Concealable physical unclonable functions using vertical NAND flash memory
Sungho Park, Ryun‐Han Koo, Yeongheon Yang, Jiseong Im, Jonghyun Ko, Jong‐Ho Lee
Abstract
Physical Unclonable Functions (PUFs) can address the demand for enhanced hardware security. Vertical NAND (V-NAND) flash memory is the most commercialized non-volatile memory. However, it has been optimized to reduce cell-to-cell variation for stable data storage, which presents challenges for its application as a PUF, as PUFs inherently rely on such variations. Here, we propose a concealable PUF using V-NAND flash memory by generating PUF data through weak Gate-Induced-Drain-Leakage (GIDL) erase. The differences in doping depth among V-NAND strings arising from the fabrication cause variations in GIDL erase performance. The resulting V-NAND PUF demonstrated ideal security characteristics while maintaining 100% accuracy under variations in read count and temperature. Concealment is achieved by overwriting the PUF data with other data, and perfect conceal-reveal characteristics are maintained over 102 cycles. Concealable V-NAND PUF not only prevents attacks when the PUF is not in use but also allows the memory to be utilized as storage. It is a challenge to optimize vertical NAND (V-NAND) flash memory for physical unclonable function (PUF) applications. Here, the authors present a method for generating PUF data using gate-induced-drain-leakage erase, improving reliability of V-NAND flash memory-based PUFs and adding concealable characteristics.