JP2003150374A - Random number generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a random number generator at low costs seeking out quickness together with safety. SOLUTION: The random number generator 1 using random events of electric noise is provided with a noise source, an amplifier that amplifies the noise, a reference pulse signal, a pulse width modulation circuit 3 that randomly varies pulse width according to noise levels on the basis of the reference pulse signal, and a random number generation circuit 6 that generates random number data 'zero' or '1' by contrasting states of 'zero', '1' of output pulses of the pulse width modulation circuit 3 with states of 'zero', '1' of the reference pulse signal. The pulse width modulation circuit 3 is constituted of a saw tooth wave generating part that generates saw tooth waves and a voltage comparator that compares voltage of the saw tooth waves and voltage of the amplified noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a random number generator utilizing a random event such as white noise (thermal noise) generated from an active circuit element, and particularly, it provides high speed, stability and low cost. It is related to the pursued random number generator.

[0002]

2. Description of the Related Art The use of random numbers is indispensable for advanced scientific computing, game machines, encryption processing, etc., and in recent years, high performance without regularity, correlation, or periodicity in the appearance of random numbers,
And the demand for high-speed true random number generators is increasing. As such a random number generator, for example, one using a random pulse obtained by using white noise generated from an active element such as a transistor or a diode in an electronic circuit or a passive element such as a resistor or a capacitor is known. As an example thereof, as disclosed in US-PATENT NO 6,61,702, a large number of VCOs used for random pulse generation with a noise source as an input and a plurality of VCO output sampling clocks operating asynchronously with each other are used. There is a random number generator composed of an oscillator and the like.

[0003]

However, since the random number generator according to the above disclosed technique contains many analog elements, there is a problem that the circuit configuration becomes complicated and large-scale, and the cost becomes expensive. There is. This is a major obstacle to the application to ultra-compact, thin and high-tech equipment, which is expected to be demanded in the future. In addition, in such a circuit configuration in which a large number of oscillators are simply provided, a plurality of oscillation outputs affect each other, and as a result, the appearance rate of random numbers tends to be biased, and the uniformity of random numbers may be impaired. .

Further, the circuit configuration utilizing a natural phenomenon such as so-called white noise is also susceptible to external noise, power supply fluctuation, temperature change, etc., and has a drawback of lacking operational stability.

The present invention has been made in view of the drawbacks of a random number generator using random pulses due to such a natural phenomenon, and provides an inexpensive random number generator that pursues stability and high speed. It is an object.

[0006]

That is, the present invention according to claim 1 is a random number for generating "0" or "1" of random number data by utilizing a random phenomenon of electrical noise such as white noise. A generator, a noise source, an amplifier that amplifies noise, a reference pulse signal, and a pulse width modulation circuit that randomly changes the pulse width according to the noise level with reference to the reference pulse signal, Random number generation for generating random number data "0" or "1" by comparing the "0" and "1" states of the output pulse of the pulse width modulation circuit with the "0" and "1" states of the reference pulse signal. It is characterized by having a circuit.

According to a second aspect of the present invention, in the random number generator according to the first aspect, the pulse width modulation circuit includes a sawtooth wave generating section for generating a sawtooth wave, and a voltage of the sawtooth wave. It is characterized by being configured with a voltage comparator for comparing noise voltage. With this configuration, a stable random number generation operation is obtained by setting the amplitude of the sawtooth wave so that noise always exists within the amplitude of the sawtooth wave with respect to fluctuations in the noise level due to power supply fluctuations, temperature changes, etc. The circuit configuration is also extremely simple.

According to a third aspect of the present invention, in the random number generator according to the second aspect, a plurality of sawtooth wave generators that generate sawtooth waves having different slopes are provided in parallel, and each sawtooth wave is provided. It is characterized in that a plurality of random number data are continuously generated with a time difference due to the difference in the slope of. As in this configuration, by using a plurality of sawtooth waves each having a different slope and gradually reducing the reference timing with noise, the slope of the sawtooth wave does not have to be increased (that is, the cycle of the sawtooth wave is not shortened. (Even) can generate multiple random pulses efficiently in a short time,
High-speed random number generation can be realized with a simple circuit configuration.

According to a fourth aspect of the present invention, in the random number generator according to the first aspect, the pulse width modulation circuit has an RC charging circuit whose charging time randomly changes according to noise voltage. However, it is characterized in that it is composed of pulse generation means for generating a pulse having a pulse width according to the charging time of the RC charging circuit.

According to a fifth aspect of the present invention, in the random number generator according to the fourth aspect, a monostable multivibrator is used as the pulse generating means. With the configurations of claims 4 and 5, the pulse width modulation circuit can be made extremely simple and stable operation can be obtained.

