阅读说明：本技术 随机数生成电路和随机数生成方法 (Random number generation circuit and random number generation method ) 是由 上里敦 于 2018-11-21 设计创作，主要内容包括：[问题]提供一种随机数生成电路,在不需要更复杂的电路配置的情况下利用该随机数生成电路能够获得难以预测的随机数。[解决方案]此随机数生成电路被配置成包括光输出装置(1)、光接收装置(2)、电流/电压转换装置(3)、比较装置(4)、采样装置(5)和输出装置(6)。光输出装置(1)输出规定波长的光。光接收装置(2)接收光并将其转换成电流信号。电流/电压转换装置(3)将电流信号转换成电压信号。比较装置(4)将电压信号与参考电压进行比较,并将电压信号转换成二进制信号。采样装置(5)以基于光噪声频率而设置的周期对由比较装置(4)转换的二进制信号采样,并将其转换成位数据。输出装置(6)输出以位数据的转换顺序排列的位串数据。([ problem ] to provide a random number generation circuit with which a random number that is difficult to predict can be obtained without requiring a more complicated circuit configuration. [ solution ] this random number generation circuit is configured to include light output means (1), light receiving means (2), current/voltage conversion means (3), comparison means (4), sampling means (5), and output means (6). The light output device (1) outputs light of a predetermined wavelength. The light receiving device (2) receives light and converts it into a current signal. The current/voltage conversion means (3) converts the current signal into a voltage signal. The comparison device (4) compares the voltage signal with a reference voltage and converts the voltage signal into a binary signal. The sampling means (5) samples the binary signal converted by the comparison means (4) at a period set based on the optical noise frequency and converts it into bit data. An output device (6) outputs bit string data arranged in the conversion order of the bit data.)

1. A random number generation circuit, comprising:

a light output device for outputting light of a prescribed wavelength;

a light receiving device for receiving light and converting the light into a current signal;

current/voltage conversion means for converting the current signal into a voltage signal;

comparing means for converting the voltage signal into a binary signal by comparison with a reference voltage;

sampling means for sampling the binary signal converted by the comparing means at a period set based on a frequency of noise of the light and converting the sampled signal into bit data; and

output means for outputting bit string data in which the bit data are arranged in the converted order.

2. The random number generation circuit of claim 1, further comprising:

separating means for separating the binary signal converted by the comparing means into a first path and a second path; and

inverting means for inverting a potential of the binary signal in the second path and outputting the inverted potential, wherein

The sampling means alternately samples the binary signal input from the first path and the binary signal inverted and input from the second path.

3. The random number generation circuit according to claim 1 or 2, further comprising reference voltage setting means for setting the reference voltage based on a binary ratio of the bit data sampled by the sampling means.

4. The random number generation circuit according to any one of claims 1 to 3, further comprising monitoring means for monitoring whether the bit data sampled by the sampling means is randomly generated.

5. The random number generation circuit of any of claims 1 to 4, further comprising:

a light monitoring device for monitoring the light output by the light output device; and

control means for controlling the light output means in such a manner that the power of the light becomes constant.

6. The random number generation circuit according to any one of claims 1 to 5, wherein the output means outputs information of the state of the bit string as a random number to a request source based on an external request.

7. A random number generation system, comprising:

the random number generation circuit according to any one of claims 1 to 6; and

an operation processing device that performs processing by using bit string data as a random number, wherein

The operation processing means performs processing using the bit string data acquired from the random number generation circuit as a random number.

8. A random number generation method, comprising:

outputting light of a prescribed wavelength;

receiving light and converting the light into a current signal;

converting the current signal to a voltage signal;

converting the voltage signal into a binary signal by comparison with a reference voltage;

sampling the converted binary signal at a period set based on a frequency of noise of the light and converting the sampled signal into bit data; and

outputting bit string data in which the bit data are arranged in the converted order.

9. The random number generation method of claim 8, further comprising:

separating the converted binary signal into a first path and a second path;

inverting a potential of the binary signal in the second path; and

the binary signal input from the first path and the binary signal inverted and input from the second path are alternately sampled.

10. The random number generation method according to claim 8 or 9, further comprising setting the reference voltage based on a binary ratio of the sampled bit data.

