Greetings!

This month, IC3 researchers helped deploy privacy-preserving contact tracing, proposed two ways to improve payment channels, had two papers accepted for fall conferences, and more! 
 
PRESENTATIONS
Fan Zhang presented “ Connecting Blockchains to the Real World ” at an IC3 Webinar on July 7th.

The SwissCovid App is available for download! It uses Bluetooth to share temporary identifiers, which assist in privacy-preserving contact tracing once an individual is diagnosed with COVID-19. It is the result of joint work by the Federal Office for Information Technology and Telecommunications (FOITT), the Federal Institutes of Technology in Zurich (ETH) including IC3 faculty member Srdjan Čapkun, Lausanne (EPFL), and the Swiss company Ubique. 

ACCEPTED PAPERS
Summary: The authors show how an attacker can disrupt incentives in a bitcoin-like blockchain to cause rational miners to stop mining. Their attack is cheaper than previously described BDoS attacks. 
Michael Mirkin (Technion, IC3), Yan Ji (Cornell Tech, IC3), Jonathan Pang (Cornell), Ariah Klages-Mundt (Cornell), Ittay Eyal (Technion, IC3), Ari Juels (Cornell Tech, IC3)
 
Summary: The authors present a new approach for high-throughput blockchains. They shard the node rather than the system: scaling the bandwidth, processing, and storage of the nodes, and implementing each node with multiple machines that operate together as a single node.
Alex Manuskin (Technion), Michael Mirkin (Technion), and Ittay Eyal (Technion)
 
NEW RESEARCH
Summary: The authors present Mutual-Assured-Destruction Hashed Time-Locked Contracts (MAD-HTLC), which utilizes miners to enforce honest behavior in HTLCs. If a user misbehaves, MAD-HTLC incentivizes the miners to confiscate all her funds. This makes miners the natural enforcers against bribery attacks on HTLCs with high transaction fees. 
Itay Tsabary, Matan Yechieli, Ittay Eyal (All Technion, IC3)
 
Summary: The authors offer a risk-based functional characterization of the economic structure of stablecoins. They characterize the unique risks that emerge in non-custodial stablecoins and develop a model framework that unifies existing models from economics and computer science, applying to a wide array of cryptoeconomic systems.
Ariah Klages-Mundt (Cornell), Dominik Harz (Imperial College London), Lewis Gudgeon (Imperial College London), Jun-You Liu (Cornell), Andreea Minca (Cornell)
 
Summary: The authors demonstrate the soundness of a difficulty update procedure for Nakamoto consensus when the computational power of the system is changing, assuming only that the computational power in the network does not change too fast. 
T-H. Hubert Chan (HKU), Naomi Ephraim (Cornell), Antonio Marcedone (Cornell), Andrew Morgan (Cornell), Rafael Pass (Cornell Tech), and Elaine Shi (Cornell)
 
Summary: The authors are the first to achieve expected round byzantine broadcasts even with up to 99% corrupt nodes.
Jun Wan (MIT), Hanshen Xiao (MIT), Elaine Shi (Cornell), Srinivas Devadas (MIT)
 
Summary: The authors propose a new perfectly secure OPRAM scheme with lower overhead than the field-standard for the last decade. They also propose the first perfectly secure OPRAM scheme with polylogarithmic worst-case overhead.
T-H. Hubert Chan (HKU), Wei-Kai Lin (Cornell), Kartik Nayak (Duke), and Elaine Shi (Cornell)
 
Summary: The authors provide a formal cryptographic treatment of Token-curated registries (TCRs) as well as a construction that provably hides the votes cast by individual curators. This shows a model and proof of security for a digital voting scheme. 
Elizabeth C. Crites (UCL), Mary Maller (Ethereum Foundation), Sarah Meiklejohn (UCL), Rebekah Mercer O(1) Labs
 
Summary: The authors propose Brick, the first payment channel that remains secure under network asynchrony and concurrently provides correct incentives, all with sub-second latency. It does so using a rational committee of external parties, called Wardens, who must approve the last valid state before a party can close the channel. They also propose Brick+ an off-chain construction that provides auditability on top of Brick without conflicting with its privacy guarantees.
Georgia Avarikioti (ETH Zurich), Eleftherios Kokoris Kogias (EPFL), Roger Wattenhofer (ETH Zurich), Dionysis Zindros (NKUA, IOHK)
 
Please send any new research or presentations to  sarahallen@cornell.edu  to be included in the next research update.
 
Best wishes, 
Sarah Allen
IC3 Community Manager
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