JP7823446B2 - Communication system, transmitting device, receiving device, processing method, and program - Google Patents

Description

This disclosure relates to a communication system, a transmitting device, a receiving device, a processing method, and a program.

With the spread of computers and networks, communications are becoming more common in a variety of fields. The data handled in these communications is often large, creating a demand for high-speed communications. For this reason, optical communications are increasingly being used in applications such as submarine cables and inter-satellite communications. Patent Document 1 discloses related technology, including technology related to optical communications systems.

Japanese Patent Application Laid-Open No. 2021-136489

Recently, cyber attacks have been increasing, and there is a demand for secure communications. This is also true for optical communications, which enable high-speed communications.
Therefore, there is a demand for technology that enables secure communication in optical communications.

Each aspect of the present disclosure aims to provide a communication system, transmitting device, receiving device, processing method, and program that can solve the above problems.

To achieve the above object, according to one aspect of the present disclosure, a communication system includes a transmitting device and a receiving device, wherein the transmitting device includes a synchronization means for synchronizing time with the receiving device, a control means for controlling encryption of an optical signal based on a rule set for each of a plurality of periods indicated by the time, a generation means for generating an encrypted optical signal for each of the plurality of periods based on control by the control means, and a transmitting means for transmitting the encrypted optical signal to the receiving device during one of the plurality of periods, and the receiving device includes a synchronization means for synchronizing time with the transmitting device, a receiving means for receiving the encrypted optical signal during the one period, a conversion means for converting the encrypted optical signal received by the receiving means into an electrical signal, and a decryption means for decrypting the electrical signal based on a rule set for each of the plurality of periods.

To achieve the above object, according to another aspect of the present disclosure, a processing method is executed by a communication system including a transmitting device and a receiving device, in which the transmitting device synchronizes time with the receiving device, controls encryption of an optical signal based on rules set for each of a plurality of periods indicated by the time, generates an encrypted optical signal for each of the plurality of periods based on the control, and transmits the encrypted optical signal to the receiving device during one of the plurality of periods, and the receiving device synchronizes time with the transmitting device, receives the encrypted optical signal during the one period, converts the received encrypted optical signal into an electrical signal, and decrypts the electrical signal based on rules set for each of the plurality of periods.

To achieve the above object, according to another aspect of the present disclosure, a transmitting device includes a synchronization means for synchronizing time with a receiving device with which the transmitting device communicates, a control means for controlling the encryption of an optical signal based on a rule set for each of a plurality of periods indicated by the time, a generation means for generating an encrypted optical signal for each of the plurality of periods based on control by the control means, and a transmission means for transmitting the encrypted optical signal to the receiving device during one of the plurality of periods.

To achieve the above object, according to another aspect of the present disclosure, a processing method includes: synchronizing time with a receiving device that is a communication target; controlling encryption of an optical signal based on rules set for each of a plurality of time periods indicated by the time; generating an encrypted optical signal for each of the plurality of time periods based on the control; and transmitting the encrypted optical signal to the receiving device during one of the plurality of time periods.

To achieve the above object, according to another aspect of the present disclosure, a program causes a computer to synchronize time with a receiving device with which communication is to be performed, control the encryption of an optical signal based on rules set for each of multiple periods indicated by the time, generate an encrypted optical signal for each of the multiple periods based on the control, and transmit the encrypted optical signal to the receiving device during one of the multiple periods.

To achieve the above object, according to another aspect of the present disclosure, a receiving device includes a synchronization means for synchronizing time with a transmitting device with which the receiving device is communicating, a receiving means for receiving an optical signal encrypted by the transmitting device during one of a plurality of periods indicated by the time, a conversion means for converting the encrypted optical signal received by the receiving means into an electrical signal, and a decoding means for decrypting the electrical signal based on a protocol set for each of the plurality of periods.

To achieve the above object, according to another aspect of the present disclosure, a processing method includes: synchronizing time with a transmitting device with which communication is to be performed; receiving, during one of a plurality of periods indicated by the time, an optical signal encrypted by the transmitting device during the one period; converting the received encrypted optical signal into an electrical signal; and decrypting the electrical signal based on a protocol established for each of the plurality of periods.

To achieve the above object, according to another aspect of the present disclosure, a program causes a computer to synchronize time with a transmitting device with which communication is to be performed, receive an optical signal encrypted by the transmitting device during one of multiple periods indicated by the time, convert the received encrypted optical signal into an electrical signal, and decrypt the electrical signal based on rules set for each of the multiple periods.

Each aspect of the present disclosure makes it possible to enable secure optical communications.