Technical Field

The present invention relates to a technique of generating random numbers, and particularly to a technique of generating random numbers based on output from a laser.

Background

With the development of information and communication technologies, the necessity of acquiring a large-number random number in encryption and the like has increased. Due to the development of big data analysis techniques and techniques related to Artificial Intelligence (AI), it has become important to acquire random numbers that are difficult to predict or estimate. Since processing such as encryption is performed in various devices, it is desirable that a random number generation circuit that generates random numbers have a configuration that is small in size and simplified as much as possible.

As a method of acquiring random numbers that are difficult to predict or estimate, there is a method of acquiring random numbers from a natural phenomenon with high contingency, instead of the pseudo-generated random numbers. As one of techniques for acquiring random numbers by using natural phenomena, there is a technique for acquiring random numbers based on light output from a laser. An example of such a technique of acquiring a random number based on light output from a laser is a technique as disclosed in patent document 1.

The random number generation circuit of PT L1 generates a random number based on light output from a chaotic laser oscillator including a laser and a mirror the chaotic laser oscillator of patent document 1 operates by reflecting light output from the laser by the mirror and thereby causing the light to be incident on the laser, the random number generation circuit of PT L1 generates a binary random number based on fluctuations in power output from the chaotic laser oscillator.

[ citation list ]

[ patent document ]

[ PT L1 ] Japanese unexamined patent application publication No.2009-

Disclosure of Invention

[ problem ] to

The random number generation circuit of PT L needs an optical path in which light output from a laser is reflected by a mirror and is thus incident on the laser in order to exhibit a function as a chaotic laser, and an optical path in which light output from the laser is received and converted into an electric signal.

In order to solve the above-described problems, it is an object of the present invention to provide a random number generation circuit that can acquire a random number that is difficult to predict without complicating the circuit configuration.

[ means for solving problems ]

In order to solve the above-described problems, a random number generation circuit according to the present invention includes light output means, light receiving means, current/voltage conversion means, comparison means, sampling means, and output means. The light output device outputs light of a predetermined wavelength. The light receiving device receives light and converts the light into a current signal. The current/voltage conversion means converts the current signal into a voltage signal. The comparison means converts the voltage signal into a binary signal by comparison with a reference voltage. The sampling means samples the binary signal converted by the comparing means at a period set based on the frequency of the noise of the light, and converts the sampled signal into bit data. The output device outputs bit string data in which bit data is arranged in the converted order.

The random number generation method according to the present invention includes: outputting light of a prescribed wavelength; receiving light; converting the light into a current signal; converting the current signal into a voltage signal; and converting the voltage signal into a binary signal by comparing with a reference voltage. The random number generation method according to the present invention further includes: sampling the converted binary signal at a period set based on a frequency of the noise of the light, and converting the sampled signal into bit data; and outputting bit string data in which the bit data is arranged in the converted order.

[ advantageous effects of the invention ]

According to the present invention, a random number that is difficult to predict can be acquired without complicating the circuit configuration.

Drawings

Fig. 1 is a diagram illustrating an outline of the configuration of the first exemplary embodiment of the present invention.

Fig. 2 is a diagram illustrating an outline of the configuration of the second exemplary embodiment of the present invention.

Fig. 3 is a diagram illustrating the configuration of a control unit of the second exemplary embodiment of the present invention.

Fig. 4 is a diagram illustrating an example of a configuration of a random number generation system according to a second exemplary embodiment of the present invention.

Fig. 5 is a graph illustrating an example of a relationship between power and current of light output by a laser diode in the second exemplary embodiment of the present invention.

Fig. 6 is a diagram illustrating an example of filter characteristics in the second exemplary embodiment of the present invention.

Fig. 7 is a diagram illustrating an example of characteristics of a current/voltage conversion circuit in the second exemplary embodiment of the present invention.

Fig. 8 is a diagram illustrating an example of sampling timing in the second exemplary embodiment of the present invention.

Fig. 9 is a diagram illustrating an example of the relationship between the amplitude of the voltage signal and the detection frequency in the second exemplary embodiment of the present invention.

Fig. 10 is a diagram illustrating an example of input signals and output signals of a sampling unit in the second exemplary embodiment of the present invention.

