A threshold-adjustable RO PUF device and output sequence method

Abstract

The present application relates to a kind of threshold adjustable RO PUF device and output sequence method, belong to information security technical field, solve the problem that the two key design indexes of existing RO PUF uniqueness and stability are difficult to compromise implementation.For threshold adjustment module, at least two ring oscillators and at least one counting comparison module;Wherein, every two ring oscillators is a group, and each group corresponds to a counting comparison module;Threshold adjustment module is used to set the threshold gear of the clock oscillation frequency difference generated by every two ring oscillators in each group;Wherein, threshold gear is adjustable;Counting comparison module is used to receive threshold gear and the clock oscillation frequency generated by two ring oscillators in corresponding group, obtains corresponding frequency difference threshold according to threshold gear, and the clock oscillation frequency difference generated by two ring oscillators is counted, obtains a bit output by comparing clock oscillation frequency difference with frequency difference threshold;The bit output corresponding to all groups is used as the output response data of RO PUF.

Description

Technical Field

[0001] This invention relates to the field of information security technology, and in particular to a threshold-adjustable RO PUF device and an output sequence method. Background Technology

[0002] Physically Unclonable Functions (PUFs), due to their inherent physical anti-cloning, uniqueness, and randomness, are known as "physical fingerprints" and have been considered a new fundamental technology for information security since their inception. In the development and application of PUFs, uniqueness and stability are key design metrics. Uniqueness refers to the difference between responses produced by different chips under the same stimulus conditions. Generally, chip output responses are represented by binary sequences; the closer the sequence difference is to 50%, the better the uniqueness. Stability refers to the difference between multiple responses produced by the same chip under the same stimulus conditions. Generally, chip output responses are represented by binary sequences; the closer the sequence difference is to 0%, the better the stability. However, designing PUFs based on existing general-purpose integrated circuit processes is quite challenging. One important reason is that general-purpose integrated circuit processes aim for good uniformity in the mass production of chips, while PUFs aim for uniqueness between each chip, and also require the output sequence produced by the same chip to be stable.

[0003] The Ring Oscillator (RO) PUF is a widely studied PUF technology implementation. A typical RO PUF design architecture consists of an array of n identical ROs, a counter, and a comparator. Theoretically, ROs of the same design should output the same oscillation frequency. However, in reality, due to manufacturing process errors, different ROs have different frequencies. Therefore, the RO array selects two ROs according to a certain strategy, records their frequencies using a counter, and obtains the single-bit response of the PUF output by comparing the magnitudes of these two frequencies. By selecting multiple pairs of ROs, a multi-bit PUF output sequence is obtained.

[0004] The uniqueness and stability of the output sequence of a RO PUF are related to factors such as the oscillation frequency, arrangement, and comparison strategy of its internal RO array, but most importantly, they are related to the magnitude of the output frequency difference between the compared ring oscillators within the RO PUF. Selecting ring oscillators with a large output frequency difference for comparison can improve the stability of the RO PUF output sequence; selecting ring oscillators with a small output frequency difference can improve the uniqueness of the RO PUF output sequence. Therefore, in the design of a RO PUF, a compromise must be made regarding the output frequency difference between the compared ring oscillators. However, the design, manufacturing, packaging, testing, and application of integrated circuit chips is a lengthy process. Due to its inherent sensitivity to differences, deviations in any production stage can lead to changes in the characteristics of the PUF output sequence.

[0005] Therefore, existing ROPUFs are susceptible to various factors during chip development due to their physical characteristics, making it difficult to achieve a compromise between the two key design metrics of uniqueness and stability. Summary of the Invention

[0006] Based on the above analysis, the embodiments of the present invention aim to provide a threshold-adjustable RO PUF device and output sequence method to solve the problem that it is difficult to achieve a compromise between the two key design indicators of uniqueness and stability in existing RO PUFs.

