CCF: SHF: CORE: Small: Towards Systematic Quality Control of Physically Unclonable Functions (PUFs)

物理不可克隆功能（puf）是相对较新的设备，通常是电子设备，目前正在设计和研究作为各种安全应用程序的硬件安全原语的潜在用途。电子puf的工作原理是利用芯片制造过程中一些固有的随机性，这种随机性产生的模拟特征带有轻微的随机变化，这些变化结合在一起产生数字功能。这种随机性在传统的芯片制造过程中通常被认为是不可取的，在这里被利用，当与模拟-数字过程相结合时，实现了“挑战-响应”布尔函数。希望每个设备的挑战-响应对（CRPs）列表是唯一的，因此可以用于安全应用程序，如设备识别、身份验证和按需加密密钥生成。强大的puf保证了硬件尺寸的巨大CRP空间指数，因此能够在设备的整个生命周期中按需生成许多和/或非常长的密钥。尽管强大的puf具有吸引力，但很少有商业实现存在。为了实现这一点，1)如何正确地制造和测试强puf，以及2)一旦制造和测试，如何正确地将这些设备集成到安全协议中需要解决。后者得到了很好的研究；这个奖项的研究将集中在相对未被探索的前一个问题上。在这个项目中，两名来自互补领域（统计/信息理论和电子设计自动化/硬件安全）的教员将共同开发一个系统框架，用于测试、诊断、修复和加强强大的puf。他们将培训本科生和博士生进行硬件安全原语的测试和验证——对这一新领域有深刻理解的工程师对于美国未来值得信赖的IC设计和验证团队是不可或缺的。这项研究与现有的puf工作有很大的不同，这些工作主要集中在提出新的puf和评估其属性，或者基于puf的协议的安全攻击/防御。展望未来，随着国内芯片制造的增加，研究人员将重点放在实现PUF的承诺所需要的方面：1)为PUF实例、PUF生产线和PUF老化过程开发新的统计、本地故障模型；2)设计能够快速准确识别此类故障的测试和诊断技术。这可以反馈到电子设计自动化工具，迭代地加强PUF质量控制。这与现有的测试技术明显不同，现有的测试技术是根据黄金行为测试芯片。研究人员还将开发通过挑战选择修复故障、老化或不可靠PUF的技术，这些技术可能会被纳入PUF协议。这一行工作代表了对强大puf的巨大挑战空间的谨慎和统计动机的开发。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Physically Unclonable Functions (PUFs) are relatively new devices, often electronic, currently being designed and investigated for potential use as hardware security primitives for various security applications. Electronic PUFs work by exploiting some inherent randomness in the chip manufacturing process, which produces analog features with slight random variations that are combined to yield a digital function. This randomness, usually considered undesirable in traditional chip manufacturing processes, here is harnessed and, when coupled with an analog-to-digital process, realizes a "challenge-to-response" Boolean function. The hope is that each device's list of challenge-response-pairs (CRPs) is unique and hence may be used in security applications such as device identification, authentication, and on-demand cryptographic key generation. Strong PUFs promise a huge CRP space exponential in hardware size and hence able to generate, on demand, many and/or very long keys with minimal hardware throughout a device's lifespan. Despite the appeal of strong PUFs, few commercial realizations exist. To enable this, both 1) how to properly manufacture and test strong PUFs, and 2), once fabricated and tested, how to properly integrate such devices into security protocols need to be addressed. The latter is well studied; this award’s research will focus on the relatively unexplored former question. In this project, which brings together two faculty in complementary areas (statistics / information theory and electronic design automation / hardware security), the team will develop a systematic framework for the testing, diagnosing, repairing, and strengthening of strong PUFs. They will train undergraduate and Ph.D. students in testing and verification of hardware security primitives -- engineers with a deep understanding of this new area are indispensable for future trusted IC design and verification teams in the US. This research departs significantly from existing work on PUFs which has largely focused on either proposing new PUFs and evaluating their properties, or on security attacks / defenses of PUF-based protocols. Looking towards a future with ramped up domestic chip fabrication, the investigators focus on what would be needed to bring the promise of PUFs to fruition through: 1) developing new statistical, native fault models for PUF instances, PUF-production lines, and PUF-aging processes; 2) devising testing and diagnosing techniques able to quickly and accurately identify such faults. This could be fed back to electronic design automation tools to iteratively enhance PUF quality control. This differs markedly from existing testing techniques which test chips against a golden behavior. The investigators will also develop techniques to repair faulty, aging, or unreliable PUFs through challenge selection, which may be incorporated into PUF protocols. This line of work represents a careful and statistically motivated exploitation of the largely overlooked huge challenge space of strong PUFs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.