FIG. 1 is a diagram illustrating an example of a configuration of a communication system according to an embodiment of the present disclosure. FIG. 10 is a diagram illustrating an example of a rule according to an embodiment of the present disclosure. 10A and 10B are diagrams illustrating an example of a multi-bit signal for each unit time output by a light source device according to another embodiment of the present disclosure. FIG. 10 is a diagram illustrating an example of a communication processing flow according to an embodiment of the present disclosure. FIG. 1 is a diagram illustrating an example of a minimum configuration of a communication system according to an embodiment of the present disclosure. FIG. 10 is a diagram illustrating an example of a processing flow of a communication system with a minimum configuration according to an embodiment of the present disclosure. FIG. 1 is a schematic block diagram illustrating the configuration of a computer according to at least one embodiment.

Hereinafter, the embodiments will be described in detail with reference to the drawings.
<Embodiment>
(Configuration of communication system)
A communication system 1 according to an embodiment of the present disclosure will be described with reference to the drawings. The communication system 1 is a system that encrypts an optical signal of plaintext (original data) to be transmitted and decrypts an optical signal of received data into plaintext based on a predetermined protocol. An example of communication modulation in the communication system 1 is binary intensity modulation.

Figure 1 is a diagram illustrating an example of the configuration of a communication system 1 according to an embodiment of the present disclosure. As shown in Figure 1, the communication system 1 includes a transmitting device 10, a receiving device 20, and a transmission path 30. The transmitting device 10 and the receiving device 20 are connected to each other via the transmission path 30 so that they can communicate with each other. An example of the transmission path 30 is optical fiber.

Transmitting device 10 is a device that generates an optical signal in which plaintext is encrypted and transmits the generated optical signal to receiving device 20 via transmission path 30. As shown in FIG. 1, transmitting device 10 includes a synchronization device 101 (an example of synchronization means), a storage device 102, an input device 103, a processing device 104 (an example of control means), a light source device 105 (an example of generation means), and a multiplexer 106 (an example of transmission means).

The synchronization device 101 synchronizes the time on the transmitting device 10 with the time on the receiving device 20. For example, the synchronization device 101 receives radio waves indicating a time generated based on the time of an atomic clock, and synchronizes its own time to the time indicated by the received radio waves. Furthermore, the synchronization device 201 (described below) provided in the receiving device 20 receives radio waves indicating a time generated based on the time of an atomic clock, and synchronizes its own time to the time indicated by the received radio waves. In this way, the time on the transmitting device 10 and the time on the receiving device 20 can be synchronized.

The storage device 102 stores various information necessary for the processing performed by the transmitting device 10. Figure 2 is a diagram showing an example of a convention TBL1 in one embodiment of the present disclosure. For example, the storage device 102 stores a convention TBL1 that indicates the relationship between each unit time, which is indicated as the time from one time to another, and the frequency of the optical signal used in each unit time. In the example of the convention TBL1 shown in Figure 2, the storage device 102 stores a convention TBL1 that includes the relationship between each unit time and the frequency of the optical signal used in each unit time, as well as the light source and light receiving element corresponding to that frequency. In the convention TBL1 shown in Figure 2, each unit time is associated with the frequency of the optical signal, the light source, and the light receiving element.

The input device 103 accepts information to be transmitted from the transmitting device 10 to the receiving device 20. Examples of the input device 103 include a keyboard, a mouse, a touch panel, etc.

The processing device 104 controls the light emission of the light source device 105 based on the protocol table 11, thereby generating an encrypted optical signal corresponding to the information received by the input device 103. For example, the processing device 104 acquires information indicating the protocol table 11 from the storage device 102. The processing device 104 also acquires information indicating the time from the synchronization device 101. The processing device 104 identifies the time in the information acquired from the synchronization device 101. The processing device 104 identifies which unit of time the identified time is included in the acquired protocol table 11, and identifies the frequency of the optical signal to be used in that unit of time. The processing device 104 then controls the light emission of the light sources 105a1, 105a2, 105a3, ..., 105an in the light source device 105, as described below, so that the information received by the input device 103 is output as an optical signal of the identified frequency. Hereinafter, the light sources 105a1, 105a2, 105a3, ..., 105an will be collectively referred to as light source 105a.

