o mechanisms that enable secure interaction among untrusted parties.
A core notion that underlies secure interaction between untrusted parties is a proof system. Loosely speaking, proofs enable an untrusted party to send some derivation of confidential information without giving up control completely over the information. For example, in a zero-knowledge proof, a party proves possession of a secret without leaking any of the secret bits. A hiding commitment is a proof that binds a secret to a value without leaking any secret bits, so that the secret can later be verified. There are many other proof scenarios.
Many proof techniques in cryptography were originally conceived as purely theoretical methods. Pioneering work such as Fairplay demonstrated two decades ago that end-to-end SMPC (secure multi-party computation) across a wide interconnect is within the realm of possibility, at least on a small scale. Tremendous advances have been made since then in SMPC and other methods such as probabilistically checkable proofs, zero knowledge, and oblivious RAM. Some of these advances have already brought to production methods such as zero-knowledge proofs. The exploration of practicality enhancements continues to thrive and receives additional boost from crypto-economic systems.
The first workshop of the semester, Probabilistically Checkable and Interactive Proof Systems, was co-organized by Omer Paneth, Ron Rothblum, and Justin Thaler and took place the week of September 23 to 27, 2019. The workshop was devoted to probabilistically checkable proofs, interactive proofs, zero-knowledge proofs and arguments, and their applications. Topics of interest included both the theoretical foundations of such proof systems and research efforts devoted to practical efficiency. A major goal of the workshop was to bring together researchers studying proof systems from all points on the “foundations vs. practice” spectrum.
Distributed protocols that implement coordination among parties
Distributed consensus is a core abstraction in which a set of nodes, some of which may exhibit crash or Byzantine faults, aim to reach agreement on the state of some system or a log of events. Due to the recent interest in decentralized cryptocurrencies and their applications, distributed consensus has received heightened attention from both the cryptocurrency and academic communities. From the communities’ joint efforts at deploying consensus on an Internet scale, we have achieved a new leap in our understanding of consensus. We also understand the new challenges that have come with the large-scale and decentralized nature of the deployments — challenges that were not there classically when we considered reaching consensus among three nodes on a spaceship or among a dozen nodes within a single organization.
The second workshop of the semester, Large-Scale Consensus and Blockchains, took place from October 22 to 25, 2019, and was co-organized by Dahlia Malkhi (Calibra) and Elaine Shi (Cornell University).
The workshop brought together researchers interested in distributed consensus, including representatives of the distributed systems, cryptography, and economics communities. The workshop was structured as a mix of keynotes and research presentations. It began with a day featuring four distinguished keynote talks: Barbara Liskov on the genesis of BFT consensus and on current atomic cross-chain transactions, Christian Cachin on decentralized trust models and Stellar, Maurice Herlihy on guarantees of cross-chain transactions, and Tal Rabin on managing threshold cryptography in decentralized settings. The following two days were filled with research talks by students, faculty, and industry researchers. The last day was dedicated to cross-disciplinary works on blockchain/consensus and game theory.
Mechanisms that incentivize parties to cooperate
The crypto-economic disruption goes deeper than the libertarian Bitcoin vision of digital money without government. This necessitates deep study into various societal aspects of the disruption.
Many studies cross several domai