Random Nanofracture‐Enabled Physical Unclonable Function

Abstract

measures are primarily based on digital cryptographic signature or physical identification tag. [8][9][10] Digital cryptographic keys generated by pseudo-random mathematic functions need to be programmed into nonvolatile memory, accompanied with complicate tamper resilient devices to protect the keys from side-channel attacks. [11] Physical identification tags such as radiofrequency identification tags (RFID), [1,12] holograms, [13,14] graphical tags, [15] watermarks, [16] security inks, [17,18] barcode, [19][20][21] and chemical tag [9,22] have already been introduced to the consumer products for property protection. Nonetheless, these tags are made in deterministic processes, thus are vulnerable to clone attacks due to the low complexity and high predictability. More complex molecular tags could be adopted with an increase in cost, and can only be accessible in specialized laboratory. [23][24][25] To combat the rising tide of counterfeiting, physical unclonable function (PUF, or physical one-way function) has been introduced. [26,27] PUF is made from an indeterministic stochastic process, whose fingerprint-like response is difficult to predict upon external stimulus, thereby naturally immune to the clone attack. The sufficiently large complexity of PUF also renders it effective against brute force reverse engineering and tamper attack. [28] Conventional integrated circuit (IC) based PUFs typically utilize the inherent variations in the gate and wire time delays (e.g., arbiter PUF [29,30] and ring oscillator PUF [31] ) or local mismatches (e.g., SRAM PUF, [32] latch PUF, [33] flip-flop PUF [34] ) as the source of randomness. IC based PUF is convenient for on-chip integration owing to its CMOS compatibility, but is vulnerable to model building attack due to the relatively low complexity and large bit error rate. Emerging technologies with higher degree of complexity such as phase change memory, [35] interfacial magnetic anisotropy, [36] carbon nanotube field effect transistor, [37][38][39][40] memristor [41][42][43][44][45] are proposed with an exponential increase in cost and fabrication difficulty. Chemically synthesized PUFs can afford large encoding capacity, small footprint and low production cost by measuring readily detectable characteristics such as scattering speckle image, [26,[46][47][48] fingerprint like textures, [49][50][51] fluorescence or lasing [25,[52][53][54][55][56] surface enhanced Raman signature, [57][58][59][60] and unpredictable defects and patterns in 2D materials. [61,62] The complexity of chemical PUFs can easily be scaled Physical unclonable function (PUF) is promising for anticounterfeiting and security applications. In this paper, a PUF concept is demonstrated based on the stochastic generation of nanodot matrix via mechanical stripping of a gold film kirigami with arrayed nanoscale split-ring cuts. The random occurrence of nanofracture of metallic nanoconnection at split-ring parts results in unpredictable remaining (labeled as "1") or peeling-off (labeled as "0") of nanodots in ea...

Asymmetric Nanofractures Determined the Nonreciprocal Peeling for Self-Aligned Heterostructure Nanogaps and Devices

“…All fluctuation factors affecting the mechanical strength of the nanoconnection at the notch position, such as the geometry and grain boundaries, are attributed to a variable of equivalent fracture strength (S z ). 41 The intrinsic mechanism of the stripping process in this system is the competition between the through-film fracture strength of the Au film at the notch and Au/substrate interfacial failure. Cohesive zone models were used in the simulation, and the constitutive behavior of the interface was assumed as a bi-linear traction-separation law.…”

“…Cohesive zone models were used in the simulation, and the constitutive behavior of the interface was assumed as a bi-linear traction-separation law. 41,42 Figure 3d shows the displacement nephograms of two stripping processes. The dotted circles indicate the location of the notch.…”

“…The specific settings have been covered in our previous work. 41 The elastic modulus (E) and Poisson's ratio (v) are E Au = 38.2 GPa and v Au = 0.42. 47 Other parameters were set as follows: W Au/substrate = 1 × 10 −3 N/m, σ Au/substrate,n = 1 MPa, σ Au/substrate,τ = 1 MPa, W Au/tape = 4×10 −3 N/m, σ Au/tape,n =2 MPa, and σ Au/tape,τ = 2 MPa.…”

Randomly Induced Phase Transformation in Silk Protein‐Based Microlaser Arrays for Anticounterfeiting

“…Array-based optical PUF labels combine the deterministic readout sites with random signal outputs, [16] thus holding a promise to solve the contradiction between high randomness and convenient authentication. As a unique kind of optical signals, laser emissions featured with intense, fingerprint-like sharp peaks, [17] can function as the active light sources to deliver unique optical signature [18][19][20][21] and offer large coding capacities with rich information.…”

“…[7][8][9] Various optical features have been utilized to construct disordered systems for unique signatures, such as the random fluorescent patterns, [10,11] surface scattering, [12] optimal reflection, [13] random lasing, [14,15] and so on. The utilization of natural randomness enables these security labels easy to generate and difficult to duplicate; but the unpredictable signal extraction sites pose a challenge to efficient and convenient authentication, thereby restricting their practical anticounterfeiting applications.Array-based optical PUF labels combine the deterministic readout sites with random signal outputs, [16] thus holding a promise to solve the contradiction between high randomness and convenient authentication. As a unique kind of optical signals, laser emissions featured with intense, fingerprint-like sharp peaks, [17] can function as the active light sources to deliver unique optical signature [18][19][20][21] and offer large coding capacities with rich information.…”