PUFiM: A Robust and Efficient FeFET-Based Security Solution Merging Physical Unclonable Function with Compute-in-Memory for Edge AI

Compute-in-memory (CiM) has become a promising candidate for edge AI by reducing data movements through insitu operations. However, this emerging computational paradigm also poses the vulnerability of model leakage as the weights are stored in plaintext for computing. While prior works have explored lightweight encryption methods, CiM is usually considered a separate module instead of a system component, leaving the origin of keys unclear and unprotected. Physical unclonable functions (PUFs) offer a potential origin of keys, but a comprehensive framework for securing key generation and delivery remains lacking. Besides, the complementary ciphertext storage incurs substantial costs and degrades the performance. This work proposes PUFiM, a robust and efficient security solution for edge computing based on ferroelectric FETs (FeFETs). For the first time, a strong PUF is synergized with CiM to enable authentication, key generation, and encrypted computations within a unified array for comprehensive protection. To achieve this synergization, a high-density hybrid storage and computation approach combining PUF and weight bits via multi-level cell (MLC) FeFETs is proposed. Besides, two PUF enhancement techniques and a novel mapping scheme are developed to improve security and efficiency further. Results show that PUFiM withstands PUF modeling attacks with up to $\mathbf{1 0 M}$ samples. Moreover, PUFiM reduces the inference accuracy by $\gt 60 \%$ under 95% key leakage and achieves $\gt 9.7 \times$ compute density and $\gt 1.2 \times$ energy efficiency improvement compared with the state-of-the-art SRAM/NVM secure CiMs.