Round-Optimal Fully Secure Distributed Key Generation
Talk by Jonathan Katz
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.
Bio: 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.
