, a frame detection unit 708, and an optical switch control unit 709 similar to those in the first embodiment. It is comprised. In the second embodiment, since the Y-00 relay apparatus 700 does not need to decrypt the destination information in the header management information section, the pseudo-random number generation section 201 that generates the first Running key, the base selection control section 202, the data sequence re-transmission section, and the like. Each part corresponding to the construction part 207 is not provided. The signal determination unit 706 is different from the first embodiment in that the multilevel optical signal whose light intensity is determined is binarized using a predetermined reception threshold. Since the basic processing is the same as in the first embodiment, description of each unit is omitted here, but the destination information stored in the plaintext header information management unit is read by the Y-00 relay apparatus 700. To other Y-00 relay device 700 or Y-00 receiving device 800. Next, the Y-00 receiving device 800 will be described.

  FIG. 10 is a block diagram showing a functional configuration of the Y-00 receiver 800. As shown in FIG. As shown in FIG. 10, the Y-00 receiver 800 includes a pseudo random number generator 802, a key selector 803, a base selection controller 804, a photodiode 805, a strength determiner 806, and a signal determiner 807. And a data series reconstruction unit 808 and a frame detection unit 809.

  The pseudo random number generation unit 802, the key selection unit 803, and the base selection control unit 804 have the same functions as the Y-00 transmission device 600, and the photodiode 805, the strength determination unit 806, and the frame detection unit 809 have Y functions. -00 has the same function as the relay device 700. The signal determination unit 807 selects a reception threshold for multilevel signal determination using the second Running key for which the base selection control unit 804 has selected the base, and uses this reception threshold to determine the multilevel light whose light intensity has been determined. Unlike the first embodiment, the data sequence restructuring unit 808 decodes the binarized multilevel optical signal using the second Running key and outputs a frame that is transmission data, in that the signal is binarized. This is different from the first embodiment.

  In the Y-00 receiver 800 in the second embodiment, a reception threshold for multilevel signal determination is selected using the same second running key as the Y-00 transmitter 600, and the light intensity is determined using this reception threshold. The binarized multilevel optical signal is binarized, and the binarized multilevel optical signal is decoded using the second running key, and a frame as transmission data is output. The frame detection unit 809 detects the header information management unit or the payload unit from the decoded frame with reference to the timing information, as in the first embodiment.

  As described above, the Y-00 transmission apparatus 600 and the Y-00 reception apparatus 800 in the second embodiment encrypt and decrypt a frame to be transmitted using the second Running key, and the Y-00 relay apparatus 200 uses the second Running key. The destination information stored in plain text is read, the destination necessary for routing is determined in a state where the data included in the frame is encrypted, and the destination information is transmitted to the destination. Therefore, compared with the case of Example 1, the structure of each apparatus and relay apparatus of a transmission side and a reception side can be simplified. Further, since it is not necessary to perform encryption using two types of encryption keys, the processing load can be reduced.

100 Y-00 transmitter 101, 102 Pseudorandom number generator (transmitter)
103 Key selection unit (transmission device)
104 Base selection control unit (transmission device)
105 Carrier wave generator (transmitter)
106 M-ary intensity modulator (transmitter)
107 Data series randomizing unit (transmitting device)
108 Transmission data generator (transmission device)
200 Y-00 relay device 201 pseudo-random number generator (relay device)
202 Base selection control unit (relay device)
203 Optical switch (relay device)
204 Photodiode (relay device)
205 Strength determination unit (relay device)
206 Signal determination unit (relay device)
207 Data sequence reconstruction unit (relay device)
208 Frame detector (relay device)
209 Optical switch controller (relay device)
300 Y-00 receiver 301, 302 Pseudorandom number generator (receiver)
303 Key selection unit (receiving device)
304 Basis selection control unit (receiving device)
305 Photodiode (receiver)
306 Strength determination unit (receiving device)
307 Signal determination unit (receiving device)
308 Data sequence reconstruction unit (receiving device)
309 Frame detector (receiver)
N Optical network.

Claims (8)

