Optical PUF chip, reading system and coding capacity evaluation method

Abstract

The invention provides an optical PUF (Physical Unclonable Function) chip based on a plasmon random structure, a reading system and a coding capacity evaluation method, the optical PUF chip comprises a substrate, a plurality of nano structures which are densely arranged and are obtained by adopting a porous nano film as a deposition auxiliary template for evaporation on the substrate, on the basis of randomness and local defects of a template and different gradients of angle deposition, the nanostructure has random differences in size, size and distribution, and shows different plasmon resonance effects; the nanostructure comprises a dense particle structure with statistical differences determined by the template aperture and a cluster island structure determined by random defects in the template. According to the invention, the speed of mass production of the plasmon chip can be obviously accelerated, the plasmon chip can be integrated with equipment such as a personal smart phone for use, additional equipment is not needed, the coding capacity, the safety and the stability can be improved in a simple and direct mode, and the requirements of different fields on the tag coding capacity and information verification can be met.

Description

Technical Field

[0001] The present invention relates to the fields of hardware security, product anti-counterfeiting and identity authentication technology, as well as optical chips and micro-nano manufacturing technology, and in particular to an optical PUF chip based on a plasmon random structure, a reading system and a coding capacity evaluation method. Background Art

[0002] As a digital fingerprint, "Physical Unclonable Function" (PUF) is essentially unaffected by reverse engineering and has the highest level of security. In practical applications, PUF is often presented as a physical object with inherent and unique characteristics in the form of a chip, in which information can be generated through a specific random and non-deterministic process, so it is unclonable and resistant to physical attacks. Currently, all commercial PUF chips are silicon-based integrated circuit PUF architectures, including memory PUFs such as SRAM and DRAM, and analog circuit PUFs. Their common characteristics are that they are based on mature integrated circuit process solutions and use the physical random fluctuations of the hardware system to achieve identity identification functions. Electrical PUF technology based on integrated circuits has been perfected in the past 20 years of development. However, at the same time, its corresponding attack technology has also been developed, and the game with PUF defense has become increasingly fierce. During this process, electrical PUF further exposed obvious shortcomings: first, there is a certain inherent bias in the deviation of integrated circuit process, which leads to insufficient randomness of PUF output; second, once the electrical PUF is prepared, it is difficult to reconstruct. After an exhaustive attack, the hardware protected by PUF may still face hardware security threats; finally, changes in the environmental conditions of the chip (such as temperature, environmental noise and electromagnetic interference) can easily cause changes in RAM random values, resulting in insufficient stability.

[0003] Optical PUF has incomparable advantages over electrical PUF, such as being less vulnerable to modeling attacks, having less entropy source restrictions, and being difficult to age and degrade, thus having higher security and practicality. The first optical PUF was proposed by a team at the Massachusetts Institute of Technology in 2002, based on the laser speckle generated by scattering of non-uniform optical media as a source of optical information. Subsequently, the materials and structures for developing chip-level optical PUFs have become increasingly diverse. In addition to graphic PUFs that only utilize the structural randomness and disorder that affect elastic scattering, there are also optical multimodal PUFs that utilize various light-matter interaction processes, such as luminescence processes, Raman scattering processes, and nonlinear processes. Materials are also not limited to conventional semiconductors, but have expanded to micron- and nanometer-scale photoluminescent materials, such as fluorescent proteins, quantum dots, perovskites, photoluminescent defect centers in diamonds, organic semiconductors, and so on.

[0004] The major problems that currently hinder many optical PUF technologies from moving from the laboratory to practical applications are as follows: 1) Optical PUFs based on complex luminescence and nonlinear processes usually require high-precision equipment such as pump sources, narrow linewidth lasers, and spectrometers to read PUF tags, which has high application costs and is not conducive to miniaturized integration and packaging. In the prior art, taking patent CN 116002689 B as an example, the proposed silicon-based optical PUF scheme uses 7 different optical response signals of nanomaterials (blank background, surface morphology, luminescence intensity of silicon nanomaterials, luminescence intensity of erbium ions, central luminescence wavelength of silicon nanomaterials, luminescence lifetime of silicon nanomaterials, and luminescence intensity ratio of silicon nanomaterials and erbium ions). The need for accurate measurement of luminescence wavelength and lifetime increases the complexity of the reading process to a certain extent. At the same time, this scheme requires strict control of the parameters of rare earth element doping, such as etching components, etching component ratio, added volume, etching time, temperature, cleaning, etc.; 2) The optical action process involved in the PUF work is not stable over a long period of time or in extreme environments, and phenomena such as luminescence may decrease, which greatly limits the working life of the PUF.

