Physical unclonable functions (PUFs) are hardware-oriented primitives that exploit manufacturing variations to generate a unique identity for a physical system. Recent advancements showed how DRAM can be exploited to implement PUFs. DRAM PUFs require no additional circuits for PUF operations and can be used in most of the applications with resource-constrained nodes such as Internet of Things (IoT) networks. However, the existing DRAM PUF solutions either require to interrupt other functions in the host system, or provide unreliable responses due to their sensitiveness to the environmental conditions. In this paper, we propose EPUF, a novel strategy to extract random and unique features from DRAM cells to generate reliable PUF responses. In particular, we use the bitmap images of the binary DRAM values and their entropy features. We show via real device experiments that EPUF is approximately $1.7$ times faster than other state of the art solutions, achieves $100\%$ reliability, generates features with $47.79\%$ uniqueness, and supports a large set of CRP that leads to new potentials for DRAM PUF-based authentication. We also propose a lightweight authentication protocol based on EPUF, which not only provides far better security guarantees but also outperforms the state-of-the-art in terms of communication overhead and computational cost.

翻译：物理不可克隆函数（PUF）是一种利用制造工艺差异为物理系统生成唯一身份的硬件导向基元。最新研究表明，动态随机存取存储器（DRAM）可用于实现PUF。DRAM PUF无需额外电路即可执行PUF操作，可应用于物联网等资源受限节点的场景。然而，现有DRAM PUF方案要么需要中断主系统的其他功能，要么因对环境条件敏感而提供不可靠的响应。本文提出EPUF——一种从DRAM单元中提取随机且唯一特征以生成可靠PUF响应的新策略。具体而言，我们采用二进制DRAM值的位图图像及其熵特征。通过实际设备实验证明，EPUF速度约为现有最优方案的1.7倍，可靠性可达100%，特征唯一性为47.79%，并支持大规模挑战-响应对（CRP），为基于DRAM PUF的身份认证带来了新潜力。我们还提出一种基于EPUF的轻量级认证协议，该协议不仅提供更优的安全保障，在通信开销与计算成本方面也优于现有最优方案。