An optical transmission device that modulates data into an optical signal and transmits it using optical communication quantum cryptography based on multilevel intensity modulation,
A second pseudo-random number generator for generating a second Running key;
A key selection unit that selects the second Running key based on timing information;
A randomization unit that receives as input binary data having a header information management unit including a destination information generated by a transmission data generation unit and a data unit, and encrypts the data unit based on a second Running key;
Based on the selected second running key, the intensity modulation unit that multi-value modulates the optical intensity of the carrier wave generated by the carrier wave generation unit and transmits the encrypted data;
An optical transmission device comprising: A first pseudo-random number generator for generating a first Running key;
The key selection unit selects the first running key or the second running key based on timing information,
The randomizing unit encrypts a header information management unit including the destination information based on a first Running key,
The intensity modulation unit multi-value modulates the light intensity based on the selected first and second running keys, and transmits the encrypted data.
The optical transmitter according to claim 1. An optical repeater that relays data transmitted by modulating an optical signal from an optical transmitter using optical communication quantum cryptography based on multilevel intensity modulation,
A signal determination unit that binarizes multi-value modulation data, the data portion of which has been encrypted by the second Running key received from the optical transmission device, based on a predetermined threshold;
A detection unit for detecting destination information held in the header information management unit included in the binarized multi-level modulation data;
An optical switch that transmits the data to another optical repeater or an optical receiver according to the detected destination information;
An optical repeater comprising: A first pseudo-random number generator for generating a first Running key;
The signal determination unit receives the multi-value modulation data received from the optical transmission device, the header information management unit including destination information encrypted by the first Running key and the data unit encrypted by the second Running key. As an input, the header information management unit is binarized based on the first Running key,
A reconstructing unit that decrypts the header information management unit including the destination information held in the binarized data based on the first Running key;
A detection unit for detecting destination information held in the decoded header information management unit;
The optical repeater according to claim 3, further comprising: An optical receiver that receives data transmitted by modulating an optical signal from an optical transmitter using optical communication quantum cryptography based on multilevel intensity modulation,
A second pseudo-random number generator for generating a second Running key;
A key selection unit that selects the second Running key based on timing information;
A signal determination unit that binarizes the data part included in the multilevel modulation data received from the optical transmission apparatus or the relay apparatus and having the data part encrypted by the second Running key based on the second Running key; ,
A reconstructing unit for decrypting the data part based on a second Running key;
An optical receiving device comprising: A first pseudo-random number generator for generating a first Running key;
The key selection unit selects the first Running key or the second Running key based on timing information; and
Received from the optical transmission apparatus or the relay apparatus is the header information management unit including the destination information encrypted by the first Running key and the multi-value modulation data in which the data unit is encrypted by the second Running key. A signal determination unit that binarizes the header information management unit based on a first running key and binarizes the data unit based on a first running key;
A reconstructing unit that decrypts the header information management unit based on a first Running key and decrypts the data unit based on a second Running key;
The optical receiver according to claim 5, further comprising: An optical transmission system that uses optical communication quantum cryptography with multi-value intensity modulation to modulate and transmit data to an optical signal,
The optical transmitter
A transmission side first pseudo-random number generator for generating a first Running key;
A second pseudo-random number generator on the transmission side for generating a second Running key;
A transmission side key selection unit that selects the first Running key or the second Running key based on timing information;
The binary data having the header information management unit including the destination information generated by the transmission data generation unit and the data unit is input, and the header information management unit including the destination information is encrypted based on the first Running key. A randomization unit that encrypts the data part based on a second Running key;
An intensity modulation unit that multi-value modulates the optical intensity of the carrier wave generated by the carrier wave generation unit based on the selected first and second running keys, and transmits the encrypted data; With
The optical repeater that relays the optical signal is:
A relay-side first pseudo-random number generator for generating a first Running key;
Received from the optical transmission apparatus is a header information management unit including destination information encrypted by the first Running key, and multi-level modulation data in which the data unit is encrypted by the second Running key. A relay-side signal determination unit that binarizes the management unit based on the first Running key;
A relay side reconstruction unit that decrypts the header information management unit including the destination information held in the binarized data based on the first Running key;
A relay side detection unit for detecting destination information held in the decrypted header information management unit;
A relay-side optical switch that transmits the data to another optical repeater or an optical receiver according to the detected destination information,
The optical receiver
A first pseudo-random number generator on the receiving side for generating a first Running key;
A second pseudorandom number generator on the receiving side for generating a second Running key;
A receiving side key selection unit for selecting the first running key or the second running key based on timing information;
Received from the optical transmission apparatus or the relay apparatus is the header information management unit including the destination information encrypted by the first Running key and the multi-value modulation data in which the data unit is encrypted by the second Running key. A reception-side signal determination unit that binarizes the header information management unit based on a first Running key, and binarizes the data unit based on a first Running key;
A receiving side reconstruction unit that decrypts the header information management unit based on a first Running key and decrypts the data unit based on a second Running key;
An optical communication system comprising: An optical transmission method for modulating and transmitting data to an optical signal using optical communication quantum cryptography by multi-value intensity modulation,
Transmission-side key selection for selecting the first Running key generated by the transmission-side first pseudo-random number generation unit or the second Running key generated by the transmission-side second pseudo-random number generation unit based on the timing information Steps,
The binary data having the header information management unit including the destination information generated by the transmission data generation unit and the data unit is input, and the header information management unit including the destination information is encrypted based on the first Running key. A randomizing step of encrypting the data portion based on a second Running key;
An intensity modulation step of multi-level modulating the optical intensity of the carrier wave generated by the carrier wave generator based on the selected first and second running keys, and transmitting the encrypted data; ,
Received from the optical transmission apparatus is a header information management unit including destination information encrypted by the first Running key, and multi-level modulation data in which the data unit is encrypted by the second Running key. A relay side signal determination step of binarizing the management unit based on the first Running key;
A relay side reconstruction step of decrypting the header information management unit including the destination information held in the binarized data based on the first Running key;
A relay side detection step of detecting destination information held in the decrypted header information management unit;
A relay-side optical switch step for transmitting the data to another optical repeater or an optical receiver in accordance with the detected destination information;
Receiving-side key selection for selecting the first Running key generated by the receiving-side first pseudo-random number generator or the second Running key generated by the receiving-side second pseudo-random number generator based on the timing information Steps,
Received from the optical transmission apparatus or the relay apparatus is the header information management unit including the destination information encrypted by the first Running key and the multi-value modulation data in which the data unit is encrypted by the second Running key. A reception-side signal determination step of binarizing the header information management unit based on a first Running key and binarizing the data unit based on a first Running key;
A receiving side reconstruction step of decrypting the header information management unit based on a first Running key and decrypting the data unit based on a second Running key;
An optical communication method comprising:

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