[0005] In addition, for high-capacity random key generation applications, existing optical PUFs that achieve ultra-large "Challenge-response pair" (CRP) capacity are often based on complex coding schemes, involving information control processes such as light field spatial domain, time domain, and frequency domain. Taking patent CN 107257285 B as an example, in order to improve the static coding capability, the patent proposes an authentication system based on single-photon excitation and optical PUF, but the static coding capability in the system is overly dependent on the regulation of laser speckle by digital micromirrors (DMD), which is not caused by the inherent device structure of the optical PUF. Over-reliance on DMD introduces a variety of limitations and disadvantages, including increased complexity, high costs caused by DMD integration, calibration errors, etc. DMD-related issues may lead to a decline in the performance of optical PUFs and limited scalability of coding capacity. Once this external component is omitted in the system, the static coding capability of the optical PUF is often the same as that of the electrical PUF, with the problem of limited CRP capacity.

[0006] To this end, the present invention proposes an optical PUF chip, coding system and coding capacity evaluation method based on plasmon random structure, which mainly aims to achieve significant improvements in three aspects:

[0007] 1) The processing and realization of "low-cost, large-scale, integrated" optical PUF chips can significantly speed up the chip production; 2) Compact and portable random information query system. Propose an efficient and convenient tag encoding and tag reading method that can be integrated with personal smartphones and portable devices without the need for additional equipment; 3) A low-cost multi-dimensional information expansion solution for multiple purposes and scenarios to improve coding capacity and security in a simple and direct way. Aims to meet the needs of different fields for tag coding capacity and information verification. Summary of the invention

[0008] The main purpose of the present invention is to provide an optical PUF chip, a reading system and a coding capacity evaluation method based on a plasmon random structure, aiming to realize an array-type integrated optical PUF architecture on a transparent substrate, based on the difference of the plasmon resonance process of the randomness of the densely stacked nanostructure itself, based on the transmission imaging to construct unclonable information, and to achieve capacity expansion by using efficient and simple coding strategies in two dimensions of wavelength and polarization.

[0009] In order to achieve the above-mentioned purpose, the present invention proposes an optical PUF chip based on a plasmon random structure, comprising: a substrate, on which a plurality of densely arranged nanostructures are obtained by evaporation using a porous nanofilm as a deposition auxiliary template, based on the randomness and local defects of the template and different gradients of angular deposition, the nanostructures have random differences in size, dimension and distribution, and present different plasmon resonance effects, and the nanostructures include: a dense particle structure with statistical differences determined by the template aperture and a clustered island structure determined by random defects in the template.

[0010] A further technical solution of the present invention is that the substrate is a transparent material or a flexible film;

[0011] The transparent material includes quartz or glass;

[0012] The flexible membranes are based on PDMS, PMMA or hydrogel.

[0013] To achieve the above objectives, the present invention also proposes an optical PUF chip reading system based on a plasmon random structure, and the optical PUF chip reading system based on a plasmon random structure is applied to the optical PUF chip based on a plasmon random structure as described above, and the optical PUF chip reading system based on a plasmon random structure includes a broadband light source, a wavelength selection device, a polarizer, a half-wave plate, an objective lens and an image sensor arranged in sequence, and the optical PUF chip is located between the half-wave plate and the objective lens.

[0014] To achieve the above objectives, the present invention also proposes an optical PUF chip reading system based on a plasmon random structure, and the optical PUF chip reading system based on a plasmon random structure is applied to the optical PUF chip based on a plasmon random structure as described above, and the optical PUF chip reading system based on a plasmon random structure includes a light source and an image sensor, the optical PUF chip is bonded to the image sensor, and the light of the light source directly irradiates the optical PUF chip.