Detailed Description

[ example embodiments ]

(first exemplary embodiment)

A first exemplary embodiment of the present invention is described in detail with reference to the accompanying drawings. Fig. 1 illustrates an outline of the configuration of a random number generation circuit according to the present exemplary embodiment. The random number generation circuit according to the present exemplary embodiment includes a light output device 1, a light receiving device 2, a current/voltage conversion device 3, a comparison device 4, a sampling device 5, and an output device 6. The output device 1 outputs light of a predetermined wavelength. The light receiving device 2 receives light and converts the light into a current signal. The current/voltage conversion means 3 converts the current signal into a voltage signal. The comparison means 4 convert the voltage signal into a binary signal by comparison with a reference voltage. The sampling means 5 samples the binary signal converted by the comparison means 4 at a period set based on the noise frequency of light, and converts the sampled signal into bit data. The output device 6 outputs bit string data in which bit data are arranged in the converted order.

In the random number generation circuit according to the present exemplary embodiment, light output from the light output device 1 is received and converted into a current signal by the light receiving device 2, and converted into a voltage signal by the current/voltage conversion device 3. In the random number generation circuit according to the present exemplary embodiment, a binary signal converted from a voltage signal by the comparison means 4 is sampled at a period set based on the frequency of noise of light, and the binary signal is converted into bit data by the sampling means 5. Therefore, the random number generation circuit according to the present exemplary embodiment samples the voltage signal converted from light at a period set at a frequency based on the noise of light, and thereby can output a random number without complicating the circuit configuration.

(second example embodiment)

A second exemplary embodiment of the present invention is described in detail with reference to the accompanying drawings. Fig. 2 illustrates an outline of the configuration of the random number generation circuit according to the present exemplary embodiment. The random number generation circuit 100 according to the present exemplary embodiment includes an optical module 10, a control unit 20, a comparison unit 31, a sampling unit 32, an inversion unit 33, a current/voltage conversion unit 34, and an a/D conversion unit 35. The random number generation circuit 100 is connected to a Central Processing Unit (CPU), and outputs data of the generated random number and information on a light state on which the random number is based to the CPU.

The optical module 10 further includes a light output unit 11, an optical wavelength filter unit 12, a light receiving unit 13, a monitoring light receiving unit 14, a temperature adjusting unit 15, and a temperature monitoring unit 16. The light output unit 11, the optical wavelength filter unit 12, the light receiving unit 13, and the monitoring light receiving unit 14 of the optical module 10 are formed on the same plate, and are fixed so as not to be displaced in the optical system. All parts of the optical module 10 are accommodated in the housing.

The light output unit 11 includes a laser diode and a current source that supplies current to the laser diode, and outputs light having a prescribed wavelength. The power of the light output by the light output unit 11 is controlled by the current value supplied by the current source. The current value of the current supplied by the current source is set based on the current control signal S11 sent from the control unit 20. The light output from the light output unit 11 is input to the optical wavelength filter unit 12. The configuration may be made in such a manner that a current source is provided outside the optical module 10, and current is supplied from the current source to a laser diode inside the optical module 10.

The wavelength of light output by the light output unit 11 may be corrected based on the wavelength of light measured by the monitoring light receiving unit 14. With this configuration, a light output module capable of changing the wavelength is used in the light output unit 11. Correcting the wavelength of the light output by the light output unit 11 based on the wavelength of the light measured by the monitoring light receiving unit 14 achieves continuous acquisition of high-quality random numbers even when the wavelength characteristics change due to aging or temperature variation.

The optical wavelength filter unit 12 is provided as a band-pass filter that allows light of a prescribed wavelength input from the optical output unit 11 to pass therethrough. An example that can be used as the optical wavelength filter unit 12 is a dielectric multilayer filter. The light to which the filtering process has been applied in the optical wavelength filter unit 12 is separated and input to the light receiving unit 13 and the monitoring light receiving unit 14.

