JP7359683B2 - random number generator - Google Patents

Description

The present invention relates to a random number generator.

Cryptography is used for information security, but cryptography often requires random numbers. For example, the encryption key used for encryption is generally a random number. Random numbers must not be predicted or reproduced by anyone. As a random number generation technique, for example, a technique is known in which a ring oscillator is sampled and used as a random number source (see Patent Document 1). There is also a random number generation IC that generates random numbers from the thermal noise of a semiconductor such as a Zener diode.

Patent No. 5465636 Patent No. 5292797

However, in the above-mentioned technique, in order to obtain random numbers, a computer equipped with a random number generation device or a random number generation IC is used, which poses a problem of increased cost. Furthermore, in products that are required to have low power consumption, such as battery-powered products, an increase in current consumption in a random number generator added to generate random numbers becomes a problem.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to enable random numbers to be generated without causing an increase in cost or current consumption.

The random number generation device according to the present invention includes a time measurement section configured to measure the time of a measurement target and output the measured value, and an operation configured to use the measured value outputted by the time measurement section as a random number. It is equipped with a section.

In one configuration example of the random number generator, the calculation unit extracts a numerical value with a set number of digits from the measured value and uses it as a random number. For example, the calculation unit extracts a numerical value of a set number of digits from the lowest order of the measured value and uses it as a random number.

In one configuration example of the random number generator, the arithmetic unit combines a plurality of numerical values extracted from each of the plurality of measurement values to generate a random number.

In one configuration example of the random number generator, the measured value is digital data.

In one configuration example of the random number generating device, the time measurement unit measures the time from when electromagnetic waves or sound waves are sent out from the transmitting unit to when they are reflected by a target object and received by the receiving unit.

As described above, according to the present invention, since the measured value outputted by the time measuring section is used as a random number, random numbers can be generated without causing an increase in cost or current consumption.

FIG. 1 is a configuration diagram showing the configuration of a random number generation device according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing the hardware configuration of the calculation unit 102 of the random number generation device according to the embodiment of the present invention.

Hereinafter, a random number generator according to an embodiment of the present invention will be described with reference to FIG. This random number generation device includes a time measurement section 101 that measures the time of a measurement target and outputs the measured value, and a calculation section 102 that uses the measured value outputted by the time measurement section 101 as a random number. The measured value is digital data. The time measurement unit 101 can be configured from, for example, a known time measurement circuit (Time to Digital Converter: TDC). The calculation unit 102 extracts a numerical value with a set number of digits from the measured value and uses it as a random number. For example, the calculation unit 102 extracts a numerical value with a set number of digits from the lowest value of the measured value and uses it as a random number. For example, invalid digits of the measurement value can be extracted as random numbers. The random numbers obtained in this way are true random numbers.

For example, the time measured by the time measurement unit 101, which has a high resolution of several picoseconds, includes various errors. This error appears in the lower digits (lower bits) of the measured value, so this is used as a random number source. For example, the calculation unit 102 extracts the lowest three digits of the measured value and uses it as a random number. Further, the calculation unit 102 combines a plurality of numerical values extracted from each of the plurality of measurement values to generate a random number. For example, if the required number of digits of the random number is 12, the 12-digit random number is obtained by combining four 3-digit random numbers obtained through four time measurements.

Here, the time measuring unit 101 measures the time from when an electromagnetic wave or a sound wave is sent out from the transmitting unit 103 until it is reflected by the target object 131 and received by the receiving unit 104. For example, the time measuring section 101, the calculating section 102, the transmitting section 103, and the receiving section 104 are ultrasonic flowmeters. The transmitter 103 and the receiver 104 are ultrasonic transceivers, and the object 131 is, for example, a fluid.