[0015] To achieve the above object, the present invention further proposes a method for evaluating the coding capacity of an optical PUF chip based on a plasmon random structure, the method being applied to the optical PUF chip based on a plasmon random structure as described above, the method comprising the following steps:

[0016] Step S10, acquiring a PUF transmission image received by an image sensor;

[0017] Step S20, performing a hash algorithm on the PUF transmission image to generate a frequency coefficient matrix;

[0018] Step S30, extracting low-frequency information from the frequency coefficient matrix based on information features to obtain a two-dimensional pixel matrix with a resolution of M×M, where M is the number of pixels;

[0019] Step S40, binarizing the two-dimensional pixel matrix, comparing it with a preset frequency coefficient threshold, setting coefficients greater than 0 to 1, and setting coefficients less than 0 to 0, and the preset frequency coefficient threshold is 0;

[0020] Step S50, generate a single capacity of 2 M×M PUF key, M is an integer greater than 20 and less than P / 2, and P is the minimum image resolution.

[0021] A further technical solution of the present invention is that before step S10, the process includes:

[0022] Step S00, setting the excitation light source wavelength channel 1-i, polarization channel 1-j, and fixing a certain wavelength m and polarization n of the excitation light source (1≤m≤i, 1≤n≤j);

[0023] After step S50, the following steps are further included:

[0024] Step S60, multiplexing using multi-channel wavelength and polarization to obtain a maximum coding capacity of 2 M×M×i×j PUF key.

[0025] A further technical solution of the present invention is that after step S60, the following steps are further included:

[0026] Step S70: Evaluate the uniformity of the PUF key.

[0027] A further technical solution of the present invention is that the step S70 includes: selecting N PUF keys with the same parameters integrated on the same chip, and calculating the bit uniformity metric of the PUF keys using the following formula, wherein the value range of N is generally 5-100:

[0028] Its A, K i and n represents the i-th binary bit of the key and the key size.

[0029] A further technical solution of the present invention is that the step S70 includes:

[0030] Step S80: verifying the randomness of the N PUF keys with the same parameters integrated on the same chip.

[0031] The optical PUF chip, reading system and coding capacity evaluation method based on the plasmon random structure of the present invention have the following beneficial effects:

[0032] The present invention realizes an array-type integrated optical PUF architecture on a transparent substrate. Based on the randomness of densely stacked nanostructures and the differences in the photoinduced plasmon resonance process, unclonable information is constructed based on transmission imaging, and capacity expansion is achieved using efficient and simple wavelength and polarization coding strategies. This can significantly reduce costs and speed up the mass production of plasmon chips. It can be integrated with personal smartphones and other devices without the need for additional equipment. The coding capacity and security can be improved in a simple and direct way, and the requirements for label coding capacity and information verification in different fields can be met. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the three-dimensional structure of the optical PUF chip based on the plasmon random structure of the present invention;

[0034] Figure 2 is a top view of an optical PUF chip based on a plasmon random structure of the present invention;

[0035] Figure 3 It is a top view of the optical PUF chip based on the random structure of plasmons in the present invention in a microscopic state;

[0036] Figure 4 It is a side view of the optical PUF chip based on the plasmon random structure of the present invention in a microscopic state;

[0037] Figure 5 It is a schematic diagram of the preparation process of the optical PUF chip based on the plasmon random structure of the present invention;

[0038] Figure 6 is a schematic diagram of an optical PUF chip reading system based on a plasmon random structure of the present invention;

[0039] Figure 7 Schematic diagram of another scheme of the optical PUF chip reading system based on the plasmon random structure of the present invention;

[0040] Figure 8 It is a flow chart of a first embodiment of a method for evaluating coding capacity of an optical PUF chip based on a plasmon random structure of the present invention;

[0041] Fig. 9 It is a flow chart of a second embodiment of a method for evaluating coding capacity of an optical PUF chip based on a plasmon random structure according to the present invention;

[0042] Fig.10 This is a schematic diagram of the structure of a PUF chip prepared using gold as a target material;

[0043] Fig.11 This is a schematic diagram of imaging a sample using a scanning electron microscope at a 50 μm scale;

[0044] Fig.12 This is a schematic diagram of imaging a sample using a scanning electron microscope at a 5μm scale;

[0045] Fig.13 is a schematic diagram of the extinction spectrum when the deposition angle 107 is 8° and 16°;