The light receiving unit 13 includes a photodiode, and converts light input from the optical wavelength filter unit 12 into a current signal. A DC bias circuit is connected to the photodiode and a bias voltage is applied to the photodiode. The current signal converted from light by the light receiving unit 13 is input to the current/voltage converting unit 34 as a current signal S15. In the case of a configuration in which the wavelength of light of the light output unit 11 is corrected, information indicating the correction state is transmitted to the CPU via the control unit 20, and the CPU is notified that the function of the light output unit 11 is normal.

The monitoring light receiving unit 14 measures the wavelength of light input from the optical wavelength filter unit 12, and acquires data for monitoring the deviation of the wavelength of light having passed through the optical wavelength filter unit 12 from a set value. The monitor light-receiving unit 14 includes a monochromator, and measures the spectrum of input light. Based on the spectrum of light measured by the monitoring light-receiving unit 14, the wavelength at which the power of the detected light reaches its peak value is detected, and the wavelength of the input light is thereby specified. The monitoring light-receiving unit 14 outputs information of the spectrum of the measured light to the control unit 20 as a monitoring result signal S16.

The temperature adjusting unit 15 includes a function of maintaining the temperature inside the optical module 10 at a set temperature. The temperature adjusting unit 15 includes a Peltier (Peltier) element, and adjusts the temperature inside the optical module 10 in such a manner as to become a set temperature. The temperature adjusting unit 15 operates based on the temperature control signal S12 sent from the control unit 20, and thereby heats or cools the inside of the housing of the optical module 10.

The temperature monitoring unit 16 measures the temperature inside the optical module 10, and sends the measured temperature data as a temperature measurement signal S13 to the control unit 20.

The configuration of the control unit 20 is described below. Fig. 3 illustrates an overview of the configuration of the control unit 20 of the present exemplary embodiment. The control unit 20 includes a light output control unit 21, a sampling control unit 22, a temperature control unit 23, a comparison verification unit 24, and an output unit 25. The connection between the units of the control unit 20 is performed through a bus. The control unit 20 is constituted by a semiconductor device such as a Central Processing Unit (CPU) or a Field Programmable Gate Array (FPGA).

The light output control unit 21 controls the power of the light output by the light output unit 11 so that the average value of the power of the light received by the light receiving unit 13 becomes a set value. Based on the light power value input from the a/D conversion unit 35 as the digital conversion signal S22, the light output control unit 21 determines the increase or decrease value of the current value in the light output unit 11 in such a manner that the power of the light received by the light receiving unit 13 becomes constant. The light output control unit 21 sends information of the current value of the light output unit 11 set in such a manner that the power of the light received by the light receiving unit 13 becomes constant to the light output unit 11 as a current control signal S11

When the comparison unit 31 determines "low" or "high", the sampling control unit 22 sends an analog signal of a reference voltage serving as a reference to the comparison unit 31 as the threshold voltage signal S14. The sampling control unit 22 changes the ratio of "low" to "high" of the signal input as the sampling result signal S19 to 1: the way of 1 determines the reference voltage used as the threshold. The sampling control unit 22 sends a clock indicating the sampling period in the sampling unit 32 to the sampling unit 32 as a sampling period signal S17.

The sampling period is set depending on the period of noise of light output from the laser diode of the light output unit 11 and the circuit frequency characteristic of the optical/electrical conversion. The sampling period may be variable depending on the ratio of "low" and "high" of the signal sampled by the sampling unit 32.

The temperature control unit 23 controls the temperature adjustment unit 15 so that the temperature inside the optical module 10 becomes a set value. The temperature control unit 23 determines the increase or decrease value of the temperature based on the temperature data sent from the temperature monitoring unit 16 as the temperature measurement signal S13. The temperature control unit 23 generates a signal indicating the set temperature for the temperature adjusting unit 15 based on the increase or decrease value of the temperature, and sends the generated signal to the temperature adjusting unit 15 as a temperature control signal S12.

The comparison verification unit 24 monitors the data input from the sampling unit 32 as the sampling result signal S19, determines whether the generated random numbers are statistically suitable, and generates information of the determination result as quality data. For example, the comparative verification unit 24 confirms the quality of the random numbers by performing a random number test based on NIST SP800-22 defined by National Institute of Standards and Technology (NIST) of the U.S. department of commerce. The quality data is constituted by, for example, an index indicating whether the random number is statistically appropriate.