For example, if the rule TBL1 is the rule shown in FIG. 2 and the time indicated by the information acquired by the processing device 104 from the synchronization device 101 is greater than or equal to time t1 and less than t2, the processing device 104 specifies the unit time T1 in the rule TBL1 shown in FIG. 2 and specifies the frequency 1 of the optical signal associated with the specified unit time T1. The processing device 104 then controls the light emission of the light source 105a1 capable of outputting light of that frequency so that an optical signal of the specified frequency 1 is output. Furthermore, if the time indicated by the information acquired by the processing device 104 from the synchronization device 101 is greater than or equal to time t2 and less than t3, the processing device 104 specifies the unit time T2 in the rule TBL1 shown in FIG. 2 and specifies the frequencies 2 and n of the optical signal associated with the specified unit time T2. The processing device 104 then controls the light emission of the light sources 105a2 and 105an capable of outputting light of that frequency so that an optical signal of the specified frequency 2 and n is output. Furthermore, if the time indicated by the information acquired by the processing device 104 from the synchronization device 101 is equal to or greater than time t3 and less than time t4, the processing device 104 specifies unit time T3 in the rule TBL1 shown in FIG. 2 and specifies frequencies 2 and 3 of the optical signal associated with the specified unit time T3. The processing device 104 then controls the light emission of the light sources 105a2 and 105a3 capable of outputting light of the specified frequencies 2 and 3 so that optical signals of those frequencies are output. Furthermore, if the time indicated by the information acquired by the processing device 104 from the synchronization device 101 is equal to or greater than time t4 and less than time t5, the processing device 104 specifies unit time T4 in the rule TBL1 shown in FIG. 2 and specifies frequency n of the optical signal associated with the specified unit time T4. The processing device 104 then controls the light emission of the light source 105an capable of outputting light of that frequency so that an optical signal of the specified frequency n is output. Furthermore, if the time indicated by the information acquired by the processing device 104 from the synchronization device 101 is equal to or greater than time t5 and less than time t6, the processing device 104 identifies the unit time T5 in the rules TBL1 shown in FIG. 2 and identifies the frequencies 1, 2, and n of the optical signal associated with the identified unit time T5. The processing device 104 then controls the light emission of the light sources 105a1, 105a2, and 105an capable of outputting light of the identified frequencies 1, 2, and n so that optical signals of those frequencies are output.

The processing device 104 may also control the light sources 105a corresponding to the frequencies of the optical signals not used in that unit time to emit light randomly (i.e., emit light as dummy signals). For example, in the example shown here, the processing device 104 may randomly emit light from light sources other than light source 105a1 during unit time T1, randomly emit light from light sources other than light sources 105a2 and 105an during unit time T2, randomly emit light from light sources other than light sources 105a2 and 105a3 during unit time T3, randomly emit light from light sources other than light source 105an during unit time T4, and randomly emit light from light sources other than light source 105a1, 105a2, and 105an during unit time T5. In the example shown in FIG. 1, the dashed line portion of the signal output by the light source device 105 is an encrypted signal, and the solid line portion is a dummy signal. The output signal from the light source device 105 shown in FIG. 1 is an example in which the light source device 105 outputs a 1-bit signal per unit time. In other embodiments, the light source device 105 may output a multi-bit signal per unit time. FIG. 3 is a diagram showing an example of a multi-bit signal per unit time output by a light source device 105 according to another embodiment of the present disclosure. For example, as shown in FIG. 3, the light source device 105 according to another embodiment of the present disclosure may transmit three bits of data per unit time. In this case, encrypted signals and dummy signals can be arbitrarily combined per unit time. This enables more secure communication than when either a one-bit encrypted signal or a one-bit dummy signal is transmitted per unit time. Furthermore, increasing the proportion of encrypted signals makes it possible to increase communication capacity.

Under the control of the processing device 104, the light source device 105 generates an optical signal generated (i.e., encrypted) based on the protocol TBL1. As shown in FIG. 1, the light source device 105 includes light sources 105a1, 105a2, 105a3, ..., 105an. Each light source 105a emits light at one of the multiple frequencies indicated in the protocol TBL1. Before initiating communication between the transmitting device 10 and the receiving device 20, the transmitting device 10 and the receiving device 20 share common information, including the protocol TBL1 that enables the decryption of encrypted signals, such as whether to output a single-bit signal or a multi-bit signal for each unit of time in communication at each time point (e.g., by using a separate, highly confidential communication device or exchanging information via mail, such as paper). This information includes the protocol TBL1, which determines whether to output a single-bit signal or a multi-bit signal for each unit of time in communication, and, if a single-bit signal is output, what logic, such as logical OR, exclusive OR, or logical AND, should be used to represent the signal. The timing at which each light source 105a emits light is controlled by the processing device 104 in accordance with this common information.

In addition, when transmitting a multi-bit signal within each unit time, the rules table 1 may include information indicating which of the multi-bit signals within each unit time should be encrypted signals and which should be dummy signals.

The multiplexer 106 multiplexes multiple optical signals with different wavelengths output by the light source device 105. The multiplexer 106 transmits the multiplexed optical signal to the receiving device 20 via the transmission path 30.

The receiving device 20 generates plaintext by decrypting an encrypted optical signal based on the protocol TBL1. As shown in FIG. 1, the receiving device 20 includes a synchronization device 201 (an example of a synchronization means), a storage device 202, an output device 203, a processing device 204 (an example of a decryption means), a light receiving device 205 (an example of a conversion means), and a splitter 206 (an example of a receiving means).

The synchronization device 201 synchronizes the time on the receiving device 20 with the time on the transmitting device 10. For example, the synchronization device 201 receives radio waves indicating the time generated based on the time of an atomic clock, and synchronizes its own time to the time indicated by the received radio waves. As described above, the synchronization device 101 provided in the transmitting device 10 receives radio waves indicating the time generated based on the time of an atomic clock, and synchronizes its own time to the time indicated by the received radio waves, thereby synchronizing the time on the receiving device 20 with the time on the transmitting device 10.

