All-spin PUF: An Area-efficient and Reliable PUF Design with Signature Improvement for Spin-transfer Torque Magnetic Cell-based All-spin Circuits

Recently, spin-transfer torque magnetic cell (STT-mCell) has emerged as a promising spintronic device to be used in Computing-in-Memory (CIM) systems. However, it is challenging to guarantee the hardware security of STT-mCell-based all-spin circuits. In this work, we propose a novel Physical Unclonable Function (PUF) design for the STT-mCell-based all-spin circuit (All-Spin PUF) exploiting the unique manufacturing process variation (PV) on STT-mCell write latency. A methodology is used to select appropriate logic gates in the all-spin chip to generate a unique identification key. A linear feedback shift register (LFSR) initiates the All-Spin PUF and simultaneously generates a 64-bit signature at each clock cycle. Signature generation is stabilized using an automatic write-back technique. In addition, a masking scheme is applied for signature improvement. The uniqueness of the improved signature is 49.61%. With ± 20% supply voltage and 5°C to 105°C temperature variations, the All-Spin PUF shows a strong resiliency. In comparison with state-of-the-art PUFs, our approach can reduce hardware overhead effectively. Finally, the robustness of the All-Spin PUF against emerging modeling attacks is verified as well.