[0046] Fig.14 This is a schematic diagram of the original random two-dimensional scattering image captured by the CMOS camera for a PUF tag with a deposition angle of 8° under the conditions of a fixed wavelength of 580nm and an excitation light source with a polarization of 0°;

[0047] Fig.15 It is a schematic diagram of the frequency coefficient matrix distribution of the transmission image after the Phash algorithm;

[0048] Fig.16 This is a schematic diagram of randomness verification of 15 PUF keys with the same parameters on the same chip;

[0049] Fig.17 This is a schematic diagram of the distribution of intra-chip and inter-chip Hamming distances between 15 PUF chips processed with the same parameters when the deposition angle is 8°. The embedded small figure shows the detailed information of the intra-chip Hamming distance.

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0052] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0053] The present invention proposes an optical PUF chip based on a plasmon random structure, which is an array-type integrated optical PUF architecture implemented on a transparent substrate. It constructs unclonable information based on transmission imaging based on the differences in the randomness of the densely stacked nanostructures themselves. Finally, it uses efficient and simple wavelength and polarization coding strategies to achieve capacity expansion. The present invention can be applied to high-end product security anti-counterfeiting labels, random key generation and storage, device identity authentication, random number generation, optical encryption communication and verification, etc.

[0054] like Figures 1 to 5 As shown, the optical PUF chip based on the random structure of plasmons of the present invention includes: a substrate 101, a densely arranged nanostructure obtained by evaporation using a porous nanofilm as a deposition auxiliary template on the substrate 101, based on the randomness and local defects of the template and the different gradients of angular deposition, the nanostructure has random differences in size, dimension and distribution, and presents different plasmon resonance effects, and the nanostructure includes: a dense particle structure 104 with statistical differences determined by the template aperture and a clustered island structure 105 determined by the random defects in the template.

[0055] The substrate 101 is a transparent material or a flexible film. The transparent material includes quartz or glass. The flexible film is based on PDMS, PMMA or hydrogel.

[0056] The present invention uses a porous nanofilm as a deposition auxiliary template, and a densely arranged nanostructure can be prepared on a substrate 101 over a large area. By patterning the quartz substrate, the location information of each PUF tag is defined to form a PUF array. Based on the randomness and local defects of the template and the different gradients of angle deposition, the size, shape and distribution of the nanoparticles deposited between each PUF tag vary greatly, where the on-chip deposition structure is mainly divided into two types, one is a small particle structure 104 determined by the template aperture, and the other is a cluster structure 105 determined by random defects in the template. The localized surface plasmon resonance (LSPR) of the gold nanostructure in the visible wavelength range and the strong absorption it produces, combined with its high-density arrangement and high signal intensity, the present invention avoids the dark field scattering imaging technology required in the traditional characterization of a small amount of nanoparticles, and can easily extract spatial non-uniformity information using simple or even portable equipment. The image can be frequency-domain selected and binarized using the pHash algorithm to generate the corresponding PUF key. At the same time, by utilizing the ultra-high sensitivity of PUF keys to wavelength and polarization, randomness can be ensured while facilitating the construction of low-cost and high-reliability coding schemes, thereby achieving the construction of a more secure key management system and the formation of a larger capacity database.

[0057] Figure 1 and Figure 2 The overall architecture of the optical PUF chip based on the random structure of plasmons of the present invention is shown. PUF chips are often centimeters or even larger in size, which is convenient for large-scale, batch and unified preparation of hundreds or thousands of PUF tags. In subsequent applications, the chip can be further divided in the form of cutting. The chip substrate 101 is preferably a transparent material, including common quartz, glass, and some organic polymer materials, including polystyrene. The substrate 101 can also be made of flexible films based on PDMS, PMMA, hydrogel, etc. to adapt to the integration process of different products and scenarios and expand the scope of application.

[0058] In addition to the heterogeneity within the unit, the on-chip nanostructure can also be designed with gradient differences between each unit, such as differences in extinction coefficients at a specific working wavelength. Nanostructure unit 102 has a smaller characteristic structure size than nanostructure unit 103, thus presenting plasmon resonance effects with different spatial responses and spectral responses. Figure 3 and Figure 4 As shown, from a microscopic perspective, the nanostructure has a dense particle structure 104 with extremely small scales of tens of nanometers and statistical differences, and there are also differences in clustered island structures 105 that exist in the form of random defects. The two together determine the final imaging information.