The storage device 202 stores various information necessary for the processing performed by the receiving device 20. For example, the storage device 202 stores a rule TBL1 that indicates the relationship between each unit time, which is indicated as the time from one time to another, and the frequency of the optical signal used in each unit time.

The demultiplexer 206 demultiplexes multiple optical signals with different wavelengths that have propagated through the transmission path 30 into optical signals with multiple wavelengths. The demultiplexer 206 outputs the demultiplexed optical signals to the optical receiving device 205.

The light receiving device 205 is a device that converts optical signals into electrical signals. As shown in FIG. 1, the light receiving device 205 includes light receiving elements 205a1, 205a2, 205a3, ..., 205an. Hereinafter, the light receiving elements 205a1, 205a2, 205a3, ..., 205an will be collectively referred to as light receiving elements 205a. An example of the light receiving elements 205a is a PIN photodiode. Each light receiving element 205a is provided for each dispersed optical signal. When each light receiving element 205a receives an optical signal, it converts the received optical signal into an electrical signal corresponding to that optical signal (i.e., an electrical signal that differs depending on the frequency of the optical signal), and outputs the converted electrical signal to the processing device 204.

The processing device 204 generates a decrypted electrical signal by extracting an electrical signal identified based on the protocol TBL1 from the electrical signals output by the light receiving device 205. For example, the processing device 204 identifies the time at which the electrical signal was received from the light receiving device 205 based on the time in the synchronization device 201. The processing device 204 identifies a unit time including the time at which the electrical signal was received in the protocol TBL1 stored in the memory device 202, and identifies the frequency of the optical signal to be used in that unit time. Identifying the frequency of this optical signal corresponds to identifying which of the light receiving elements 205a will receive the encrypted optical signal. The processing device 204 then decrypts the electrical signal output by the light receiving element that received the optical signal of the identified frequency based on the protocol TBL1.

Here, we will explain the processing of the transmitting device 10, which transmits data 0, 1, 0, 0, 1 to the receiving device 20 using the signals shown in Figure 1. In this case, protocol TBL1 allows the transmitting device 10 and the receiving device 20 to share information that the dashed line portions of the signal output by the light source device 105 shown in Figure 1 are encrypted signals, and the solid line portions are dummy signals. Protocol TBL1 also allows the transmitting device 10 and the receiving device 20 to share information that the logical sum (OR) of the encrypted signals is calculated at each unit of time (i.e., in the example shown in Figure 1, at each of unit times T1, T2, T3, T4, and T5). This allows the transmitting device 10 to transmit data to the receiving device 20 that is 0 at unit time T1, 1 at unit time T2, 0 at unit time T3, 0 at unit time T4, and 1 at unit time T5. In this case, the receiving device 20 also includes a logic circuit that implements the logical sum (OR). Then, for each of the unit times T1, T2, T3, T4, and T5, the logic circuit calculates a logical sum (OR) for the encrypted signal received by the receiving device 20, allowing the receiving device 20 to decrypt the encrypted signal. As a result, the receiving device 20 can obtain the data 0, 1, 0, 0, 1 transmitted by the transmitting device 10.

