The Resistance Analysis Attack and Security Enhancement of the IMC LUT Based on the Complementary Resistive Switch Cells

The resistive random access memory (RRAM) based in-memory computing (IMC) is an emerging architecture to address the challenge of the "memory wall" problem. The complementary resistive switch (CRS) cell connects two bipolar RRAM elements anti-serially to reduce the sneak current in the crossbar array. The CRS array is a generic computing platform, for the arbitrary logic functions can be implemented in it. The IMC CRS LUT consumes fewer CRS cells than the static CRS LUT. The CRS array has built-in polymorphic characteristics because the correct logic function cannot be distinguished based on the circuit layout. However, the logic state of every CRS cell can be readout after each operation. It helps the attacker to recover the correct function of the IMC CRS LUT. This work discusses the resistance analysis attack of the IMC LUT based on the CRS array. The proposed resistance analysis attack method is able to be applied to different computation styles based on the CRS array, such as the CRS IMPLY, CRS NOR-OR/NAND-AND, and so on. The attacker can recover the logic function of the LUT by tracing the states of CRS cells. Furthermore, an improved IMC CRS LUT method is proposed and discussed to enhance security. The simulation and analysis results show that the improved IMC CRS LUT can resist various attacks, and it maintains the polymorphic characteristics of the IMC CRS LUT. And the N-bit full adder circuit based on the improved IMC CRS NOR-OR LUTs achieves the best performance compared with the previous counterparts.