Selected Bit-Line Current PUF: Implementation of Hardware Security Primitive Based on a Memristor Crossbar Array

Abstract

In this paper, a physical unclonable function (PUF), a type of hardware security device, is proposed to overcome the limitations of existing security schemes. We fabricated a 32×32 crossbar array using TiOx/Al2O3–based memristors and analyzed its electrical characteristics, including its set voltage distribution. The memristor switching characteristics model is described in a simplified space-charge-limited current (SCLC) regime. Based on this I-V model, we designed selected bit-line current PUFs (SBC-PUFs) with 32×32, 64×64, and 128×128 crossbar arrays. The entropy source of these PUFs is the set voltage deviation in the fabricated memristors. Due to these characteristics, we can exploit the broad resistance distribution near the switching region, including the internal resistance distributions of the high resistance state (HRS) and low resistance state (LRS). The SBC-PUF performance was evaluated for randomness/uniformity, correctness/reliability, and uniqueness by calculating the Hamming weight and intra/inter Hamming distance of challenge-response pairs (CRPs). The designed structure demonstrates high-security performance due to the high value of these indicators and the large number of CRPs. Furthermore, the devised PUF has a higher prediction error rate than the arbiter PUF in machine learning attacks. This paper verified that the SBC-PUF using the memristor of the crossbar array structure is safe enough to be used for hardware security.