The comparison verification unit 24 determines a deviation from a prescribed wavelength set as the wavelength output by the optical output unit 11 based on the data of the light wavelength transmitted from the monitoring light receiving unit 14 as the monitoring result signal S16. The comparison verification unit 24 adds the wavelength of light received by the monitoring light receiving unit 14 or the deviation amount from the prescribed wavelength to the quality data, and transmits the quality data to the output unit 25.

The output unit 25 outputs bit string data generated as data for a random number as an output signal S100 to an external CPU or the like that performs processing such as encryption using the random number. In response to a request transmitted as a request signal S200 from the CPU or the like, the output unit 25 outputs the quality data generated by the comparison verification unit 24 to the CPU or the like as an output signal S100.

The comparison unit 31 includes a function of comparing the input signal and outputting the comparison result as a comparison result signal S18. The comparison unit 31 is constituted by using a comparator. The comparing unit 31 compares the voltage of the signal input as the threshold voltage signal S14 from the sampling control unit 22 with the voltage of the signal input as the voltage signal S21 from the current/voltage converting unit 34. If the voltage signal S21 is greater than the threshold voltage signal S14, the comparison unit 31 outputs a "high" signal as the comparison result signal S18. When the voltage of the voltage signal S21 is equal to or lower than the voltage of the threshold voltage signal S14, the comparison unit 31 outputs a "low" signal as the comparison result signal S18. The signal output from the comparison unit 31 is split into two paths, one of the split signals is directly input to the sampling unit 32, and the other of the split signals is input to the sampling unit 32 via the inversion unit 33.

The inverting unit 33 inverts the signal input as the comparison result signal S18 and outputs the inverted signal. The inverting unit 33 is constituted by using an inverter. The inverting unit 33 converts the input "high" signal into a "low" signal, converts the input "low" signal into a "high" signal, and outputs the inverted signal as the inverted signal S20. The inverting unit 33 sends the inverted signal to the sampling unit 32 as an inverted signal S20.

The current/voltage converting unit 34 is configured as a current/voltage converting circuit that converts the input current signal S15 into a voltage signal and outputs the voltage signal as a voltage signal S21.

The a/D conversion unit 35 converts an analog signal input as the voltage signal S21 from the current/voltage conversion unit 34 into a digital signal, and outputs the digital signal to the control unit 20 as the digital conversion signal S22. The a/D conversion unit 35 outputs the voltage value information of the voltage signal S21 input from the current/voltage conversion unit 34 to the control unit 20 as a digital conversion signal S22 in the form of a digital signal.

Fig. 4 illustrates a configuration example of a random number generation system constituted by the random number generation circuit 100 and the CPU 200 according to the present exemplary embodiment. The CPU 200 transmits a signal requesting data of a random number or information of a generation state of the random number to the random number generation circuit 100 as a request signal S200. In response to the request signal S200, the random number generation circuit 100 transmits data of the random number or information of the generation state of the random number as the output signal S100. The CPU 200 executes each processing item such as encryption by using the bit string data acquired from the random number generation circuit 100 as a random number. The CPU 200 requests quality data from the random number generation circuit 100 and receives the quality data as a response, thereby monitoring the generation state of the random number in the random number generation circuit 100.

The operation of the random number generation circuit according to the present exemplary embodiment is described below. When the random number generation circuit 100 starts operating, the light output control unit 21 of the control unit 20 sends a signal indicating the current value applied to the laser diode by the current source as the current control signal S11 to the light output unit 11 of the optical module 10. An initial value of a current value supplied to the laser diode by the current source is set in advance. As an initial value of the current supplied to the laser diode by the current source, a value set at the time of the last operation may be stored and used.

Upon receiving the current control signal S11, the light output unit 11 supplies a current of a current value indicated by the current control signal S11 from a current source to the laser diode, and outputs continuous light of a preset wavelength. Fig. 5 illustrates an example of a relationship between a current flowing through the laser diode and the power of output light in the light output unit 11.

The light output from the light output unit 11 is input to the optical wavelength filter unit 12. When light is input, the optical wavelength filter unit 12 applies filtering processing, and thereby allows only light in a set frequency band to pass through. The optical wavelength filter unit 12 separates the light to which the filtering process has been applied into two parts, and outputs the two parts to the light receiving unit 13 and the monitoring light receiving unit 14.