[0007] On one hand, embodiments of the present invention provide a threshold-adjustable RO PUF device, comprising: a threshold adjustment module, at least two ring oscillators and at least one counting comparison module; wherein, every two ring oscillators form a group, and each group corresponds to one counting comparison module;

[0008] The two ring oscillators in each group are used to generate clock oscillation frequencies according to the received excitation signal;

[0009] The threshold adjustment module is used to set a threshold level for the difference in clock oscillation frequencies generated by the two ring oscillators in each group; wherein the threshold level is adjustable.

[0010] The counting comparison module is used to receive the threshold level and the clock oscillation frequency generated by the two ring oscillators in the corresponding group, obtain the corresponding frequency difference threshold according to the threshold level, and count the clock oscillation frequency difference generated by the two ring oscillators in the corresponding group. By comparing the clock oscillation frequency difference with the frequency difference threshold, a bit output is obtained; the bit outputs corresponding to all groups are used as the output response data of RO PUF.

[0011] Furthermore, the difference in clock oscillation frequencies generated by the two ring oscillators is the difference in the number of rising or falling edges of the two clock oscillation frequencies.

[0012] Furthermore, the counting comparison module includes a first detection module, a second detection module, a counting module, an accumulation update module, and an adjustment comparison module;

[0013] The first detection module and the second detection module are respectively used to generate a first pulse and a second pulse according to the rising edge or falling edge of the received clock oscillation frequency, and output them to the counting module;

[0014] The adjustment module is used to obtain a corresponding frequency difference threshold based on the received threshold level, and output the frequency difference threshold to the counting module; wherein, the frequency difference threshold corresponds one-to-one with the threshold level;

[0015] The counting module is used to count based on the received first pulse and second pulse to obtain a count value, compare the count value with the received frequency difference threshold, and obtain a bit output.

[0016] Furthermore, the width of the first pulse and the second pulse generated by the first detection module and the second detection module is one clock cycle.

[0017] Further, the bit output is obtained in the counting module through the following steps:

[0018] When the first pulse generated by the first detection module is received, the count value is incremented by 1; when the second pulse generated by the second detection module is received, the count value is decremented by 1.

[0019] The updated count value is compared with the frequency difference threshold. If the count value is greater than or equal to the frequency difference threshold, 1 is output. If the count value is less than or equal to a negative frequency difference threshold, 0 is output.

[0020] Furthermore, the counting module is also provided with a comparison time; if the counting module does not output 0 or 1 within the comparison time, then no bit output is performed.

[0021] Furthermore, each ring oscillator is connected to an isolation module, which is used to isolate power supply ripple.

[0022] Furthermore, the isolation module includes an operational amplifier, a MOSFET, and resistors R1 and R2;

[0023] The operational amplifier has an inverting input terminal that receives a reference voltage; a non-inverting input terminal that is connected to one end of resistors R1 and R2; and an output terminal that is connected to the gate of a MOS transistor.

[0024] The source of the MOSFET is connected to the power supply; the drain is connected to the other end of resistor R1 and serves as the output voltage of the isolation module.

[0025] The other end of resistor R2 is grounded.

[0026] Furthermore, based on the output response data of the RO PUF device, the stability, uniqueness, and start-up time of the RO PUF are obtained, and the frequency difference threshold is adjusted according to the following criteria:

[0027] If the stability is less than the stability index in the technical specifications, the frequency difference threshold can be increased by adjusting the threshold level.

[0028] If the uniqueness is less than the uniqueness indicator in the technical indicators, then the frequency difference threshold is reduced by adjusting the threshold level.

[0029] If the startup time is greater than the startup time indicator in the technical specifications, the frequency difference threshold can be reduced by adjusting the threshold level.

[0030] On the other hand, embodiments of the present invention provide a method for outputting a RO PUF sequence, implemented using the aforementioned RO PUF device; the method includes the following steps:

[0031] Set the operating conditions and frequency difference threshold of the RO PUF;

[0032] An excitation signal is input to the RO PUF;

[0033] Read the RO PUF output response data;

[0034] The output response data is subjected to error correction processing to generate an output sequence.