Specifically, for example, rule TBL1 is a rule that includes the information shown in FIG. 2 and information that specifies that the logical sum (OR) of encrypted signals is taken for each unit of time to generate data. If the time indicated by the information acquired by processing device 204 from synchronization device 201 is equal to or greater than time t1 and less than time t2, processing device 204 identifies unit of time T1 in rule TBL1 shown in FIG. 2 and identifies frequency 1 of the optical signal associated with the identified unit of time T1. Processing device 204 then identifies light-receiving element 205a1 that received the optical signal with the identified frequency 1. Processing device 204 then calculates the logical sum (OR) of the electrical signals output by the identified light-receiving element 205a1 (in this case, since there is only one input, the result is actually the logic indicated by that electrical signal). The result of this calculation is the decoded signal for unit of time T1. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronization device 201 is equal to or greater than time t2 and less than time t3, the processing device 204 identifies the unit time T2 in the rule table 1 shown in FIG. 2 and identifies the frequencies 2 and n of the optical signal associated with the identified unit time T2. The processing device 204 identifies the light-receiving elements 205a2 and 205an that received the identified optical signals of frequencies 2 and n. The processing device 204 then calculates the logical sum (OR) of the electrical signals output by the identified light-receiving elements 205a2 and 205an. The result of this calculation is the decoded signal for unit time T2. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronization device 201 is equal to or greater than time t3 and less than time t4, the processing device 204 identifies the unit time T3 in the rule table 1 shown in FIG. 2 and identifies the frequencies 2 and 3 of the optical signal associated with the identified unit time T3. The processing device 204 identifies the light-receiving elements 205a2 and 205a3 that received the identified optical signals of frequencies 2 and 3. The processing device 204 then calculates the logical sum (OR) of the electrical signals output by the identified light-receiving elements 205a2 and 205a3. The result of this calculation becomes the decoded signal for unit time T3. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronizer 201 is equal to or greater than time t4 and less than time t5, the processing device 204 identifies unit time T4 in the rule TBL1 shown in FIG. 2 and identifies the frequency n of the optical signal associated with the identified unit time T4. The processing device 204 then identifies the light-receiving element 205an that received the optical signal with the identified frequency n. The processing device 204 then calculates the logical sum (OR) of the electrical signals output by the identified light-receiving element 205an (in this case, since there is only one input, the result is actually the logic indicated by that electrical signal). The result of this calculation becomes the decoded signal for unit time T4. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronizer 201 is equal to or greater than time t5 and less than time t6, the processing device 204 identifies unit time T5 in the rule TBL1 shown in FIG. 2 and identifies the optical signal frequencies 1, 2, and n associated with the identified unit time T5. The processing device 204 identifies the photodetectors 205a1, 205a2, and 205an that received the optical signals with the identified frequencies 1, 2, and n. The processing device 204 then calculates the logical sum (OR) of the electrical signals output by the identified photodetectors 205a1, 205a2, and 205an. The result of this calculation is the decoded signal for unit time T5. The processing device 204 then outputs the results of the calculations performed for each of unit times T1, T2, T3, T4, and T5, i.e., the decoded signals, to the output device 203.

The transmitting device 10 can also transmit data such as 0, 1, 1, 0, 0, 0, 1, 0, 1 to the receiving device 20 using the signals shown in FIG. 1. In this case, protocol TBL1 allows the transmitting device 10 and the receiving device 20 to share information that the dashed line portions of the signals output by the light source device 105 shown in FIG. 1 are encrypted signals, and the solid line portions are dummy signals. Protocol TBL1 also allows the transmitting device 10 and the receiving device 20 to share information that encrypted signals are transmitted in sequence as data at each unit of time (i.e., in the example shown in FIG. 1, at each of unit times T1, T2, T3, T4, and T5). This allows the transmitting device 10 to transmit data to the receiving device 20 as follows: 0 at unit time T1, 1, 1 at unit time T2, 0, 0 at unit time T3, 0 at unit time T4, and 1, 0, 1 at unit time T5. In this case, the receiving device 20 can decrypt the encrypted signal by assembling the encrypted signal received by the receiving device 20 into data in the order given in each of the unit times T1, T2, T3, T4, and T5. As a result, the receiving device 20 can obtain the data 0, 1, 1, 0, 0, 0, 1, 0, 1 transmitted by the transmitting device 10.

Specifically, for example, rule TBL1 is a rule that includes the information shown in FIG. 2 and information that the encrypted signal for each unit time is treated as data as is. If the time indicated by the information acquired by the processing device 204 from the synchronization device 201 is greater than or equal to time t1 and less than time t2, the processing device 204 identifies the unit time T1 in rule TBL1 shown in FIG. 2 and identifies frequency 1 of the optical signal associated with the identified unit time T1. The processing device 204 identifies the light-receiving element 205a1 that received the optical signal with the identified frequency 1. The processing device 204 then regards the electrical signal output by the identified light-receiving element 205a1 as the decoded signal for unit time T1. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronization device 201 is greater than or equal to time t2 and less than time t3, the processing device 204 identifies the unit time T2 in rule TBL1 shown in FIG. 2 and identifies frequencies 2 and n of the optical signal associated with the identified unit time T2. The processing device 204 identifies the photodetectors 205a2 and 205an that received the identified optical signals of frequencies 2 and n. The processing device 204 then determines the electrical signals output by the identified photodetectors 205a2 and 205an as the decoded signals for unit time T2. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronizer 201 is equal to or greater than time t3 and less than time t4, the processing device 204 identifies the unit time T3 in the rules TBL1 shown in FIG. 2 and identifies the frequencies 2 and 3 of the optical signal associated with the identified unit time T3. The processing device 204 then identifies the photodetectors 205a2 and 205a3 that received the identified optical signals of frequencies 2 and 3. The processing device 204 then determines the electrical signals output by the identified photodetectors 205a2 and 205a3 as the decoded signals for unit time T3. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronization device 201 is equal to or greater than time t4 and less than time t5, the processing device 204 identifies the unit time T4 in the rule table 1 shown in FIG. 2 and identifies the frequency n of the optical signal associated with the identified unit time T4. The processing device 204 identifies the light-receiving element 205an that received the optical signal of the identified frequency n. The processing device 204 then regards the electrical signal output by the identified light-receiving element 205an as the decoded signal for the unit time T4. Furthermore, if the time indicated by the information acquired by the processing device 204 from the synchronization device 201 is equal to or greater than time t5 and less than time t6, the processing device 204 identifies the unit time T5 in the rule table 1 shown in FIG. 2 and identifies the frequencies 1, 2, and n of the optical signal associated with the identified unit time T5. The processing device 204 identifies the light-receiving elements 205a1, 205a2, and 205an that received the optical signals of the identified frequencies 1, 2, and n. The processing device 204 then regards the electrical signals output by the identified light receiving elements 205a1, 205a2, and 205an as the decoded signals for unit time T5. The processing device 204 then outputs the decoded signals for unit times T1, T2, T3, T4, and T5 to the output device 203.