Fig. 6 illustrates an example of the filter characteristic of the optical wavelength filter unit 12. The horizontal axis of fig. 6 indicates the frequency of light, and the vertical axis indicates the transmittance of light of each frequency. The wavelength of light transmitted through the optical wavelength filter unit 12 is set in such a manner as to be adjusted to the wavelength of light output by the light output unit 11.

When light is input to the monitoring light receiving unit 14, the monitoring light receiving unit 14 measures the spectrum of the input light, and sends the measurement result as a monitoring result signal S16 to the comparison verification unit 24 of the control unit 20.

The light input to the light receiving unit 13 is converted into a current signal by the photodiode, and is sent to the current/voltage converting unit 34 as a current signal S15.

When the current signal S15 is input, the current/voltage conversion unit 34 converts the input current signal into a voltage signal, and outputs the converted voltage signal as a voltage signal S21. The voltage signal S21 output from the current/voltage conversion unit 34 is split into two paths and sent to the comparison unit 31 and the a/D conversion unit 35.

Fig. 7 is a diagram illustrating an example of the characteristics of the current/voltage conversion circuit in the current/voltage conversion unit 34 of the random number generation circuit 100. Fig. 7 is a graph illustrating conversion efficiency from current to voltage for each frequency. In fig. 7, the horizontal axis indicates the frequency of the electric signal, and the vertical axis indicates the conversion efficiency from current to voltage when the current values of the input current signals are the same.

The signal input to the a/D conversion unit 35 as the voltage signal S21 is converted into a digital signal, and information of the voltage value of the input voltage signal S21 is input to the light output control unit 21 of the control unit 20 as the digital conversion signal S22.

When the voltage signal S21 is input to the comparison unit 31, the comparison unit 31 compares the voltage of the voltage signal S21 with the voltage of the threshold voltage signal S14 input as a signal indicating a reference voltage from the sampling control unit 22 of the control unit 20.

When the voltage of the voltage signal S21 is higher than the reference voltage, the comparison unit 31 outputs a "high" signal. When the voltage of the voltage signal S21 is equal to or lower than the reference voltage, the comparison unit 31 outputs a "low" signal as the comparison result signal S18. The comparison result signal S18 output from the comparison unit 31 is split into two parts, one of the two parts is directly input to the sampling unit 32, and the other of the two parts is input to the inversion unit 33.

Fig. 8 illustrates an example of a signal input to the comparator of the comparison unit 31. Symbol V in FIG. 8_compIndicating a reference voltage. In fig. 8, the horizontal axis indicates time when sampling is performed, and the vertical axis indicates the voltage of the input signal.

FIG. 9 illustrates the relationship between the amplitude of the input signal of the sampling unit 32 and the frequency of occurrence for each amplitude, hi FIG. 9, "H output" corresponds to a "high" signal, and "L output" corresponds to a "low" signal, as illustrated in FIG. 9, by appropriately setting the reference voltage V_compIt is desirable to detect "high" and "low" at nearly the same frequency.

When the comparison result signal S18 is input, the inverting unit 33 inverts between "high" and "low" of the potential of the input signal, and outputs the inverted signal to the sampling unit 32 as the inverted signal S20.

When the comparison result signal S18 and the inverted signal S20 are input, the sampling unit 32 samples the input signal. The sampling unit 32 distinguishes "high" and "low" of the signals input from the comparison result signal S18 and the inverted signal S20, and alternately samples the signals input from the comparison result signal S18 and the inverted signal S20. The sampling unit 32 samples the input signal based on a signal indicating sampling timing transmitted from the control unit 20 as a sampling period signal S17.

Fig. 10 illustrates a relationship between the states of the comparison result signal S18 and the inverted signal S20 and the signal output from the sampling unit 32. In fig. 10, "comparison unit output" indicates the state of the comparison result signal S18 input from the comparison unit 31 to the sampling unit 32. In fig. 10, "inverting unit output" indicates the state of the inverted signal S20 input from the inverting unit 33 to the sampling unit 32. In fig. 10, "output of sampling unit" indicates the state of sampling result signal S19 output from sampling unit 32. In fig. 10, the comparison result signal S18 and the inverted signal S20 are alternately sampled and output from the sampling unit 32.