[0035] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0036] This invention provides a threshold-adjustable RO PUF device and an output sequence method. By designing an adjustable frequency difference threshold, the frequency difference of the compared ring oscillator inside the RO PUF can be flexibly adjusted, which can avoid the influence of non-ideal factors introduced at various stages of the integrated circuit development process. Furthermore, the uniqueness and stability of the RO PUF can be flexibly adjusted according to the actual application environment or application requirements to meet the needs of actual information security applications.

[0037] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0038] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0039] Figure 1 A schematic diagram of the structure of the threshold-adjustable RO PUF device provided in an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the counting comparison module in the threshold-adjustable RO PUF device provided in an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the connection between the threshold-adjustable RO PUF device and the isolation module provided in an embodiment of the present invention;

[0042] Figure 4 This is a connection diagram of the isolation module provided in an embodiment of the present invention;

[0043] Figure 5 This is a flowchart illustrating the RO PUF output sequence method provided in an embodiment of the present invention. Detailed Implementation

[0044] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0045] Example 1

[0046] A specific embodiment of the present invention discloses a threshold-adjustable RO PUF device, such as... Figure 1 As shown, it includes: a threshold adjustment module, at least two ring oscillators and at least one counting comparison module; wherein, every two ring oscillators form a group, and each group corresponds to one counting comparison module;

[0047] The two ring oscillators in each group are used to generate clock oscillation frequencies according to the received excitation signal;

[0048] Specifically, the excitation signal is all the input signals, including pulse signals, reset signals, etc., generated by the circuit board or FPGA. Each ring oscillator has an identical design, its structure including a NAND gate and an even number of inverters; each inverter is connected end to end, including an output terminal and an input terminal, its output terminal is connected to one input terminal of the NAND gate, its input terminal is connected to the output terminal of the NAND gate, and the other input terminal of the NAND gate receives the excitation signal.

[0049] The threshold adjustment module is used to set a threshold level for the difference in clock oscillation frequencies generated by the two ring oscillators in each group; wherein the threshold level is adjustable.

[0050] Specifically, the threshold levels set in the threshold adjustment module correspond one-to-one with the frequency difference thresholds in the counting comparison module. When adjusting the frequency difference threshold, the level can be selected. The frequency difference threshold in the counting comparison module can be set to different frequency difference thresholds as needed. The higher the level, the higher the frequency difference threshold. For example, the threshold adjustment module has 4 threshold levels, each corresponding to a frequency difference threshold of 3, 5, 15, and 30 in the counting module, respectively.

[0051] The counting comparison module is used to receive the threshold level and the clock oscillation frequency generated by the two ring oscillators in the corresponding group, obtain the corresponding frequency difference threshold according to the threshold level, and count the clock oscillation frequency difference generated by the two ring oscillators in the corresponding group. By comparing the clock oscillation frequency difference with the frequency difference threshold, a bit output is obtained; the bit outputs corresponding to all groups are used as the output response data of RO PUF.

[0052] Specifically, each group of ring oscillators in the RO array corresponds one-to-one with the bit position of the output response data. After each group of ring oscillators outputs bit data, the corresponding bit output is placed in the corresponding position to obtain the output response data of the RO PUF. The output response data can be output serially or in parallel according to the chip requirements. The correspondence between each group of ring oscillators in the RO array and the bit position of the output response data can be set according to actual needs.

[0053] It should be noted that the RO PUF device is equipped with a threshold adjustment module for setting the threshold level. Each group of ring oscillators is set to the same threshold level. By adjusting the threshold level, the threshold in the corresponding counting comparison module of all groups can be adjusted simultaneously.

[0054] Understandably, the RO PUF device contains several ring oscillators forming an RO array. Each pair of ring oscillators forms a group, and each group outputs one bit of data as one bit of the output response. The bit data output by all groups in the RO array constitutes the output response data of the RO PUF.