[0059] like Figure 5As shown, the preparation process of the optical PUF chip based on the random structure of plasmons of the present invention adopts template-assisted evaporation on the substrate 101. The target material 106 is not limited to gold, and other precious metals that can produce plasmon resonance effects such as silver, platinum, and aluminum are also applicable. In addition, some oxides such as silicon dioxide, titanium dioxide, and aluminum oxide with Mie resonance can also realize the function of the optical PUF chip by similar principles. The evaporation method includes conventional physical deposition (thermal evaporation, magnetron sputtering, etc.) and chemical deposition. The evaporation can be in a conventional vertical direction, or shadow deposition can be used. The angle 107 between the deposition direction and the vertical direction of the substrate can be used as a control parameter, preferably 0°-15°. The template is a porous nanofilm structure, preferably a treated anodized aluminum film. The pore size is preferably tens to hundreds of nanometers, which determines the morphology of the small particle structure 104. The position of some template defects determines the morphology of the clustered island structure 105.

[0060] The optical PUF chip based on the random structure of plasmons in the present invention realizes an array-type integrated optical PUF architecture on a transparent substrate. Based on the randomness of the densely stacked nanostructures themselves and the differences in the plasmon resonance process of light-induced excitation, unclonable information is constructed based on transmission imaging, and capacity expansion is achieved using efficient and simple wavelength and polarization coding strategies. This can significantly reduce costs and speed up chip production. It can be integrated with personal smartphones and other devices without the need for additional equipment, and can improve coding capacity and security in a simple and direct manner, meeting the needs of different fields for tag coding capacity and information verification.

[0061] To achieve the above objectives, the present invention also proposes an optical PUF chip reading system based on a plasmon random structure, and the optical PUF chip reading system based on a plasmon random structure is applied to the above optical PUF chip based on a plasmon random structure.

[0062] like Figure 6 As shown, the optical PUF chip reading system based on the plasmon random structure includes a broadband light source 201, a wavelength selection device 202, a polarizer 203, a half-wave plate 204, an objective lens 206 and an image sensor 207 arranged in sequence, and the optical PUF chip 205 is located between the half-wave plate 204 and the objective lens 206.

[0063] The broadband light source 201 forms a narrowband excitation light at a characteristic central wavelength through a wavelength selection device 202 such as a monochromator and an adjustable filter. The polarization state of the excitation light is controlled by a polarizer 203 and a half-wave plate 204, and then incident on an optical PUF chip 205. The imaging of a specific individual PUF tag can be achieved by focusing through an objective lens 206, and the final imaging is completed by an image sensor 207 such as a CCD or CMOS.

[0064] As another embodiment, Figure 7 As shown, the optical PUF chip reading system based on plasmon random structure is a handheld portable solution. The optical PUF chip reading system based on plasmon random structure includes a light source and an image sensor. The optical PUF chip is bonded to the image sensor, and the light from the light source directly irradiates the optical PUF chip.

[0065] This solution uses a miniaturized light source 208 such as LED, SLD, LD, etc. to directly illuminate the optical PUF chip 205, and the optical PUF chip 205 is attached to the image sensor 207 itself, so that imaging is completed in the form of an objective lens.

[0066] To achieve the above object, the present invention also proposes a coding capacity evaluation method for an optical PUF chip based on a plasmon random structure, and the method is applied to the optical PUF chip based on a plasmon random structure as above, such as Figure 8 As shown, the first embodiment of the coding capacity evaluation method of the optical PUF chip based on the plasmon random structure of the present invention includes the following steps:

[0067] Step S10, acquiring a PUF transmission image received by an image sensor;

[0068] Step S20, performing a hash algorithm on the PUF transmission image to generate a frequency coefficient matrix;

[0069] Step S30, extracting low-frequency information from the frequency coefficient matrix based on the information feature to obtain a two-dimensional pixel matrix with a resolution of M×M, where M is the number of pixels;

[0070] Step S40, binarizing the two-dimensional pixel matrix, comparing it with a preset frequency coefficient threshold, setting coefficients greater than 0 to 1, and coefficients less than 0 to 0, and the preset frequency coefficient threshold is 0;

[0071] Step S50, generate a single capacity of 2 M×M PUF key, M is an integer greater than 20 and less than P / 2, and P is the minimum image resolution.