Further, the present invention according to claim 6 is characterized in that, in the random number generator according to any one of claims 1 to 5, a wide band amplifier is used as the amplifier. With this configuration, it is possible to generate stable random numbers at high speed by amplifying a noise component having a particularly high frequency among the noise components over a wide band and using the amplified noise component to generate a random pulse.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a random number generator of the present invention will be described below with reference to the drawings.

FIG. 1 shows the basic configuration of a random number generator 1 according to the first embodiment of the present invention, which comprises a noise generator circuit 2 having a noise source and an amplifier, a voltage comparator and a sawtooth wave generator. The pulse width modulation circuit 3, a random number generation circuit 6 including a latch circuit and a uniformization circuit, a timing generation circuit 4 and the like. The reference numeral 5 is, for example, 40 MHz
Is a high-speed internal clock.

In the random number generator 1 having the above-described structure, the white noise generated by the noise source is amplified by the amplifier and then compared with the sawtooth wave from the sawtooth wave generator in the voltage comparator of the pulse width modulation circuit 3 in the next stage. Pulses whose pulse width changes randomly according to the noise level (random pulse)
Is converted to. The latch circuit refers to the reference pulse signal at the changing edge portion of the random pulse, and serial 1 according to the state of "0" or "1" of the reference pulse signal.
The general operation is to continuously generate a random number of bits, and in the present embodiment, in order to further eliminate the bias in the appearance rate of the random numbers, the random numbers generated in the latch circuit that may cause the bias are equalized by the equalizing circuit. It is uniformized by.

2 to 5 show the circuit configuration of each block described above. FIG. 2 shows a noise generating circuit, FIG. 3 shows a pulse width modulating circuit, FIG. 4 shows a timing generating circuit, and FIG. 5 shows a random number generating circuit. The details of each circuit will be described below.

The electrical noise required to generate random numbers is shown in FIG.
Is generated by the noise generation circuit 2 of FIG. The noise generating circuit 2 is composed of a circuit element serving as a noise source, and a two-stage amplifier circuit including a low-noise wide-band pre-stage amplifier U1A, main amplifier U2A, feedback resistors R2 and R4, capacitors C2 and C3, and the like. . In this circuit, the main noise source is the resistor R1, but in reality, weak voltage and current fluctuations generated by all active circuit elements (passive elements, active elements) contribute as noise sources. . The white noise contains a noise component over a wide band from low frequency to high frequency. The amplifiers U1A and U2A are compatible with a wide frequency band in order to speed up the generation of random numbers, and a noise signal having a particularly high frequency among the noise components over a wide band is voltage-amplified and the noise signal N
The OISE is output to the pulse width modulation circuit 3 shown in FIG.
Note that Vref1 and Vref2 in FIG. 2 are offset voltages of the pre-stage amplifier U1A and the main amplifier U2A, and are set according to the amplitude of a sawtooth wave described later.

As shown in FIG. 3, the pulse width modulation circuit 3
Is composed of a sawtooth wave generator and a high-speed comparator U3A (voltage comparator).

The sawtooth wave generator includes transistors Q1 to Q1.
A current mirror circuit composed of Q3 and an input resistor R5 is provided, and the capacitor C4 is charged with a constant current from the power supply Vcc side through the transistors Q2 and Q3, so that one end of the capacitor C4 is maintained at a constant rate from the state of zero voltage. It causes an increasing voltage change. The rate of increase of this voltage, that is, the slope of the charging waveform is determined by the resistance value of the input resistor R5 and the electrostatic capacitance of the capacitor C4. A reset pulse PWM-R is generated at a predetermined timing when the charging voltage of the capacitor C4 rises to a predetermined level (5Vp-p in the present embodiment), turning on the transistor Q4 and turning on the charge charged in the capacitor C4 to the transistor Q4. It discharges to the GND side via. By this discharging operation, the charge waveform of the capacitor C4 returns to the state of zero voltage. After the reset is released, the charging / discharging operation of the capacitor C4 is repeated again in a predetermined cycle, and as shown in FIG.
A sawtooth wave RAMP synchronized with is generated. The reset pulse PWM-R flips the internal clock CLK_INT in the timing generation circuit 4 shown in FIG.
It is divided and output by the flops U1 and U2, the counter U3 and the like at a predetermined division ratio.

