Random number seed generator based on thermal noise

Abstract

The invention provides a random number seed generator based on thermal noise, and belongs to the field of cryptography. The method comprises the following steps of: 1, filtering high-frequency power supply ripples by using magnetic beads, and taking a bridge consisting of four precision resistors as a signal generator circuit; step 2, filtering direct current bias voltage of the bridge output through a capacitor; 3, constructing an instrument amplifier with the gain of 1000; 4, the output of the instrument amplifier is connected to a multi-stage differential amplifier to amplify the output signal of the instrument amplifier by 100-1000 times; 5, enabling the amplified signal to pass through an analog wave selection filter; and 6, inputting an output signal of the filter into an encryption system through an ADC circuit to serve as a random number seed of a random number generation algorithm.

Description

Technical Field

[0001] The invention belongs to the field of cryptography, and in particular relates to a random number seed generator based on thermal noise. Background Art

[0002] A random number seed generator based on thermal noise is an analog signal generation system that uses thermal noise as a signal source. Since thermal noise is a random phenomenon in nature, the system outputs true random numbers.

[0003] Random numbers are widely used in today's encryption systems. However, since random numbers are difficult to obtain, pseudo-random numbers are used as random number seeds, and then a series of random numbers are obtained through algorithms for use in encryption systems. The use of pseudo-random numbers may allow attackers to reverse the rules of random number generation and then attack existing systems, posing a great threat to security.

[0004] Traditional pseudo-random number generation schemes cannot fully meet security requirements, so it is necessary to find a cheap way to obtain true random numbers. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a random number seed generator based on thermal noise, the system obtains a thermal noise signal superimposed with common mode noise through a resistor bridge, and the signal is amplified and filtered at a later stage to obtain a true random number.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The design of the random number seed generator system based on thermal noise includes the following steps:

[0008] Step 1: Use magnetic beads to filter out high-frequency power supply ripple, and use a bridge composed of four precision resistors as a signal generator circuit;

[0009] Step 2: The DC bias voltage of the bridge output is filtered out by a capacitor;

[0010] Step 3: Construct an instrument amplifier with a gain of 1000. The positive input capacitor of the instrument amplifier is connected to bridge arm A, and the negative input capacitor is connected to bridge arm B.

[0011] Step 4: The output of the instrumentation amplifier is connected to a multi-stage differential amplifier circuit to amplify the output signal of the instrumentation amplifier by 100 to 1000 times, from nV level to V level;

[0012] Step 5: Pass the amplified signal through an analog wave selection filter. The wave selection filter is composed of a high-pass filter and a low-pass filter with very close cutoff frequencies. After the signal passes through the wave selection filter, a single frequency signal with an amplitude that changes with time is output;

[0013] Step 6: The output signal of the filter is input into the encryption system via the ADC circuit as a random number seed for the random number generation algorithm;

[0014] Assuming the input voltage is V, is the bridge resistance, is the current of each bridge arm. Therefore, the input and output of the bridge can be expressed as:

[0015] ;

[0016] ;

[0017] ;

[0018] in: is the power supply ripple, is the bridge node output voltage.

[0019] Due to production problems, the resistors cannot maintain consistency, and the current flowing through the resistors generates noise. Due to the influence of power supply ripple, in dynamic conditions, the instantaneous output voltage is:

[0020]

[0021]

[0022] in is the resistance error, Bridge arm voltage, is the noise generated by the corresponding resistor

[0023] After removing the DC bias, the signal enters the instrument amplifier with a gain of K and outputs for:

[0024]

[0025] because approaches 0, so:

[0026]

[0027] Where: K is the instrumentation amplifier gain, is the bridge noise difference.

[0028] Random number seed generator based on thermal noise. The input and output relationship of the differential amplifier is expressed as:

[0029]

[0030] in: is the voltage at the non-inverting input terminal, is the inverting input voltage, is the differential amplifier output voltage, R1 is the feedback loop resistor, and R2 is the connection resistor.

[0031] Random number seed generator based on thermal noise. The gate filter is expressed in the s domain as:

[0032]

[0033] Where s is the complex frequency domain differential operator, is the center frequency (center of the passband), is the cutoff frequency (the transition frequency from the passband to the stopband), and Q is the quality factor, which is related to the bandwidth of the filter.

[0034] Use the MFB circuit to implement the transfer function. In the second-order MFB bandpass filter framework, let C1=C2=C and the gain Kp:

[0035]

[0036]

[0037]

[0038] The ADC is used to sample the output of the wave selector, wherein the sampled amplitude is used as a random number seed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0040] Figure 1 A resistance bridge.

[0041] Figure 2 It is an instrumentation amplifier and a differential amplifier.

[0042] Figure 3 It is a pass filter circuit.

[0043] Figure 4 It is the work flow chart of the present invention. DETAILED DESCRIPTION

[0044] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0045] The accompanying drawings are only for illustrative purposes and are schematic diagrams rather than physical drawings. They cannot be construed as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the size of the actual product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the accompanying drawings. The same or similar reference numerals in the accompanying drawings of the embodiments of the present invention correspond to the same or similar parts.