[0072] Please refer to Fig. 9 In this embodiment, before step S10, the following steps are included:

[0073] Step S00, setting the excitation light source wavelength channel 1-i, polarization channel 1-j, and fixing a certain wavelength m and polarization n of the excitation light source (1≤m≤i, 1≤n≤j);

[0074] After step S50, the following steps are also included:

[0075] Step S60, multiplexing using multi-channel wavelength and polarization to obtain a maximum coding capacity of 2 M×M×i×j PUF key.

[0076] In this embodiment, after step S60, the following steps are further included:

[0077] Step S70: Evaluate the uniformity of the PUF key.

[0078] In this embodiment, step S70 includes: selecting N PUF keys with the same parameters integrated on the same chip, and calculating the bit uniformity metric of the PUF key using the following formula, where the value range of N is 5-100:

[0079]

[0080] Among them, K i and n represents the i-th binary bit of the key and the key size.

[0081] In this embodiment, the steps after step S70 include:

[0082] Step S80, verifying the randomness of N PUF keys with the same parameters integrated on the same chip.

[0083] The following further describes the coding capacity evaluation method of the optical PUF chip based on the plasmon random structure of the present invention.

[0084] The coding capacity evaluation method of the optical PUF chip based on the plasmon random structure of the present invention uses the perceptual hash algorithm (Phash) based on two-dimensional discrete cosine transform (DCT) of MATLAB to extract the PUF key. Figure 8 The flowchart of the first embodiment of the coding capacity evaluation method of the optical PUF chip based on the plasmon random structure of the present invention is shown. The PUF transmission image received by the image sensor is processed by the perceptual hash algorithm (phash algorithm) to generate a frequency coefficient matrix. The matrix contains both low-frequency coefficients that store information and high-frequency coefficients that are related to minor details but do not affect the main changes in the image itself. In subsequent processing, these high-frequency coefficients will be ignored, and key features such as information in the low-frequency range, such as local spots, wrinkle-like patterns, and non-uniform backgrounds, are retained in the form of a matrix. Based on the information features, low-frequency information can be extracted from the frequency coefficient matrix. The size of the two-dimensional pixel matrix is ​​M×M resolution, where M is the number of pixels. By setting the frequency coefficient threshold to 0, the two-dimensional pixel matrix is ​​binarized, and the coefficients greater than 0 are set to 1, and those less than 0 are set to 0. The capacity corresponding to the generated PUF key is 2 M×M The value of M can be any integer, and its value is 20<M<P / 2, where P is the minimum image resolution.

[0085] also, Fig. 9 The figure is a flow chart of the second embodiment of the coding capacity evaluation method of the optical PUF chip based on the plasmon random structure of the present invention. The flow chart shows the multi-channel coding strategy scheme.

[0086] Since the optical response of the plasmon chip to different wavelengths and polarizations of the excitation light source is different, for the same optical PUF chip, a new PUF key will be generated when the wavelength or polarization of the excitation light source changes, which provides new possibilities for expanding the coding capacity. Set the excitation light source wavelength channel 1-i and polarization channel 1-j, fix a certain wavelength m and polarization n of the excitation light source (1≤m≤i, 1≤n≤j), obtain the transmission image of the optical PUF chip under this condition through the optical system, and then use Fig. 9 The Phash algorithm process obtains a single capacity of 2 M×M Key. If multiple channels of wavelength and polarization are used for multiplexing, the maximum encoding capacity that can be obtained by a single PUF is theoretically 2 M×M×i×j It should be noted that the coding capacity here only considers the binary frequency intensity distribution. In order to expand the coding capacity and prevent duplication, the frequency intensity of each point can be encoded (such as octal, decimal, hexadecimal, etc.) in the present invention, thereby expanding the PUF key capacity.

[0087] An example scheme of a PUF array based on plasmonic gold nanoparticles is shown below.