In the ultrasonic flowmeter, a transmitter 103 outputs ultrasonic waves, and a receiver 104 receives reflected ultrasonic waves. The propagation time of the ultrasonic wave at this time is measured by the time measurement unit 101, and the calculation unit 102 calculates the flow rate of the fluid based on the measured propagation time difference (Patent Document 2). In this type of ultrasonic flowmeter, in order to remove error components, the forward and reverse propagation times are repeatedly measured and corrected, and the flow rate is calculated from the difference between the forward and reverse propagation times. In this way, in an ultrasonic flowmeter that measures time, random numbers can be generated without adding a new random number generation device or random number generation IC. Further, the random numbers obtained by the calculation unit 102 are stored in the storage unit 105 and used when necessary.

Further, the time measuring section 101, the calculating section 102, the transmitting section 103, and the receiving section 104 can also be a distance measuring device. The transmitter 103 emits a laser beam, and the receiver 104 receives the laser beam reflected by the object. The time measuring unit 101 measures the time from when the transmitting unit 103 emits the laser beam to when the laser beam is reflected by the object 131 and received by the receiving unit 104 . Based on the measured time difference, the calculation unit 102 calculates the distance from the transmission unit 103 to the target object 131.

Here, random numbers will be explained. Generally, random numbers include true random numbers and pseudorandom numbers. True random numbers are generated from physical phenomena such as thermal noise, light scattering, and radiation from atomic decay, and are numbers whose next value is independent of a known value. Pseudo-random numbers are calculated numbers that have properties similar to true random numbers. Pseudo-random numbers have a fixed calculation method, so if the internal state is known, the next value can be predicted. In addition, pseudo-random numbers may need to be initialized (seed) with true random numbers so that internal states cannot be identified.

Furthermore, random numbers are used, for example, to generate codes. For example, the encryption key is generated using a random number. For example, a Cryptographically Secure Pseudo Random Number Generator (CSPRNG) is used to generate cryptographic keys. Random numbers generated by a cryptographic pseudorandom number generator are unpredictable and reproducible, but because the calculation method is constant, the same value is generated from the same initial state. Therefore, in a cryptographic pseudo-random number generator, it is necessary to initialize the initial state with true random numbers.

Note that, as shown in FIG. 2, the calculation unit 102 of the random number generation device according to the embodiment described above is connected to a CPU (Central Processing Unit) 301, a main storage device 302, and an external storage device 303 via a network. The above-described operation of the arithmetic unit 102 may be realized by using a computer device including the device 304 and the like, and by causing the CPU 301 to operate (execute the program) according to a program developed in the main storage device 302. can. Network connection device 304 connects to network 305 . Also, each function can be distributed among multiple computer devices.

Further, the calculation unit 102 of the random number generator according to the embodiment described above can also be configured by a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

As described above, according to the present invention, since the measured value output by the time measuring section is used as a random number, random numbers can be generated without causing an increase in cost or current consumption.

It should be noted that the present invention is not limited to the embodiments described above, and many modifications and combinations can be made within the technical idea of the present invention by those having ordinary knowledge in this field. That is clear.

DESCRIPTION OF SYMBOLS 101... Time measurement part, 102... Calculation part, 103... Transmission part, 104... Receiving part, 105... Storage part, 131... Target object.

Claims (6)

a time measuring unit configured to measure the time of the measurement target in units of several picoseconds and output the measured value;
and an arithmetic unit configured to use, as a random number, a lower-order invalid digit that includes an error in the measurement value output by the time measurement unit. The random number generator according to claim 1,
The random number generation device, wherein the arithmetic unit extracts a numerical value with a set number of digits from the measured value and uses it as a random number. The random number generator according to claim 2,
The random number generating device, wherein the arithmetic unit extracts a numerical value of a set number of digits from the lowest order of the measured value and uses it as a random number. The random number generator according to claim 2 or 3,
A random number generation device, wherein the calculation unit combines a plurality of numerical values extracted from each of the plurality of measurement values to generate a random number. The random number generator according to any one of claims 1 to 4,
A random number generator, wherein the measured value is digital data. The random number generator according to any one of claims 1 to 5,
The random number generation device is characterized in that the time measurement unit measures the time from when an electromagnetic wave or a sound wave is sent out from a transmitting unit until it is reflected by an object and received by a receiving unit.

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