Strachey Lectures

This lecture explores the topic of secret communication through the design and deployment of CoverDrop, a secure communication system designed in collaboration with The Guardian. The history of secret communication has been driven by the need for both confidentiality and anonymity. Over the last thirty years we’ve seen significant progress in the digital space, with encryption now widely deployed on the web and in personal messaging apps. Protecting the identity of communicating parties is comparatively underexplored, despite the fact that the timing, frequency, and volume of network traffic can often reveal who is talking to whom, even if the communication itself is encrypted. These technological developments also sit at the centre of a wider societal debate: secure communications are simultaneously essential to protect individual autonomy and foster commercial innovation, yet they can also pose serious operational challenges to law enforcement and the oversight of public safety.We will walk through the seven-year journey from our initial research idea to a real-world deployment that now serves as the default channel by which news sources and whistleblowers contact The Guardian. We’ll explore the technical hurdles that arise when providing confidential and plausibly deniable communication inside a news app at scale, and reflect on whether these technologies, and indeed other emerging ideas in the digital landscape, are an overall benefit to society. The Strachey Lectures are generously supported by OxFORD Asset Management

Trinity Term 2026 Strachey Lecture with Professor Srđan Čapkun, Hardening Digital Infrastructure: Resilient Positioning and Sovereign Smartphone Architectures. Recent global events have underscored how failures in isolation, redundancy, and control can jeopardiseessential digital functions. A critical challenge remains: how do we harden systems for higher resiliency, personal and societal control while maintaining compatibility with existing ecosystems? In this talk, I explore this in two example settings. First, I address the systemic vulnerabilities of current satellite positioning systems. By integrating novel protocols hardened at the physical layer, I demonstrate a path toward a robust, feature-rich, wide-area positioning infrastructure. Second, I introduce a novel security architecture that brings true digital sovereignty to the modern smartphone. This deployable design allows users to run 'several phones in one' (e.g. isolating private and business environments), ensuring that sensitive applications and critical I/O remain protected even if the underlying OS is compromised. Ultimately, these designs return control to users and organisations, fostering a more resilient and free environment for digital innovation.

Hilary Term 2026 Strachey Lecture with Professor Ion Stoica, An AI stack: from scaling AI workloads to evaluating LLMs Large language models (LLMs) have taken the world by storm, enabling new applications, intensifying GPU shortages, and raising concerns about the accuracy of their outputs. In this talk, I will present several projects I have worked on to address these challenges. Specifically, I will focus on Ray, a distributed framework for scaling AI workloads, vLLM and SGLang, two high-throughput inference engines for LLMs, and LMArena, a platform for accurate LLM benchmarking. I will conclude with key lessons learned and outline directions for future research.

MT25 Strachey Lecture - Professor Rafail Ostrovsky: Advances in Garbled Circuits Nearly 40 years ago, Andy Yao proposed the construction of “Garbled Circuits,” which had an enormous impact on the field of secure computation -- both in theory and in practice. In Garbled Circuits, two parties agree on a Boolean circuit that they want to evaluate, where both parties have partial, disjoint inputs to the circuit, and neither party is willing to disclose to the other party anything but the output. In this talk, I will survey the state of the art for garbling schemes, including computing with Garbled Random Access Memory, the so-called GRAM constructions that were invented by Lu and Ostrovsky in 2013, as well as more recent progress, including the GRAM paper by Heath, Kolesnikov and Ostrovsky, which received the best paper award in Eurocrypt 2022. I will also discuss Garbled Circuits in the malicious setting, where parties try to deviate arbitrarily from the prescribed protocol execution to gain additional information, and will review some of the latest advances in this area. The talk will be self-contained and accessible to the general audience.

Kevin Buzzard: Will Computers prove theorems? Will computers one day replace human mathematicians? Is this just around the corner, or decades away? Can neural networks spot patterns which humans have missed? Currently language models are great for brainstorming big ideas but are very poor when it comes to details. Can integrating a language model with a theorem prover like Lean solve these problems? Is the modern mathematical literature riddled with errors, and is it feasible to hope that a machine might find and even fix them? Is it possible to teach a computer the proof of Fermat's Last Theorem? And what do mathematicians make of all this? I'll talk about how modern developments in AI and theorem provers are beginning to affect mathematics.