[0055] Compared with the prior art, the RO PUF device with adjustable threshold provided in this embodiment, by designing an adjustable frequency difference threshold, allows the frequency difference of the compared ring oscillator inside the RO PUF to be flexibly adjusted, which can avoid the influence of non-ideal factors introduced in various stages of the integrated circuit development process; it can also flexibly adjust the two key design indicators of uniqueness and stability of the RO PUF according to the actual application environment or application requirements, so as to meet the needs of actual information security applications.

[0056] In practice, the difference in clock oscillation frequencies generated by the two ring oscillators is the difference in the number of rising or falling edges of the two clock oscillation frequencies.

[0057] Understandably, due to the influence of manufacturing processes, individual ROs in an RO array with identical design parameters will have slight differences in their actual output oscillation frequencies. This is the source of the physical characteristics of the RO PUF. The difference in the output oscillation frequencies of each RO is determined by counting and comparing the number of rising (or falling) edges of each RO within a certain period of time, thus judging the speed of its frequency and obtaining the output random sequence, which is the RO PUF output response data.

[0058] When implementing, such as Figure 2 As shown, the counting comparison module includes a first detection module, a second detection module, a counting module, and an adjustment module;

[0059] The first detection module and the second detection module are respectively used to generate a first pulse and a second pulse according to the rising edge or falling edge of the received clock oscillation frequency, and output them to the counting module;

[0060] The adjustment module is used to obtain a corresponding frequency difference threshold based on the received threshold level, and output the frequency difference threshold to the counting module; wherein, the frequency difference threshold corresponds one-to-one with the threshold level;

[0061] The counting module is used to count based on the received first pulse and second pulse to obtain a count value, compare the count value with the received frequency difference threshold, and obtain a bit output.

[0062] In specific implementation, the width of the first pulse and the second pulse generated by the first detection module and the second detection module is one clock cycle.

[0063] In specific implementation, the bit output is obtained in the counting module through the following steps:

[0064] When the first pulse generated by the first detection module is received, the count value is incremented by 1; when the second pulse generated by the second detection module is received, the count value is decremented by 1.

[0065] The updated count value is compared with the frequency difference threshold. If the count value is greater than or equal to the frequency difference threshold, 1 is output. If the count value is less than or equal to a negative frequency difference threshold, 0 is output.

[0066] Understandably, the counting and comparison module determines the frequency speed by the number of rising (or falling) edges of the two compared ROs, and outputs a random sequence. By setting a frequency difference threshold, the basis for determining the frequency speed is adjusted. In other words, when comparing the clock oscillation frequencies of the two ring oscillators, if the frequency difference is greater than the frequency difference threshold, it is determined that one clock oscillation frequency is faster than the other. If the frequency difference is less than the negative frequency difference threshold, it is determined that one clock oscillation frequency is slower than the other.

[0067] Preferably, the counting module is further provided with a comparison time; if the counting module does not output 0 or 1 within the comparison time, then no bit output is performed.

[0068] Specifically, the comparison time can be set according to the time interval for the RO PUF device to extract the output response. If no bit has been output when extracting the output response, extraction is not performed, and the missing positions in the output response can be filled by random filling.

[0069] It should be noted that the uniqueness and stability of the RO PUF's output sequence are related to the voltage fluctuations of its power supply. Voltage fluctuations will affect the oscillation frequency of the ring oscillator in the RO PUF, thus affecting its stability and uniqueness. Even when using the best voltage source device, the output voltage will still have ripple. Furthermore, the voltage is highly susceptible to environmental factors during transmission, such as transmission line and circuit board noise, which will inevitably cause voltage fluctuations and affect the stability of the RO PUF. Therefore, the RO PUF device provided in this embodiment also includes the following settings:

[0070] When implementing, such as Figure 3 As shown, each ring oscillator is connected to the power supply via an isolation module, which is used to isolate power supply ripple. It can be understood that by adjusting the internal circuit logic, device types, and device parameters of the isolation module, the impact of power supply ripple on PUF stability can be effectively resisted while ensuring the voltage required for normal operation of the RO array circuit.

