Yale Computer and Engineering Seminar Series
Ulrich Rührmair, Horst Görtz Institute for IT-Security, Ruhr-University Bochum
Host: Prof. Jakub Szefer, Dept. of Electrical Engineering, Yale University
Title: Physical Disorder for IoT – Security
At sufficiently small length scales, for example in the nanometer regime, practically all physical objects are not perfectly smooth or regularly shaped – rather, they possess a random, imperfect, or physically disordered fine structure. The occurrence of this phenomenon is usually regarded as a nuisance: As two illustrating examples, think of circuit designers trying to downscale their technologies, or of physicists intending to fabricate perfect nanostructures.
Over the last decades, though, celebrated research has revealed that physical disorder can actually be exploited very beneficially in a security context. Its occurrence naturally provides each hardware device with its own, individual and unclonable physical fingerprint. This is useful, for example, in establishing individual keys in low-cost systems without non-volatile memory. It can also identify hardware remotely over digital communication lines without classical keys, leading to security improvements against standard key-extracting attacks. Or, finally, it can enable advanced protocols like key exchange and oblivious transfer without classical number-theoretic assumptions on the hardness of the factoring or discrete logarithm problem.
In discussing these and other examples, our talk will survey the broad literature on physical unclonable functions (PUFs) that has evolved over the last years. It will illustrate the employment of physical disorder as an unexpected, but extremely powerful security resource. Special emphasis will thereby be given to low-cost and low-resource applications in the Internet of Things (IoT).
Ulrich Rührmair holds an MSc in mathematics from Oxford University, a PhD in computer science from TU Berlin, and a PhD in electrical engineering from TU Munich. At the latter institution, he founded and for several years led the so-called physical cryptography project. His research generally deals with physical unclonable functions, disorder-based security, and complexity theory at large. Most recently, his investigations have focused on the development of novel disorder-based primitives beyond PUFs. This includes SIMPL systems, which are a public key version of PUFs, or so-called Virtual Proofs of Reality, whose aim is to prove physical statements over digital communication channels without using classical secret keys or classical sensors. Ulrich has written over 50 papers on the topic, has received numerous awards and scholarships. He has served on multiple program committees, including IEEE S&P, CHES and HOST.