Indistinguishability: The Stuff of Magic

2026–276 Allen School Distinguished Lecture Series Title: Indistinguishability: The Stuff of Magic Speaker: Cynthia Dwork (Harvard) Date: Thursday, November 5, 2026 Abstract: CS theory has given us many magical concepts, such as zero-knowledge proofs, pseudo-randomness, privacy-preserving data analysis, and public-key cryptography. These, and many others, share a common thread: their very definitions are based on indistinguishability, a core concept in complexity theory. Indistinguishability is a form of impossibility: encryptions of zero cannot be distinguished from encryptions of one; outputs of an analysis operating on a dataset D cannot be distinguished from outputs of an analysis operating on D-without-Me (or D-without-You). It is remarkable that this negative notion has proven to be such a generous instrument of algorithmic power. We will survey several flavors of indistinguishability and some recent, novel, applications. Bio: Cynthia Dwork, Gordon McKay Professor of Computer Science at Harvard and affiliated faculty at Harvard Law School and Department of Statistics, is known for her foundational role in the invention and development of differential privacy, non-malleable cryptography, and proofs of work; for launching the theory of algorithmic fairness; and for seminal contributions in lattice-based cryptography, distributed computing, and ensuring validity in adaptive data analysis. Her many honors include the US National Medal of Science, the Japan Prize, the Hamming Medal, and the Dijkstra, Gödel, Knuth, and Kanellakis Awards. She is a member of the US National Academy of Sciences and the National Academy of Engineering, and a Fellow of the American Academy of Arts and Sciences and the American Philosophical Society.