We warmly invite you to Jonathan Katz’s public lecture on March 4, 2025, where he will discuss security challenges in distributed key generation, its round complexity, and protocols balancing efficiency and security.

• When? Tuesday, March 4, 9:30 - 11:00 am
• Where? FAV Hörsaal 1 Helmut Veith, Favoritenstraße 9-11, 1040 Vienna

Abstract

Protocols for distributed (threshold) key generation (DKG) in the discrete-logarithm setting have received a tremendous amount of attention in the past few years. Several synchronous DKG protocols have been proposed, but most such protocols are not fully secure: they either allow corrupted parties to bias the key, or are not robust and allow malicious parties to prevent successful generation of a key.

We explore the round complexity of fully secure DKG in the honest-majority setting where it is feasible. We show the impossibility of one-round, unbiased DKG protocols (even satisfying weaker notions of security), regardless of any prior setup. On the positive side, we show various round-optimal protocols for fully secure DKG offering tradeoffs in terms of their efficiency, necessary setup, and required assumptions.

About Jonathan Katz

Jonathan Katz recently joined Google as a Senior Staff Research Scientist, after more than 20 years as a professor at the University of Maryland where he also served as director of the Maryland Cybersecurity Center. He is a co-author of the widely used textbook “Introduction to Modern Cryptography” (now in its third edition) and also offers a free online course on cryptography through Coursera. Katz has received an Alexander von Humboldt Research Award, a UMD Distinguished Scholar-Teacher Award, and an ACM SIGSAC Outstanding Contribution Award. He is a fellow of the IACR and the ACM.

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