[0088] Fig.10 A PUF chip prepared with gold as the target material is shown. The chip substrate uses laser direct writing technology to define pixelated PUF areas with a size of ~10×10mm and a spacing of ~200μm, containing a total of 324 PUF areas. The porous nanofilm structure is an anodized aluminum film with a film thickness of ~200nm and an average pore size of ~80nm. Figure 11 to Figure 12 Demonstrated imaging of samples using scanning electron microscopy at 50μm and 5μm scales. Fig.11 The white spots in the middle are caused by the defects in the porous nanofilm structure during the preparation process, which leads to the formation of clustered gold nanoparticles. Fig.12 The gold nanoparticle cluster area and the array area can be more clearly distinguished. Fig.13The extinction spectra are shown when the deposition angle 107 is 8° and 16°. Changing the deposition angle 107 will cause the particle size of the gold nanoparticles to change. The total particle size statistics corresponding to the two typical deposition angles of 8° and 16° are 60±20nm and 25±20nm, respectively. Among them, a smaller deposition angle 107 will result in nanoparticles with a larger overall size. At this time, the corresponding plasmon resonance wavelength is in a relatively long-wave position, resulting in a relatively larger extinction ratio. On the contrary, a larger deposition angle can result in an overall smaller nanoparticle size, and the corresponding plasmon resonance wavelength is in a relatively short-wave position.

[0089] Fig.14 It is the original random two-dimensional scattering image captured by the CMOS camera under the conditions of a fixed wavelength of 580nm and an excitation light source with a polarization of 0° for a PUF tag with a deposition angle of 8°. The intensity distribution of each pixel value is 0 to 255. Fig.15 The frequency coefficient matrix distribution of the transmission image after the Phash algorithm is shown. Set the matrix threshold to 0 and select the M value to 30. Fig.16 The PUF key of size 30×30 extracted from the transmission image is shown. In order to better evaluate the uniformity of the PUF key, the present invention selects 15 PUFs with the same parameters integrated on the same chip. The bit uniformity metric is calculated using the following formula:

[0090]

[0091] Where K i and n represents the i-th binary bit and key size of the key, and the average value of 15 PUF keys is 0.5122. It is proved that the PUF key generated by the plasmonic gold nanoparticle chip through the Phash algorithm has a very ideal uniformity (the ideal value is 0.5).

[0092] Fig.17 The randomness test of 15 PUF keys with the same parameters on the same chip is demonstrated. The NIST (National Institute of Standards and Technology) SP 800-22 standard is used here to evaluate the randomness of the generated PUF keys. The 15 PUF keys are processed to form an encryption key sequence with a length of 13500 bits (15×30×30 bits). The first 12800 bits are selected and divided into 100 groups of 128 bits each. According to the calculation of the required number of bits, the calculation is Fig.17 P values ​​of 9 tests. Each set of data is regarded as a round of test, and for each round of test, if the P value is greater than 0.01, it is granted a pass. The success rate of all tests is above 92%, proving the randomness and unpredictability of PUF keys.

[0093] In actual use, PUF tags need to be repeatedly verified, which requires good reproducibility between readings of the same tag and obvious differences between different tags. The present invention uses normalized Hamming distance to quantify the similarity between PUF keys. For PUFs prepared with the same process parameters, the calculated Hamming distance histogram statistics are obtained by Gaussian fitting. The mean μ and standard deviation σ of the fitted Gaussian curve are obtained. Since all pixels constituting the PUF key are not completely independent of each other, the present invention can also use independent bits (i.e., degrees of freedom, defined as To determine the encoding capability of the PUF key, the encoding capability of the PUF key is

[0094] The optical PUF chip coding capacity evaluation method based on the plasmon random structure of the present invention realizes an array-type integrated optical PUF architecture on a transparent substrate, constructs unclonable information based on transmission imaging based on the randomness of the densely stacked nanostructures themselves and the differences in the plasmon resonance process of light-induced excitation, and utilizes the two efficient and simple coding degrees of freedom of wavelength and polarization to achieve capacity expansion, which can significantly accelerate the mass production of plasmon chips and can be integrated with personal smart phones and other devices without the need for additional equipment. The coding capacity and security can be improved in a simple and direct way, and can meet the needs of different fields for label coding capacity and information verification.