[0071] In specific implementation, such as Figure 4 As shown, the isolation module includes an operational amplifier AMP, a MOSFET M1, and resistors R1 and R2; wherein, the MOSFET M1 has driving capability and can drive the connected RO array;

[0072] The operational amplifier AMP receives a reference voltage at its inverting input; its non-inverting input is connected to one end of resistors R1 and R2; and its output is connected to the gate of a MOSFET. The reference voltage Vin is set according to the voltage requirements of the connected RO array.

[0073] The source of the MOS transistor M1 is connected to the power supply; the drain is connected to the other end of the resistor R1 and serves as the output voltage of the isolation module.

[0074] The other end of resistor R2 is grounded.

[0075] Preferably, resistors R1 and R2 can be set as adjustable resistors, which can adjust the output voltage according to the power supply voltage requirements of the connected RO array to ensure the voltage required for the normal operation of the RO array circuit.

[0076] Understandably, the reference voltage and the feedback voltage obtained by voltage division through resistors R1 and R2 serve as the two inputs of the operational amplifier AMP. The output of the operational amplifier controls the gate of MOSFET M1, causing MOSFET M1 to operate in the linear region. MOSFET M1 in the linear region can be equated to a voltage-controlled variable resistor, working together with resistors R1 and R2 to participate in voltage division, thereby generating the output voltage Vout. Since the connected power supply voltage or load current may fluctuate, this will cause changes in the output voltage Vout. At this time, under the combined action of MOSFET M1 and resistors R1 and R2, the gate voltage of MOSFET M1 can be dynamically adjusted, that is, the magnitude of the conduction current of MOSFET M1 can be dynamically controlled, thereby stabilizing the output voltage.

[0077] The specific working process of the isolation module is as follows:

[0078] When the output voltage decreases, the feedback voltage under the voltage division effect of resistors R1 and R2 also decreases accordingly, causing the output voltage of the operational amplifier AMP to decrease accordingly, that is, the gate voltage of MOSFET M1 decreases. At this time, the voltage difference between the gate and source of MOSFET M1 increases, the drain current increases, and the output voltage Vout increases accordingly, thereby suppressing the decrease in output voltage and keeping the output voltage Vout stable.

[0079] When the output voltage increases, the feedback voltage under the voltage division effect of resistors R1 and R2 also increases accordingly, which makes the output voltage of the operational amplifier AMP increase accordingly, that is, the gate voltage of MOS transistor M1 increases. At this time, the voltage difference between the gate and source of MOS transistor M1 decreases, the drain current decreases, and the output voltage Vout decreases accordingly, thereby suppressing the increase of the output voltage and keeping the output voltage Vout stable.

[0080] During implementation, stability, uniqueness, and start-up time are obtained based on the output response data of the RO PUF device, and the frequency difference threshold is adjusted according to the following criteria:

[0081] If the stability is less than the stability index in the technical specifications, the frequency difference threshold can be increased by adjusting the threshold level.

[0082] If the uniqueness is less than the uniqueness indicator in the technical indicators, then the frequency difference threshold is reduced by adjusting the threshold level.

[0083] If the startup time is greater than the startup time indicator in the technical specifications, the frequency difference threshold can be reduced by adjusting the threshold level.