This sawtooth wave RAMP is input to the-input terminal of the comparator U3A via a resistor R6, and is generated in the noise generating circuit 2 to the + input terminal of the comparator U3A via a resistor R7. The noise signal NOISE is input. Then, the noise signal NOISE and the voltage of the sawtooth wave RAMP are compared by the comparator U3A, so that the output of the comparator U3A is inverted at the intersection of the sawtooth wave and the noise signal, as shown in FIG. Random pulse PWM_ that changes the width randomly according to
N is generated. The trailing edge (falling edge) of this random pulse PWM_N is always synchronized with the reset pulse PWM-R, and only the leading edge (rising edge) fluctuates according to the noise level.

As described above, in the present embodiment, the amplitude of the sawtooth wave RAMP is set to 5 Vp-p, so that the noise signal NOISE always exists somewhere within this amplitude, the temperature change and the power supply. Since the gains of the amplifiers U1A and U2A and the offset voltages Vref1 and Vref2 are set in consideration of the fluctuation of the noise level due to the fluctuation of the voltage, a stable pulse width modulation operation can always be obtained. Further, in the present embodiment, since the noise component having a particularly high frequency is used and this high frequency noise is configured to be oscillated within the cycle of the sawtooth wave and within the maximum amplitude of the sawtooth wave, the comparator U3A A fast and stable pulse can be obtained from the output of.

The random number generation circuit 6 shown in FIG. 5 includes a latch circuit using an edge trigger type flip-flop U4 such as a D flip-flop. The random pulse PWM_N from the comparator U3A is input to the clock terminal CLK of the D flip-flop U4, and the internal clock CLK_INT used as the reference pulse signal is input to the data terminal D, as shown in FIG. Further, by referring to the states of "0" and "1" of the internal clock CLK_INT at the trailing edge of the random pulse PWM_N, the output Q responds to the state of "0" or "1" of the internal clock CLK_INT. The serial random number Rg01 of "0" or "1" is continuously output at the cycle of the sawtooth wave (about 1 μsec).

Here, "0" and "1" of the random number Rg01 have no correlation between before and after, but the occurrence frequency of each may be biased due to the difference in the width of the internal clock and the temporal variation. (A state of "0" or a state of "1" may be continuously output). In the present embodiment, in order to eliminate such a bias in the appearance rate of random numbers, a homogenization circuit using the von Neumann method is provided. This homogenizing circuit is composed of a shift register U5 and a gate circuit U6, and uses the outputs Q ₀ and Q ₁ of the shift register U5 to create a pair of serial random numbers Rg01 which do not overlap in time, and the pair The random number is input to the gate circuit U6 and sequentially converted into a random number without bias. That is, as shown in Table 1, when the random number pair is "00" or "11", this random number is discarded, when the random number pair is "01", the random number is "1", and when it is "10" Is a random number “0”. Also, the reverse is also possible.

An effective random number (without regularity, correlation, or periodicity of appearance of random numbers) thus uniformized is D
The flip-flop U7 synchronizes with the clock CLK_10 and outputs the random number RNB together with the synchronization signal RNB_F. The synchronization signal RNB_F is a D flip
It is generated by the flop U8 and the shift register U9.

[0024]

[Table 1]

By the way, the serial random number RNB is often used after being converted into a parallel random number (for example, 8 bits). As a method of generating a parallel random number from a serial random number, (1) a method of performing serial / para conversion of a random number RNB using shift registers U10 and U11 as in the circuit configuration of FIG. 6, and (2) not shown, A method is known in which eight serial random number generators 1 are simply provided side by side, but both have drawbacks as described in (1) and (2) below. That is, in the method (1), it takes a long time to perform the serial / para conversion.
In order to increase the generation rate of random numbers, it is necessary to increase the slope of the sawtooth wave and raise the frequency, but it is difficult to shorten the cycle of the sawtooth wave in terms of a circuit. Although the method (2) is efficient, the number of analog circuits increases and the cost increases, and when there are a plurality of noise sources, they affect each other and have some phase, resulting in each Bit values may not be independent.

Therefore, in the first embodiment, one noise source is provided, and as many pulse width modulation circuits 3 as the number of bits are provided, and the resistance value of the input resistor R5 of the sawtooth wave generator and the static capacitance of the capacitor C4 are respectively provided. By changing the capacitance value, as shown in FIG.
A plurality of (eight types) sawtooth waves having constant frequencies having different slopes are generated as shown in (b). Note that FIG.
In order to change the direction of the sawtooth waveform as shown in (a) and (b), the power supplies Vcc and GN of the current mirror circuit described above are used.
It is sufficient to replace D with the configuration. As described above, by using a plurality of sawtooth waves each having a different slope, it is possible to equivalently reduce the reference timing with noise little by little, and as described above, without increasing the slope of the sawtooth wave (that is, It becomes possible to obtain a plurality of continuous random pulses with a slight time difference in a short time (without shortening the cycle of the sawtooth wave). As a result, random numbers can be efficiently generated with a simple circuit configuration and high speed can be realized.