The output device 203 notifies the user of the decoded signal. Examples of the output device 203 include a device such as a display that displays the decoded signal, a printing device that prints the decoded signal, and a communication device that transmits the decoded signal outside the receiving device 20.

Next, the processing performed by the communication system 1 according to an embodiment of the present disclosure will be described. Figure 4 is a diagram showing an example of the processing flow of the communication system 1 according to an embodiment of the present disclosure. Here, the encryption and decryption processing performed by the communication system 1 will be described assuming that the convention TBL1 is the convention shown in Figure 2. Note that it is assumed that the time indicated by the synchronization device 101 provided in the transmitting device 10 and the time indicated by the synchronization device 201 provided in the receiving device 20 are the same.

The input device 103 accepts information to be transmitted from the transmitting device 10 to the receiving device 20 (step S1).

The processing device 104 generates an encrypted optical signal that corresponds to the information received by the input device 103 by controlling the light emission of the light source device 105 based on the rules TBL1 (step S2). For example, the processing device 104 acquires information indicating the rules TBL1 from the storage device 102. The processing device 104 also acquires information indicating the time from the synchronization device 101. The processing device 104 identifies the time in the information acquired from the synchronization device 101. The processing device 104 identifies which unit of time the identified time is included in the acquired rules TBL1, and identifies the frequency of the optical signal to be used in that unit of time. The processing device 104 then controls the light emission of the light sources 105a1, 105a2, 105a3, ..., 105an in the light source device 105 so that the information received by the input device 103 is output as an optical signal of the identified frequency.

For example, if the convention TBL1 is the convention shown in FIG. 2 and the time indicated by the information acquired by the processing device 104 from the synchronization device 101 is greater than or equal to time t1 and less than time t2, the processing device 104 identifies the unit time T1 in the convention TBL1 shown in FIG. 2 and identifies the frequency 1 of the optical signal associated with the identified unit time T1. The processing device 104 then controls the light emission of the light source 105a1 capable of outputting light of the identified frequency 1 so that an optical signal of that frequency is output. The processing device 104 also controls light sources other than the light source 105a1 during the unit time T1 to output a dummy signal. The processing device 104 also controls the light emission of the light source 105a in a similar manner during each of the unit times T2, T3, T4, and T5.

The light source device 105 generates an optical signal generated (i.e., encrypted) based on the protocol TBL1 under the control of the processing device 104.

The multiplexer 106 multiplexes the multiple optical signals with different wavelengths output by the light source device 105 (step S3). The multiplexer 106 transmits the multiplexed optical signal to the receiving device 20 via the transmission path 30.

The demultiplexer 206 demultiplexes (disperses) the multiple optical signals with different wavelengths that have propagated through the transmission path 30 into optical signals with multiple wavelengths (step S4). The demultiplexer 206 outputs the demultiplexed optical signals to the optical receiving device 205.

When each of the light receiving elements 205a included in the light receiving device 205 receives an optical signal, it converts the received optical signal into an electrical signal corresponding to the optical signal (i.e., an electrical signal that differs depending on the frequency of the optical signal), and outputs the converted electrical signal to the processing device 204 (step S5).

The processing device 204 generates a decoded electrical signal by extracting the electrical signal identified based on the rule TBL1 from the electrical signals output by the light receiving device 205 (step S6). For example, the processing device 204 identifies the time at which the electrical signal was received from the light receiving device 205 based on the time in the synchronization device 201. The processing device 204 identifies a unit time including the time at which the electrical signal was received in the rule TBL1 stored in the memory device 202, and identifies the frequency of the optical signal to be used in that unit time. The processing device 204 then decodes the electrical signal output by the light receiving element that received the optical signal of the identified frequency based on the rule TBL1.

Then, the processing device 204 outputs the decoded signals for each unit time T1, T2, T3, T4, and T5 to the output device 203. The output device 203 notifies the decoded signals (step S7).

