Hacking, Distributed

Attacking the DeFi Ecosystem with Flash Loans for Fun and Profit

defi blockchain security attacks flash loans March 11, 2020 at 02:00 PM Kaihua Qin, Liyi Zhou, Benjamin Livshits, and Arthur Gervais

Flash loans are a recent blockchain smart contract construct that enable the issuance of loans that are only valid within one transaction and must be repaid by the end of that transaction. This post examines recent flash loan attacks on DeFi, and outlines how they could have been far more effective, boosting attack profitability to 829K USD (instead of 350K USD) and 1.1M USD (instead of 600K USD), respectively.

Libra: Succinct Zero-Knowledge Proofs with Optimal Prover Computation

zero knowledge zkp blockchain decentralization February 12, 2020 at 10:00 AM Tiancheng Xie, Jiaheng Zhang, Yupeng Zhang, Charalampos Papamanthou, and Dawn Song

Libra is a zero-knowledge proof protocol that achieves extremely fast prover time and succinct proof size and verification time. Not only does it have good complexity in terms of asymptotics, but also its actual running time is well within the bounds of enabling realistic applications. It can be applied in areas such as blockchain technology and privacy-preserving smart contracts. It is currently being implemented by Oasis Labs. This blog post is based on a paper authored by Tiancheng Xie, Jiaheng Zhang, Yupeng Zhang, Charalampos Papamanthou and Dawn Song.

Liberating web data using DECO, a privacy-preserving oracle protocol

oracle blockchain decentralization September 03, 2019 at 02:00 PM Fan Zhang, Steven Goldfeder, and Ari Juels

An oracle is a service that provides data to smart contracts or other systems. Oracles obtain their data from trusted websites. But even those that relay data correctly cannot safely access users' web-session data, because they can't enforce privacy. DECO is a privacy-preserving oracle protocol. Using cryptographic techniques, it lets users prove facts about their web (TLS) sessions to oracles while hiding privacy-sensitive data. DECO can make private and public web data accessible to a rich spectrum of applications, for blockchains and traditional (non-blockchain) systems.

Ostraka: Blockchain Scaling by Node Sharding

scaling sharding May 27, 2019 at 10:00 AM Alex Manuskin and Ittay Eyal

Ostraka is a node blockchain node architecture, with scale-out properties.

On Stablecoins and Beauty Pageants

stablecoins ethereum May 07, 2019 at 09:30 AM Amani Moin and Kevin Sekniqi

Some algorithmic stablecoins have proposed incorporating price feeds by asking their token holders. In this post, we point out that this mechanism is broken because of a fundamental incentive misalignment.

Decentralize Your Secrets with CHURP

secret sharing key loss decentralization April 05, 2019 at 09:00 AM Deepak Maram, Fan Zhang, and Ari Juels

Achieving true decentralization requires decentralized cryptography. CHURP is a cryptographic protocol for secret sharing in decentralized settings. In such a setting where nodes may come and go, traditional secret sharing (e.g., Shamir's) is no longer secure. Featuring several fundamental innovations, CHURP accomplishes the mission while being 2300x more efficient than previous schemes!