9 to 11 show configuration examples of the parallel random number generator based on the above configuration. As described above, these are equipped with a single noise source and a plurality of sawtooth wave generators, and have different configurations in the method of equalization.

That is, FIG. 9 shows a configuration in which a pair of random numbers is formed for each latch circuit and is made uniform by the method of von Neumann, and FIG. 10 is a configuration in which a pair is formed between adjacent latch circuits. FIG. 11 shows a configuration in which a selection circuit is provided to automatically change the combination for forming a pair of latch circuits. All of them can generate random numbers efficiently with a simple circuit configuration.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 12 shows a basic configuration of the random number generator 1 according to the second embodiment of the present invention, which includes a noise generating circuit 2, a pulse width modulation circuit 3, and a random number generating circuit 6.
And the timing generation circuit 4 and the like. The configuration of the random number generator 1 is almost the same as that of the first embodiment, but the AGC is provided between the two-stage amplifiers in the noise generating circuit 2.
The difference is that a circuit (amplification factor control circuit) is mounted and that the pulse width modulation circuit 3 is composed of a monostable multivibrator. The circuit configuration of the part different from that of the first embodiment will be described below.

FIG. 13 shows the configuration of the noise generating circuit 2 according to this embodiment. The noise generating circuit 2 includes a resistor 1 (which actually contains noise from all circuit elements in an active state) as a noise source, a low noise wideband pre-stage amplifier U1A, a main amplifier U2A, and these two amplifiers U.
It is composed of an AGC circuit provided between 1A and U2A. This AGC circuit includes a transistor Q1, resistors R3 to R7, R
9, capacitors C3 to C6 and the like. The main amplifier U2A has two independent output terminals, one of which is connected to a monostable multivibrator, which will be described later, and the other output terminal of which is connected to resistors R5 and R9. In this configuration, the voltage generated in the resistor R9 is the resistance R5.
Is fed back to the gate side of the transistor Q1 via, and its average value is kept substantially constant. That is, since the drain-source voltage of the transistor Q1 changes depending on the gate potential, it plays a role equivalent to that of a variable resistor, and forms a voltage dividing circuit together with the resistor R3. This voltage dividing circuit applies the noise amplified by the pre-stage amplifier U1A to the main amplifier U2.
A DC voltage corresponding to the output of A is added and the main amplifier U2A
As a result, the average value of the output of the main amplifier U2A is kept substantially constant.

Since the white noise has temperature dependency and its fluctuations occur in various bands, the average value of the noise observed in a longer time than the internal clock cycle (a noise component having a low frequency can be regarded as a DC voltage). ) Varies. This variation in the DC voltage varies the width of the pulse generated in the monostable multivibrator described later, which adversely affects the subsequent random number generation. However, in the present embodiment, the AGC circuit described above is mounted, and the temperature etc. This problem is solved by automatically controlling the gain of the amplifier U2A and always keeping the average value of the output constant even if the average value of the noise voltage fluctuates.

The pulse width modulation circuit 3 shown in FIG.
A first monostable multivibrator (pulse generating means) including a feedback circuit including R gates U1B and U2B, resistors R1 and R2, and an RC charging circuit including a capacitor C2; a feedback circuit including NOR gates U3B and U4B and a resistor R3; R4, capacitor C3
Second monostable composed of RC charging circuit by
The multivibrator is provided, and the connection point between the resistors R1 and R2 of the first monostable multivibrator is connected to one output terminal of the main amplifier U2A via the capacitor C1.

These first and second monostable multivibrators are provided with a trigger signal TIME__ generated by the timing generation circuit 4 (the circuit structure is not shown).
1 to generate a pulse having a pulse width according to the time constant of each RC charging circuit, as shown in FIG. However, in the RC charging circuit of the first monostable multivibrator, the main amplifier U2A is connected via the capacitor C1.
Since the amplified noise voltage from is added, the potential at the connection point between the resistors R1 and R2 varies depending on the noise level, and the charging time for the capacitor C2 varies. In response to this, the pulse width of the output pulse RNP changes. That is, when the added noise level becomes high, the charging time to the capacitor C2 becomes short and the pulse width of the output pulse RNP becomes short, and when the noise level becomes low, the pulse width becomes long. The leading edge (rising edge) of this output pulse RNP is synchronized with the trigger signal TIME_1, and only the trailing edge (falling edge) changes according to the noise level.
On the other hand, the output pulse RNP_M of the second monostable multivibrator has a constant pulse width determined by the time constant of the RC charging circuit. The value of C3 is set. This output pulse PNP_M
Is used as a reference pulse signal when generating a random number.

