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Sarah Azouvi

Research Scientist / ConsensusLab

Education

PhD in Computer Science, 2021

University College London

Sarah is a research scientist with interests that lie at the intersection of Applied Cryptography, Distributed Systems, and Game Theory. During her PhD, she mostly worked on decentralized consensus protocols but also looked at other aspects of decentralized systems such as their governance.

Areas of Expertise

Blockchain, Consensus

Publications

2022-12-13 / Conference paper
Pikachu: Securing PoS blockchains from long-range attacks by checkpointing into Bitcoin PoW using Taproot
Blockchain systems based on a reusable resource, such as proof-of-stake (PoS), provide weaker security guarantees than those based on proof-of-work. Specifically, they are vulnerable to long-range attacks, where an adversary can corrupt prior participants in order to rewrite the full history of the chain.
ConsensusDay 22 / 2022.11.07 / Los Angeles, CA, USA
2022-01-26 / Conference paper
Decentralisation conscious players and system reliability
We propose a game-theoretic model of the reliability of de- centralised systems based on Varian’s model of system reliability [27], to which we add a new normalized total effort case that models decentrali- sation conscious players that prioritize decentralisation.
Financial Cryptography and Data Security 2022 / 2022.05.02 / St. George's, Grenada
Sarah Azouvi , Alexander Hicks
2022-01-24 / Conference paper
Sliding window challenge process for congestion detection
Many prominent smart contract applications such as payment channels, auctions, and voting systems often involve a mechanism in which some party must respond to a challenge or appeal some action within a fixed time limit.
Financial Cryptography and Data Security 2022 / 2022.05.02 / St. George’s, Grenada
Ayelet Lotem, Sarah Azouvi , Aviv Zohar, Patrick McCorry
2021-11-16 / Conference paper
Private attacks in longest chain proof-of-stake protocols with single secret leader elections
Single Secret Leader Elections have recently been proposed as an improved leader election mechanism for proof-of-stake (PoS) blockchains. However, the security gain they provide has not been quantified. In this work, we present a comparison of PoS longest-chain protocols that are based on Single Secret Leader Elections (SSLE) - that elect exactly one leader per round - versus those based on Probabilistic Leader Elections (PLE) - where one leader is elected on expectation.
AFT '21: 3rd ACM Conference on Advances in Financial Technologies / 2021.09.28
Sarah Azouvi , Daniele Cappelletti
2020-10-21 / Conference paper
Winkle: foiling long-range attacks in proof-of-stake systems
Winkle protects any validator-based byzantine fault tolerant consensus mechanisms, such as those used in modern Proof-of-Stake blockchains, against long-range attacks where old validators’ signature keys get compromised. Winkle is a decentralized secondary layer of client-based validation, where a client includes a single additional field into a transaction that they sign: a hash of the previously sequenced block.
AFT '20: 2nd ACM Conference on Advances in Financial Technologies / 2020.10.21 / New York, NY, USA
Sarah Azouvi , George Danezis, Valeria Nikolaenko
2020-03-03 / Conference paper
SoK: Tools for game theoretic models of security for cryptocurrencies
Cryptocurrencies have garnered much attention in recent years, both from the academic community and industry. One interesting aspect of cryptocurrencies is their explicit consideration of incentives at the protocol level, which has motivated a large body of work, yet many open problems still exist and current systems rarely deal with incentive related problems well.
Cryptoeconomic Systems / 2020.03.07 / Cambridge, MA, USA
Sarah Azouvi , Alexander Hicks

Blog posts

2022-04-20 / Blog
The first graduating class of ConsensusLab projects
When ConsensusLab launched last year, we published a roadmap covering our first 18 months. We are still working towards that same roadmap, with minor adjustments over time to accommodate the changing landscape and externalities.
2021-07-30 / News
ConsensusLab: supercharging our consensus research
We are excited to announce the launch of ConsensusLab, a new research group focused on scalable consensus for decentralised systems and a part of Protocol Labs Research. Consensus — loosely defined as global agreement on the state of a decentralised network across its mutually untrusting participants — has been known to be at the heart of decentralised systems ever since the inception of Nakamoto’s Proof-of-Work (PoW) consensus.