Joseph Bonneau
October 23, 2015 at 12:00 PM in 380 Soda Hall
Title: Provisions: Privacy-preserving proofs of solvency for Bitcoin exchanges
Bitcoin exchanges function like banks, securely holding customers' bitcoins on their behalf. Several exchanges have suffered catastrophic losses with customers permanently losing their savings. A proof of solvency demonstrates cryptographically that the exchange controls sufficient reserves to settle each customer's account. This talk will describe Provisions, a privacy-preserving proof of solvency whereby an exchange does not have to disclose its Bitcoin addresses; total holdings or liabilities; or any information about its customers. Provisions can be extended to prevent exchanges from colluding to cover for each other's losses, as well as to enable features such as proving a positive surplus or enabling fractional-reserve banking. Provisions offers practical computation times and proof sizes even for a large Bitcoin exchange with millions of customers. Joint work with Gaby Dagher, Benedikt Bünz, Jeremy Clark and Dan Boneh.
Bio: Joseph Bonneau is a Technology Fellow at the Electronic Frontier Foundation and Postdoctoral Researcher at Stanford University. In addition to researching Bitcoin and related cryptocurrencies he has worked on passwords and web authentication, secure messaging tools and HTTPS for secure web browsing. He received a PhD from the University of Cambridge under the supervision of Ross Anderson and an BS/MS from Stanford under the supervision of Dan Boneh. Last year he was as a Postdoctoral Fellow at CITP, Princeton and he has previously worked at Google, Yahoo, and Cryptography Research Inc.