These output pulses RNP and RNP_M are input to the random number generation circuit 6 in the next stage. Although the circuit configuration of the random number generation circuit 6 is almost the same as the configuration of the first embodiment shown in FIG. 5, it is not shown. However, in the case of the second embodiment, the clock terminal CLK of the D flip-flop U4 shown in FIG. The output pulse RNP_M is input to the data terminal D, and the output pulse RNP is input to the data terminal D. As shown in FIG. 15, a serial random number Rg01 is generated at the output Q by referring to the states of "0" and "1" of the output pulse RNP at the trailing edge (falling edge) of the output pulse RNP_M. This random number Rg01 is equalized by the equalizing circuit using the von Neumann method as in the first embodiment.

FIG. 16 shows the configuration of an 8-bit parallel random number generator according to the second embodiment. In this configuration,
In order to avoid mutual interference between the monostable multivibrator outputs, which is likely to occur when the same noise source is used for each, the time constants of the RC charging circuits of these eight sets of monostable multivibrator are different from each other. Pulses having different average widths are generated. This eliminates the correlation of 8 bit random numbers,
It is possible to efficiently generate effective random numbers with uniformity. However, the average values of the pulse widths of the pair of monostable multivibrators must be matched.

[0036]

As described above, according to the present invention,
The random pulse for random number generation is generated by comparing the noise signal with the sawtooth wave or by changing the time constant of the monostable multivibrator according to the noise. It is possible to efficiently generate random numbers and reduce costs. Further, by using a noise component having a particularly high frequency among the noise components over a wide band, it is possible to generate random numbers at high speed and stably.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic functional configuration of a random number generator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a noise generation circuit of the random number generator.

FIG. 3 is a diagram showing a pulse width modulation circuit of the random number generator.

FIG. 4 is a diagram showing a timing generation circuit of the random number generator.

FIG. 5 is a diagram showing a random number generation circuit of the random number generator.

FIG. 6 is a diagram showing a random-number serial-to-serial conversion circuit.

FIG. 7 is a diagram showing a waveform of each part of the random number generator.

FIG. 8 is a diagram showing sawtooth waveforms having different slopes.

FIG. 9 is a block diagram showing a configuration of a parallel random number generator according to the first embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a parallel random number generator different from that of FIG.

FIG. 11 is a block diagram showing a configuration of a parallel random number generator different from that of FIG.

FIG. 12 is a block diagram showing a basic functional configuration of a random number generator according to a second embodiment of the present invention.

FIG. 13 is a diagram showing a noise generation circuit of the random number generator.

FIG. 14 is a diagram showing a pulse width modulation circuit of the random number generator.

FIG. 15 is a diagram showing a waveform of each part of the random number generator.

FIG. 16 is a block diagram showing a configuration of a parallel random number generator according to a second embodiment of the present invention.

[Explanation of symbols]

1 random number generator 2 noise generation circuit 3 pulse width modulation circuit 5 Timing generation circuit 6 Random number generation circuit

Claims (6)

[Claims] 1. A random number generator for generating "0" or "1" of random number data by utilizing a random phenomenon of electrical noise such as white noise, comprising a noise source and an amplifier for amplifying noise. , A reference pulse signal, a pulse width modulation circuit that randomly changes the pulse width according to the noise level based on the reference pulse signal, and a state of "0" or "1" of the output pulse of the pulse width modulation circuit And a random number generator for generating random number data "0" or "1" by comparing the states of "0" and "1" of the reference pulse signal. 2. The pulse width modulation circuit comprises a sawtooth wave generator that generates a sawtooth wave, and a voltage comparator that compares the voltage of the sawtooth wave with a noise voltage. Random number generator described in. 3. A plurality of sawtooth wave generators that generate sawtooth waves each having a different slope are provided in parallel, and a plurality of random number data are continuously generated with a time difference due to the difference in the slopes of the sawtooth waves. The random number generator according to claim 2, wherein the random number generator is a random number generator. 4. The RC of the pulse width modulation circuit, wherein a charging time randomly changes according to a noise voltage.
The random number generator according to claim 1, wherein the random number generator has a charging circuit, and is configured by pulse generation means for generating a pulse having a pulse width according to a charging time of the RC charging circuit. 5. The pulse generating means includes a monostable
5. A multivibrator is used, wherein
Random number generator described in. 6. The random number generator according to claim 1, wherein a wide band amplifier is used as the amplifier.