The foregoing describes a communication system 1 according to one embodiment of the present disclosure. The communication system 1 includes a transmitting device 10 and a receiving device 20. The transmitting device 10 includes a synchronizing device 101 (an example of a synchronizing means) that synchronizes time with the receiving device 20, a processing device 104 (an example of a control means) that controls encryption of an optical signal based on a rule set for each of a plurality of periods indicated by the time, a light source device 105 (an example of a generating means) that generates an encrypted optical signal for each of the plurality of periods based on control by the processing device 104, and a multiplexer 106 (an example of a transmitting means) that transmits the encrypted optical signal during one of the plurality of periods to the receiving device 20 during that one period. The receiving device 20 includes a synchronizing device 201 (an example of a synchronizing means) that synchronizes time with the transmitting device 10, a demultiplexer 206 (an example of a receiving means) that receives the encrypted optical signal during the one period, an optical receiving device 205 (an example of a converting means) that converts the encrypted optical signal received by the demultiplexer 206 into an electrical signal, and a processing device 204 (an example of a decrypting means) that decrypts the electrical signal based on a protocol set for each of the multiple periods. This enables secure communication in optical communications.

Figure 5 is a diagram showing the minimum configuration of a communication system 1 according to an embodiment of the present disclosure. The communication system 1 is a communication system including a transmitting device 10 and a receiving device 20.

The transmitting device 10 includes a synchronization unit 1001 (an example of a synchronization means), a control unit 1002 (an example of a control means), a generation unit 1003 (an example of a generation means), and a transmission unit 1004 (an example of a transmission means).

The synchronization unit 1001 synchronizes time with the receiving device 20. The control unit 1002 controls the encryption of the optical signal based on rules set for each of the multiple periods indicated by the time. The generation unit 1003 generates an encrypted optical signal for each of the multiple periods based on control by the control unit 1002. The transmission unit 1004 transmits the encrypted optical signal to the receiving device 20 during one of the multiple periods.

The receiving device 20 includes a synchronization unit 2001 (an example of a synchronization means), a receiving unit 2002 (an example of a receiving means), a conversion unit 2003 (an example of a conversion means), and a decoding unit 2004 (an example of a decoding means).

The synchronization unit 2001 synchronizes time with the transmitting device 10. The receiving unit 2002 receives the encrypted optical signal during the one period. The conversion unit 2003 converts the encrypted optical signal received by the receiving unit 2002 into an electrical signal. The decryption unit 2004 decrypts the electrical signal based on rules set for each of the multiple periods.

Figure 6 is a diagram showing an example of the processing flow of a communication system 1 with a minimum configuration according to an embodiment of the present disclosure. Next, the processing of a communication system 1 with a minimum configuration according to an embodiment of the present disclosure will be described with reference to Figure 6.

The synchronization unit 1001 synchronizes time with the receiving device 20 (step S101). The control unit 1002 controls the encryption of the optical signal based on rules set for each of the multiple periods indicated by the time (step S102). The generation unit 1003 generates an encrypted optical signal for each of the multiple periods based on control by the control unit 1002 (step S103). The transmission unit 1004 transmits the encrypted optical signal for one of the multiple periods to the receiving device 20 during that one period (step S104).

The synchronization unit 2001 synchronizes time with the transmitting device 10 (step S105). The receiving unit 2002 receives the encrypted optical signal during the one period (step S106). The conversion unit 2003 converts the encrypted optical signal received by the receiving unit 2002 into an electrical signal (step S107). The decryption unit 2004 decrypts the electrical signal based on rules set for each of the multiple periods (step S108).

The above describes a communication system 1 with a minimum configuration according to an embodiment of the present disclosure. This communication system 1 enables secure communication in optical communications.

Note that the order of the processes in the embodiments of the present disclosure may be changed as long as appropriate processing is performed.

Although the embodiments of the present disclosure have been described, the above-mentioned communication system 1, transmitting device 10, receiving device 20, synchronization devices 101, 201, input device 103, processing devices 104, 204, output device 203, and other control devices may have internal computer systems. The above-mentioned processing steps are stored in the form of a program on a computer-readable recording medium, and the above processing is performed by reading and executing this program by a computer. Specific examples of computers are shown below.

Figure 7 is a schematic block diagram showing the configuration of a computer according to at least one embodiment. As shown in Figure 7, the computer 5 includes a CPU 6, main memory 7, storage 8, and interface 9.

For example, the above-mentioned communication system 1, transmitting device 10, receiving device 20, synchronizing devices 101, 201, input device 103, processing devices 104, 204, output device 203, and other control devices are each implemented in a computer 5. The operation of each of the above-mentioned processing units is stored in the form of a program in storage 8. CPU 6 reads the program from storage 8, expands it in main memory 7, and executes the above-mentioned processing in accordance with the program. CPU 6 also allocates storage areas in main memory 7 corresponding to each of the above-mentioned storage units in accordance with the program.

Examples of storage 8 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, magneto-optical disk, CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), semiconductor memory, etc. Storage 8 may be internal media directly connected to the bus of computer 5, or external media connected to computer 5 via interface 9 or a communication line. Furthermore, if this program is distributed to computer 5 via a communication line, the computer 5 that receives the program may expand the program into main memory 7 and execute the above-mentioned processing. In at least one embodiment, storage 8 is a non-transitory, tangible storage medium.