[0095] The optical PUF chip coding capacity evaluation method based on the plasmon random structure of the present invention realizes an array-type integrated optical PUF architecture on a transparent substrate, constructs unclonable information based on transmission imaging based on the randomness of the densely stacked nanostructures themselves and the differences in the plasmon resonance process of light-induced excitation, and utilizes the two efficient and simple coding degrees of freedom of wavelength and polarization to achieve capacity expansion, which can significantly accelerate the mass production of plasmon chips and can be integrated with personal smart phones and other devices without the need for additional equipment. The coding capacity and security can be improved in a simple and direct way, and can meet the needs of different fields for label coding capacity and information verification.

[0096] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An optical PUF chip based on a plasmon random structure, characterized in that: include: A substrate, on which a plurality of densely arranged nanostructures are obtained by evaporation using a porous nanofilm as a deposition auxiliary template. Based on the randomness and local defects of the template and the different gradients of angular deposition, the nanostructures have random differences in size, dimension and distribution, and present different plasmon resonance effects. The nanostructures include: a dense particle structure with statistical differences determined by the template aperture and a clustered island structure determined by random defects in the template.

2. The optical PUF chip based on plasmon random structure according to claim 1, characterized in that: The substrate is a transparent material or a flexible film; The transparent material includes quartz or glass; The flexible membranes are based on PDMS, PMMA or hydrogel.

3. An optical PUF chip reading system based on a plasmon random structure, characterized in that: The optical PUF chip reading system based on plasmon random structure is applied to the optical PUF chip based on plasmon random structure as described in any one of claims 1 or 2, and the optical PUF chip reading system based on plasmon random structure includes a broadband light source, a wavelength selection device, a polarizer, a half-wave plate, an objective lens and an image sensor arranged in sequence, and the optical PUF chip is located between the half-wave plate and the objective lens.

4. An optical PUF chip reading system based on a plasmon random structure, characterized in that: The optical PUF chip reading system based on plasmon random structure is applied to the optical PUF chip based on plasmon random structure as described in any one of claims 1 or 2, and the optical PUF chip reading system based on plasmon random structure includes a light source and an image sensor, the optical PUF chip is bonded to the image sensor, and the light of the light source directly irradiates the optical PUF chip.

5. A method for evaluating the coding capacity of an optical PUF chip based on a plasmon random structure, characterized in that: The method is applied to the optical PUF chip based on the plasmon random structure according to any one of claims 1 to 4, and the method comprises the following steps: Step S10, acquiring a PUF transmission image received by an image sensor; Step S20, performing a hash algorithm on the PUF transmission image to generate a frequency coefficient matrix; Step S30, extracting low-frequency information from the frequency coefficient matrix based on information features to obtain a two-dimensional pixel matrix with a resolution of M×M, where M is the number of pixels; Step S40, binarizing the two-dimensional pixel matrix, comparing it with a preset frequency coefficient threshold, setting coefficients greater than 0 to 1, and setting coefficients less than 0 to 0, and the preset frequency coefficient threshold is 0; Step S50, generate a single capacity of 2 M×M PUF key, M is an integer greater than 20 and less than P / 2, and P is the minimum image resolution.

6. The coding capacity evaluation method of the optical PUF chip based on the plasmon random structure according to claim 5 is characterized in that: The step S10 includes: Step S00, setting the excitation light source wavelength channel 1-i, polarization channel 1-j, and fixing a certain wavelength m and polarization n of the excitation light source (1≤m≤i, 1≤n≤j); After step S50, the following steps are further included: Step S60, multiplexing using multi-channel wavelength and polarization to obtain a maximum coding capacity of 2 M×M×i×j PUF key.

7. The coding capacity evaluation method of the optical PUF chip based on the plasmon random structure according to claim 6 is characterized in that: After step S60, the following steps are further included: Step S70: Evaluate the uniformity of the PUF key.

8. The coding capacity evaluation method of the optical PUF chip based on the plasmon random structure according to claim 7 is characterized in that: The step S70 includes: selecting N PUF keys with the same parameters integrated on the same chip, and calculating the bit uniformity metric of the PUF keys using the following formula, where the value range of N is usually 5-100: Among them, K i and n represents the i-th binary bit of the key and the key size.

9. The coding capacity evaluation method of the optical PUF chip based on the plasmon random structure according to claim 8 is characterized in that: The step S70 then includes: Step S80: verifying the randomness of the N PUF keys with the same parameters integrated on the same chip.

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