[0084] It should be noted that the RO (Reverse Oscillator) contains noise, which accumulates over time. This noise increases with the duration of the RO output waveform, causing differences between two identical RO output waveforms in the RO PUF (Power-On-Flight) output, ultimately resulting in a 1-bit PUF value. A smaller frequency difference threshold means fewer RO output waveform cycles are needed to determine the 1-bit PUF value. This makes the output highly susceptible to noise, leading to instability and ultimately reducing the overall stability of the RO PUF output sequence, while increasing its uniqueness. Conversely, a larger frequency difference threshold means more RO output waveform cycles are needed to determine the 1-bit PUF value. This eliminates uncertainties introduced by noise and interference, improving the stability of the output and thus the overall stability of the RO PUF output sequence. Furthermore, the magnitude of the frequency difference threshold actually represents the number of waveform cycles that are pulled apart (differentiated) by the set frequency difference threshold for each pair of compared RO output waveforms in the RO PUF. Therefore, the larger the frequency difference threshold, the longer the time it takes for the RO PUF chip to start working and finally output the bit sequence, i.e., the startup time.

[0085] Specifically, stability is obtained from the output response data of the RO PUF device in the following manner:

[0086] The response data of the same RO PUF under different environments and the response data under ideal environment were obtained under the same excitation. The environmental factors include temperature and operating voltage. The ideal environment and different environments are set according to the actual scenario.

[0087] The intra-chip Hamming distance μ is calculated based on the response data output under different environments and the response data output under ideal environments. intra ;

[0088] Based on the obtained intra-film Hamming distance μ intra The stability β is obtained. stability =1-μ intra .

[0089] More specifically, if β stability <β standardIf the frequency difference threshold is increased by adjusting the threshold setting, the stability of the RO PUF can be improved. When increasing the frequency difference threshold, it can be increased sequentially according to the setting, and the stability test can be repeated until the stability meets the stability index requirements. Wherein, β... standard The stability metrics set for the actual application scenarios of this RO PUF.

[0090] Specifically, uniqueness is obtained from the output response data of the RO PUF device in the following way:

[0091] The response data of multiple devices with the same RO PUF structure were obtained under the same excitation.

[0092] The inter-chip Hamming distance μ is calculated based on the response data output from multiple devices. middle ;

[0093] Based on the obtained inter-piece Hamming distance μ middle The uniqueness α is obtained. stability =μ middle .

[0094] More specifically, if α stability <α standard If the frequency difference threshold is reduced by adjusting the threshold setting, the uniqueness of the RO PUF can be improved. When reducing the frequency difference threshold, it can be decreased sequentially according to the setting, and the uniqueness test can be repeated until the uniqueness meets the requirements. Wherein, α standard This is a unique metric set for the actual application scenario of the RO PUF. Similarly, the startup time can be measured. If the startup time is greater than the startup time target in the technical specifications, the startup time of the RO PUF can be shortened by adjusting the threshold level to reduce the frequency difference threshold. When reducing the frequency difference threshold, the frequency difference threshold can be reduced sequentially according to the level setting, and the startup time can be repeatedly tested until the startup time meets the startup time target requirements.

[0095] It is understood that the threshold-adjustable RO PUF device proposed in this embodiment can be configured according to actual needs at different stages such as the design and development of RO PUF and field use, thereby improving the RO PUF output sequence input characteristics. This is of great significance and value for the actual promotion and application of RO PUF chips.

[0096] Example 2

[0097] A specific embodiment of the present invention discloses a method for outputting a ROPUF sequence, implemented using the aforementioned ROPUF device; as follows: Figure 5 As shown, the method includes the following steps:

[0098] Set the operating conditions and frequency difference threshold of the RO PUF; wherein, the operating conditions include the sampling clock frequency;

[0099] An excitation signal is input to the RO PUF;

[0100] Read the RO PUF output response data;

[0101] The output response data is subjected to error correction processing to generate an output sequence.

[0102] It should be noted that since the output sequence method in this embodiment can be referenced from the aforementioned RO PUF device, this is a repetition and will not be repeated here. Because this method embodiment shares the same principle as the aforementioned device embodiment, it also possesses the corresponding technical effects of the aforementioned device embodiment.