The sampling period is set based on a period of controlling the power of light in the light output unit 11, characteristics of the light receiving unit 13 and the current/voltage conversion unit 34, and the like. The sampling period is set, for example, to be shorter than the period for controlling the optical power of the optical output unit 11 in a manner not affected by the control period. The sampling period is set within a range of a period in which optical/electrical conversion in the light receiving unit 13 can respond, and within a range of the frequency characteristic of the current/voltage converting unit 34. The configuration is made in such a manner that the sampling period is set to be variable based on the generation state of the random number. In such a configuration, for example, when the reference voltage is set in the sampling control unit 22, the control unit 20 may be configured in such a manner that the sampling period is determined based on the occurrence rate of "high" and "low".

The sampling unit 32 generates bit string data in which the sampling bit data is arranged in the sampling order, and sends the generated bit string data to the comparison verification unit 24 of the control unit 20 as a sampling result signal S19.

Upon receiving the sampling result signal S19, the output unit 25 of the control unit 20 outputs the received bit string data as data of a random number to the CPU 200.

The comparison verification unit 24 of the control unit 20 analyzes the sampling result signal S19, determines whether the generated random number, which is data of the random number, is statistically appropriate, and generates information of the determination result as quality data. The control unit 20 transmits the generated quality data to the CPU 200 based on a request of the CPU 200. By repeating the above-described operations, the random number generation circuit 100 can supply data for generating a random number to the CPU 200.

The light output control unit 21 of the control unit 20 controls the power of light output from the light output unit 11 while generating the above-described data for generating random numbers. Based on the information of the light power of the light receiving unit 13 input as the digital conversion signal S22, the control unit 20 controls the light output from the light output unit 11 in such a manner that the average value of the power of the light received by the light receiving unit 13 becomes constant. By performing control in such a manner that the average value of the powers of the light received by the light receiving unit 13 becomes a set value, a high-quality random number can be generated based on fluctuations in the power of the light. The control unit 20 stores in advance information of the filter characteristic and the splitting ratio of the optical wavelength filter unit 12, and information of the relationship between the amount of change in light in the light receiving unit 13 and the amount of adjustment of the power of light output by the light output unit 11. The control unit 20 generates a control signal that adjusts the power of the light output by the light output unit 11, and sends the generated control signal to the light output unit 11 as a current control signal S11. The control unit 20 controls the light output unit 11 by Automatic Power Control (APC) in such a manner that the average value of the powers of the light received by the light receiving unit 13 becomes a reference value set in advance. The light output unit 11 adjusts the power of the output light based on the current control signal S11, and thereby the power of the light received by the light receiving unit 13 is kept constant.

The temperature control unit 23 of the control unit 20 controls the temperature inside the optical module 10 while generating the above-described data for generating random numbers. When the random number generation circuit 100 is operating, the temperature monitoring unit 16 of the optical module 10 measures the temperature inside the optical module 10, and sends information of the measured temperature as a temperature measurement signal S13 to the temperature control unit 23 of the control unit 20. Based on the information of the temperature inside the optical module 10 input as the temperature measurement signal S13 from the temperature monitoring unit 16, the temperature control unit 23 controls the temperature adjustment unit 15 in such a manner that the temperature inside the optical module 10 becomes a set value. The temperature control unit 23 sends a control signal indicating the adjustment amount of the temperature adjustment unit 15 to the temperature adjustment unit 15 as a temperature control signal S12. The temperature adjusting unit 15 changes the temperature of the peltier element based on the temperature control signal S12, thereby adjusting the temperature inside the optical module 10. The temperature adjusting unit 15 maintains the temperature inside the optical module 10 at a set value, thereby stabilizing the wavelength and power of the light output from the light output unit 11.