[0046] The present invention provides a random number seed generator based on thermal noise, which obtains high-quality random numbers at low cost, filters out common-mode interference as an optimization goal, realizes random number seed generation through a bridge, an instrumentation amplifier, a differential amplifier, and a gate filter, and generates true random numbers, including the following steps:

[0047] Step 1: Use magnetic beads to filter out high-frequency power supply ripple, and use a bridge composed of four precision resistors as a signal generator circuit;

[0048] Step 2: The DC bias voltage of the bridge output is filtered out by a capacitor;

[0049] Step 3: Construct an instrument amplifier with a gain of 1000. The positive input capacitor of the instrument amplifier is connected to bridge arm A, and the negative input capacitor is connected to bridge arm B.

[0050] Step 4: The output of the instrumentation amplifier is connected to a multi-stage differential amplifier circuit to amplify the output signal of the instrumentation amplifier by 100 to 1000 times, from nV level to V level;

[0051] Step 5: Pass the amplified signal through an analog wave selection filter. The wave selection filter is composed of a high-pass filter and a low-pass filter with very close cutoff frequencies. After the signal passes through the wave selection filter, a single frequency signal with an amplitude that changes with time is output;

[0052] Step 6: The output signal of the filter is input into the encryption system via the ADC circuit as a random number seed for the random number generation algorithm;

[0053] Furthermore, the four bridge arms of the resistance bridge use precision resistors of the same size and with an accuracy of 0.02%.

[0054] Magnetic beads are added to the power input end of the bridge arm to filter out high-frequency noise. The bridge arm sampling point to the coupling capacitor to the instrument amplifier loop uses equal-length connections and is protected by ground vias. The loop area is as small as possible.

[0055] Use decoupling capacitors at the input and output of the instrumentation amplifier and connect them for a gain greater than 500.

[0056] The non-inverting terminal of the differential amplifier is grounded, the two stages are cascaded and the amplifier gain is set to 10, and RC filters are used at the input and output of each amplifier to filter out high-frequency interference.

[0057] A gating filter is used to accurately select the thermal noise of a single frequency band in the range greater than 1 / f and less than 1K. The noise amplitude is the true random number seed.

[0058] The ADC system uses 100F, which is 100 times the specific frequency F, as the sampling rate to convert the analog signal into a digital signal.

[0059] Furthermore, after the digital signal is input into the encryption system, the system allocates and calls to generate a random number sequence.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A random number seed generator based on thermal noise, characterized in that: The following steps are involved: Step 1: Use magnetic beads to filter out high-frequency power supply ripple, and use a bridge composed of four precision resistors as a signal generator circuit; Step 2: The DC bias voltage of the bridge output is filtered out by a capacitor; Step 3: Construct an instrument amplifier with a gain of 1000. The positive input capacitor of the instrument amplifier is connected to bridge arm A, and the negative input capacitor is connected to bridge arm B. Step 4: The output of the instrumentation amplifier is connected to a multi-stage differential amplifier circuit to amplify the output signal of the instrumentation amplifier by 100 to 1000 times, from nV level to V level; Step 5: Pass the amplified signal through an analog wave selection filter. The wave selection filter is composed of a high-pass filter and a low-pass filter with very close cutoff frequencies. After the signal passes through the wave selection filter, a single frequency signal with an amplitude that changes with time is output; Step 6: The output signal of the filter is input into the encryption system via the ADC circuit as a random number seed for the random number generation algorithm.

2. The random number seed generator based on thermal noise according to claim 1, characterized in that: Bridge; Assuming the input voltage is V, is the bridge resistance, is the current of each bridge arm; therefore, the bridge input and output can be expressed as ； ； ； in: is the power supply ripple, is the bridge node output voltage; Due to production problems, the resistors cannot maintain consistency, and the current flowing through the resistors generates noise. Due to the influence of power supply ripple, in dynamic conditions, the instantaneous output voltage is: ； ； in is the resistance error, Bridge arm voltage, is the noise generated by the corresponding resistor.

3. The random number seed generator based on thermal noise according to claim 1, characterized in that: After removing the DC bias, the signal enters the instrument amplifier with a gain of K and outputs for: ； because approaches 0, so: ； Where: K is the instrumentation amplifier gain, is the bridge noise difference.

4. The random number seed generator based on thermal noise according to claim 1, characterized in that: The amplifier circuit; wherein the input-output relationship of the differential amplifier is expressed as: ； in: is the voltage at the non-inverting input terminal, is the inverting input voltage, is the differential amplifier output voltage, R1 is the feedback loop resistor, and R2 is the connection resistor.

5. The random number seed generator based on thermal noise according to claim 1, characterized in that: The filter circuit transfer function; wherein the gate filter is expressed in the s domain as: ； Where s is the complex frequency domain differential operator, is the center frequency (center of the passband), is the cutoff frequency (the transition frequency from the passband to the stopband), and Q is the quality factor, which is related to the bandwidth of the filter.

6. The random number seed generator based on thermal noise according to claim 1, characterized in that: The filter transfer function circuit is implemented; the transfer function is implemented using the MFB circuit; in the second-order MFB bandpass filter framework, C1=C2=C and the gain Kp are: ； ； ； Cascading the circuits yields a fourth-order wave selector.

7. The random number seed generator based on thermal noise according to claim 1, characterized in that: The output signal is sampled; the selector output is sampled using an ADC, wherein the sampled amplitude is used as a random number seed.

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