11 papers
Censorship-Resistant Sealed-Bid Auctions on Blockchains
Orestis Alpos, Lioba Heimbach, Kartik Nayak +1
Auctions are now central to blockchain markets, settling NFT sales, token launches, DeFi liquidations, and arbitrage opportunities. Each on-chain bid is a public transaction whose…
Monotone Erasure Codes
Vivien Bammert, Annalisa Cimatti, Orestis Alpos +2
Erasure codes are a critical component in reliable storage systems today, and many blockchain systems use consensus protocols that involve erasure codes to reduce their communicati…
Bitcoin-IPC: Scaling Bitcoin with a Network of Proof-of-Stake Subnets
Marko Vukolić, Orestis Alpos, Jakov Mitrovski +3
Despite holding over $1.7T in value, Bitcoin scales poorly: Layer-1 (L1) processes only a few transactions per second, and Layer-2 (L2) solutions suffer from operational and liquid…
Formalization and security analysis of the Bridgeless protocol
Orestis Alpos, Oleg Fomenko, Dimitris Karakostas +2
This paper formalizes the proves the security of the Bridgeless protocol, a protocol able to bridge tokens between various chains. The Bridgeless protocol is run by a set of valida…
An overview of the efficiency and censorship-resistance guarantees of widely-used consensus protocols
Orestis Alpos, Bernardo David, Nikolas Kamarinakis +1
Censorship resistance with short-term inclusion guarantees is an important feature of decentralized systems, missing from many state-of-the-art and even deployed consensus protocol…
Thetacrypt: A Distributed Service for Threshold Cryptography
Mariarosaria Barbaraci, Noah Schmid, Orestis Alpos +2
Threshold cryptography is a powerful and well-known technique with many applications to systems relying on distributed trust. It has recently emerged also as a solution to challeng…
Pod: An Optimal-Latency, Censorship-Free, and Accountable Generalized Consensus Layer
Orestis Alpos, Bernardo David, Jakov Mitrovski +2
This work addresses the inherent issues of high latency in blockchains and low scalability in traditional consensus protocols. We present pod, a novel notion of consensus whose fir…
Eating sandwiches: Modular and lightweight elimination of transaction reordering attacks
Orestis Alpos, Ignacio Amores-Sesar, Christian Cachin +1
Traditional blockchains grant the miner of a block full control not only over which transactions but also their order. This constitutes a major flaw discovered with the introductio…
How to Trust Strangers: Composition of Byzantine Quorum Systems
Orestis Alpos, Christian Cachin, Luca Zanolini
Trust is the basis of any distributed, fault-tolerant, or secure system. A trust assumption specifies the failures that a system, such as a blockchain network, can tolerate and det…
On the Synchronization Power of Token Smart Contracts
Orestis Alpos, Christian Cachin, Giorgia Azzurra Marson +1
Modern blockchains support a variety of distributed applications beyond cryptocurrencies, including smart contracts -- which let users execute arbitrary code in a distributed and d…
Consensus Beyond Thresholds: Generalized Byzantine Quorums Made Live
Orestis Alpos, Christian Cachin
Existing Byzantine fault-tolerant (BFT) consensus protocols address only threshold failures, where the participating nodes fail independently of each other, each one fails equally…