The program may also implement some of the functions described above. Furthermore, the program may be a file that can implement the functions described above in combination with a program already recorded on the computer system, a so-called differential file (differential program).

Several embodiments of the present disclosure have been described, but these embodiments are merely examples and do not limit the scope of the disclosure. Various additions, omissions, substitutions, and modifications may be made to these embodiments without departing from the spirit of the disclosure.

1...Communication system 5...Computer 6...CPU
7...Main memory 8...Storage 9...Interface 10...Transmitting device 20...Receiving device 101, 201...Synchronizing device 102, 202...Storage device 103...Input device 104, 204...Processing device 105...Light source device 105a...Light source 106...Multiplexer 203...Output device 205...Light receiving device 205a...Light receiving element 206...Demultiplexer TBL1...Convention

Claims (11)

A communication system including a transmitting device and a receiving device,
The transmitting device
a synchronization means for synchronizing the time with the receiving device;
a control means for controlling encryption of an optical signal based on a rule set for each of a plurality of periods indicated by the time;
a generating means for generating an encrypted optical signal for each of the plurality of periods under control of the control means;
a transmitting means for transmitting the encrypted optical signal to the receiving device during one of the plurality of periods;
Equipped with
The receiving device
a synchronization means for synchronizing the time with the transmitting device;
a receiving means for receiving the encrypted optical signal during the one period;
a conversion means for converting the encrypted optical signal received by the receiving means into an electrical signal;
a decoding means for decoding the electrical signal based on a rule set for each of the plurality of periods;
A communication system comprising: the rules define a combination of optical signal frequencies to be used for encryption for each of the plurality of time periods,
The control means
controlling encryption of the optical signal based on a combination of frequencies of the optical signal used for encryption for each of the plurality of periods;
The decoding means
decrypting the electrical signal based on a combination of frequencies of optical signals used for encryption for each of the plurality of periods;
The communication system of claim 1 . the optical signal includes a dummy signal having a random light emission timing;
3. The communication system according to claim 1 or 2. the optical signal is a binary intensity modulated signal;
A communication system according to any one of claims 1 to 3. A processing method executed by a communication system including a transmitting device and a receiving device,
The transmitting device
Synchronizing the time with the receiving device;
Controlling encryption of optical signals based on rules set for each of a plurality of periods indicated by the time;
generating an encrypted optical signal for each of the plurality of time periods based on the control;
transmitting the encrypted optical signal to the receiving device during one of the plurality of time periods;
Run
The receiving device
Synchronizing the time with the transmitting device;
receiving the encrypted optical signal during the one period of time;
converting the received encrypted optical signal into an electrical signal;
decoding the electrical signal based on a rule set for each of the plurality of periods;
To execute
Processing method. a synchronization means for synchronizing the time with a receiving device of a communication target;
a control means for controlling encryption of an optical signal based on a rule set for each of a plurality of periods indicated by the time;
a generating means for generating an encrypted optical signal for each of the plurality of periods under control of the control means;
a transmitting means for transmitting the encrypted optical signal to the receiving device during one of the plurality of periods;
A transmitting device comprising: Synchronizing the time with a receiving device that is a communication target;
Controlling encryption of optical signals based on rules set for each of a plurality of periods indicated by the time;
generating an encrypted optical signal for each of the plurality of time periods based on the control;
transmitting the encrypted optical signal to the receiving device during one of the plurality of time periods;
A processing method comprising: On the computer,
Synchronizing the time with a receiving device that is a communication target;
Controlling encryption of optical signals based on rules set for each of a plurality of periods indicated by the time;
generating an encrypted optical signal for each of the plurality of time periods based on the control;
transmitting the encrypted optical signal to the receiving device during one of the plurality of time periods;
A program that executes the following. a synchronization means for synchronizing the time with a transmitting device as a communication target;
a receiving means for receiving, during one period of a plurality of periods indicated by the time, an optical signal encrypted by the transmitting device;
a conversion means for converting the encrypted optical signal received by the receiving means into an electrical signal;
a decoding means for decoding the electrical signal based on a rule set for each of the plurality of periods;
A receiving device comprising: Synchronizing the time with a transmitting device to be communicated with;
receiving, during one period of a plurality of periods indicated by the time, an optical signal encrypted by the transmitting device during the one period;
converting the received encrypted optical signal into an electrical signal;
decoding the electrical signal based on a rule set for each of the plurality of periods;
A processing method comprising: On the computer,
Synchronizing the time with a transmitting device to be communicated with;
receiving, during one period of a plurality of periods indicated by the time, an optical signal encrypted by the transmitting device during the one period;
converting the received encrypted optical signal into an electrical signal;
decoding the electrical signal based on a rule set for each of the plurality of periods;
A program that executes the following.