While generating the above-described data for generating random numbers, the sampling control unit 22 monitors bit string data of samples based on the sampling result signal S19. The sampling control unit 22 determines the reference voltage in the comparison unit 31 based on the monitoring result. The sampling control unit 22 adjusts the reference voltage in such a manner that the occurrence rate of "high" and "low" becomes 1: 1. The sampling control unit 22 calculates the occurrence rates of "high" and "low" based on a prescribed time or a prescribed amount of data. When the occurrence rate of "high" is high, the sampling control unit 22 sets the reference voltage in such a manner as to become higher. When the occurrence rate of "low" is high, the sampling control unit 22 sets the reference voltage in such a manner as to become lower. When a new reference voltage is set, the sampling control unit 22 outputs a signal indicating the newly set reference voltage to the comparison unit 31 as the threshold voltage signal S14. The threshold voltage signal S14 is converted into an analog signal and output. A unit for converting into an analog signal may be provided outside the control unit 20.

While the above-described data for generating random numbers is generated, the comparison verification unit 24 of the control unit 20 monitors the light output from the light output unit 11 in addition to generating the quality data of the data for random numbers. The comparison verification unit 24 monitors the deviation between the wavelength of light included in the monitoring result signal S16 and the wavelength of light set in advance, and generates information of the deviation of the wavelength. The comparison verification unit 24 extracts information of the power of the light included in the monitoring result signal S16. The comparison and verification unit 24 transmits information of the deviation of the wavelength and power of the light to the output unit 25. In response to a request of the CPU 200, the output unit 25 transmits information of the deviation of the wavelength and power of the light to the CPU 200 as an output signal S100.

The random number generation circuit 100 according to the present exemplary embodiment samples the voltage signal converted from light in the sampling unit 32 at a sampling period based on the period of noise of light output from the light output unit 11. Since the reference voltage at the time of sampling is set in such a manner that the detection ratio of "high" and "low" becomes 1:1, a random number with high contingency based on optical noise can be acquired.

The random number generation circuit 100 according to the present exemplary embodiment separates the output from the comparator of the comparison unit 31 into two parts, and inverts one of the two parts in the inverter of the inversion unit 33. For the two separated signals, the random number generation circuit 100 according to the present exemplary embodiment alternately samples the non-inverted signal and the inverted signal in the sampling unit 32. Sampling in this way brings the ratio of "high" to "low" of the sampled signal closer to 1:1, thereby improving the quality of the random number.

The random number generation circuit 100 according to the present exemplary embodiment verifies the quality of the random number, and outputs the verification result and information of the optical state on which the random number is based to the CPU 200. Outputting the verification result of the random number quality enables the CPU 200 to grasp the quality of the random number and the soundness of the light output unit 11 as a generation source of the random number using the random number and use the quality and soundness in processing such as encryption.

In the random number generation circuit 100 according to the present exemplary embodiment, the random number sequence acquired by the comparison verification unit 24 may be scrambled by a linear feedback shift register or the like. With this configuration, randomness can be further improved, and random numbers of stable quality can be acquired.

As described above, the random number generation circuit 100 according to the present exemplary embodiment can provide a random number that is based on a natural phenomenon and is difficult to predict, and a verification result of the quality of the random number, without complicating the circuit configuration.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, the present invention is not limited to these embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

The present application is based on and claims priority from japanese patent application No.2017-228299, filed on 28.11.2017, the entire contents of which are incorporated herein by reference.

[ list of reference signs ]

1 light output device

2 light receiving device

3 current/voltage conversion device

4 comparing device

5 sampling device

6 output device

10 optical module

11 light output unit

12 optical wavelength filter unit

13 light receiving unit

14 monitoring light receiving unit

15 temperature regulating unit

16 temperature monitoring unit

20 control unit

21 light output control unit

22 sampling control unit

23 temperature control unit

24 comparison verification unit

25 output unit

31 comparing unit

32 sampling unit

33 inverting unit

34 current/voltage conversion unit

35A/D conversion unit

100 random number generation circuit

200 CPU

S11 Current control Signal

S12 temperature control signal

S13 temperature measurement signal

S14 threshold Voltage Signal

S15 Current Signal

S16 monitoring result signal

S17 sampling periodic signal

S18 comparing the resulting signals

S19 sampling result signal

S20 inverted signal

S21 Voltage Signal

S22 digital conversion signal

S100 output signal

S200 request signal