[0103] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0104] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A threshold-adjustable RO PUF device, characterized in that, include: The system includes a threshold adjustment module, at least two ring oscillators, and at least one counting comparison module; wherein each pair of ring oscillators forms a group, and each group corresponds to one counting comparison module. The two ring oscillators in each group are used to generate clock oscillation frequencies according to the received excitation signal; The threshold adjustment module is used to set a threshold level for the difference in clock oscillation frequencies generated by the two ring oscillators in each group; wherein the threshold level is adjustable. The counting comparison module is used to receive the threshold level and the clock oscillation frequency generated by the two ring oscillators in the corresponding group, obtain the corresponding frequency difference threshold according to the threshold level, and count the clock oscillation frequency difference generated by the two ring oscillators in the corresponding group. By comparing the clock oscillation frequency difference with the frequency difference threshold, a bit output is obtained; the bit outputs corresponding to all groups are used as the output response data of RO PUF. The counting comparison module includes a first detection module, a second detection module, a counting module, an accumulation update module, and an adjustment comparison module; The first detection module and the second detection module are respectively used to generate a first pulse and a second pulse according to the rising edge or falling edge of the received clock oscillation frequency, and output them to the counting module; The adjustment module is used to obtain the corresponding frequency difference threshold according to the received threshold level, and output the frequency difference threshold to the counting module; wherein, the frequency difference threshold corresponds one-to-one with the threshold level, and the higher the threshold level, the higher the frequency difference threshold. The counting module is used to count based on the received first pulse and second pulse to obtain a count value, and compare the count value with the received frequency difference threshold to obtain a bit output; Furthermore, based on the output response data of the RO PUF device, the stability, uniqueness, and start-up time of the RO PUF are obtained, and the frequency difference threshold is adjusted according to the following criteria: If the stability is less than the stability index in the technical specifications, the frequency difference threshold can be increased by adjusting the threshold level. If the uniqueness is less than the uniqueness indicator in the technical indicators, then the frequency difference threshold is reduced by adjusting the threshold level. If the startup time is greater than the startup time indicator in the technical specifications, the frequency difference threshold can be reduced by adjusting the threshold level.

2. The threshold-adjustable RO PUF device according to claim 1, characterized in that, The difference in clock oscillation frequencies generated by the two ring oscillators is the difference in the number of rising or falling edges of the two clock oscillation frequencies.

3. The threshold-adjustable RO PUF device according to claim 1, characterized in that, The width of the first pulse and the second pulse generated by the first detection module and the second detection module is one clock cycle.

4. The threshold-adjustable RO PUF device according to claim 3, characterized in that, The bit output is obtained in the counting module through the following steps: When the first pulse generated by the first detection module is received, the count value is incremented by 1; when the second pulse generated by the second detection module is received, the count value is decremented by 1. The updated count value is compared with the frequency difference threshold. If the count value is greater than or equal to the frequency difference threshold, 1 is output. If the count value is less than or equal to a negative frequency difference threshold, 0 is output.

5. The threshold-adjustable RO PUF device according to claim 4, characterized in that, The counting module is also provided with a comparison time; if the counting module does not output 0 or 1 within the comparison time, no bit output is performed.

6. The threshold-adjustable RO PUF device according to claim 1, characterized in that, Each ring oscillator is connected to an isolation module, which is used to isolate power supply ripple.

7. The threshold-adjustable RO PUF device according to claim 6, characterized in that, The isolation module includes an operational amplifier, a MOSFET, and resistors R1 and R2; The operational amplifier has an inverting input terminal that receives a reference voltage; a non-inverting input terminal that is connected to one end of resistors R1 and R2; and an output terminal that is connected to the gate of a MOS transistor. The source of the MOSFET is connected to the power supply; the drain is connected to the other end of resistor R1 and serves as the output voltage of the isolation module. The other end of resistor R2 is grounded.

8. A method for outputting the sequence of a RO PUF, characterized in that, The method is implemented using the RO PUF device according to any one of claims 1-7; the method includes the following steps: Set the operating conditions and frequency difference threshold of the RO PUF; An excitation signal is input to the RO PUF; Read the RO PUF output response data; The output response data is subjected to error correction processing to generate an output sequence.

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