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Documents authored by Zindros, Dionysis


Document
Proofs of Proof-Of-Stake with Sublinear Complexity

Authors: Shresth Agrawal, Joachim Neu, Ertem Nusret Tas, and Dionysis Zindros

Published in: LIPIcs, Volume 282, 5th Conference on Advances in Financial Technologies (AFT 2023)


Abstract
Popular Ethereum wallets (like MetaMask) entrust centralized infrastructure providers (e.g., Infura) to run the consensus client logic on their behalf. As a result, these wallets are light-weight and high-performant, but come with security risks. A malicious provider can mislead the wallet by faking payments and balances, or censoring transactions. On the other hand, light clients, which are not in popular use today, allow decentralization, but are concretely inefficient, often with asymptotically linear bootstrapping complexity. This poses a dilemma between decentralization and performance. We design, implement, and evaluate a new proof-of-stake (PoS) superlight client with concretely efficient and asymptotically logarithmic bootstrapping complexity. Our proofs of proof-of-stake (PoPoS) take the form of a Merkle tree of PoS epochs. The verifier enrolls the provers in a bisection game, in which honest provers are destined to win once an adversarial Merkle tree is challenged at sufficient depth. We provide an implementation for mainnet Ethereum: compared to the state-of-the-art light client construction of Ethereum, our client improves time-to-completion by 9×, communication by 180×, and energy usage by 30× (when bootstrapping after 10 years of consensus execution). As an important additional application, our construction can be used to realize trustless cross-chain bridges, in which the superlight client runs within a smart contract and takes the role of an on-chain verifier. We prove our construction is secure and show how to employ it for other PoS systems such as Cardano (with fully adaptive adversary), Algorand, and Snow White.

Cite as

Shresth Agrawal, Joachim Neu, Ertem Nusret Tas, and Dionysis Zindros. Proofs of Proof-Of-Stake with Sublinear Complexity. In 5th Conference on Advances in Financial Technologies (AFT 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 282, pp. 14:1-14:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{agrawal_et_al:LIPIcs.AFT.2023.14,
  author =	{Agrawal, Shresth and Neu, Joachim and Tas, Ertem Nusret and Zindros, Dionysis},
  title =	{{Proofs of Proof-Of-Stake with Sublinear Complexity}},
  booktitle =	{5th Conference on Advances in Financial Technologies (AFT 2023)},
  pages =	{14:1--14:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-303-4},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{282},
  editor =	{Bonneau, Joseph and Weinberg, S. Matthew},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2023.14},
  URN =		{urn:nbn:de:0030-drops-192037},
  doi =		{10.4230/LIPIcs.AFT.2023.14},
  annote =	{Keywords: Proof-of-stake, blockchain, light client, superlight, bridge, Ethereum}
}
Document
Cryptocurrency Egalitarianism: A Quantitative Approach

Authors: Dimitris Karakostas, Aggelos Kiayias, Christos Nasikas, and Dionysis Zindros

Published in: OASIcs, Volume 71, International Conference on Blockchain Economics, Security and Protocols (Tokenomics 2019)


Abstract
Since the invention of Bitcoin one decade ago, numerous cryptocurrencies have sprung into existence. Among these, proof-of-work is the most common mechanism for achieving consensus, whilst a number of coins have adopted "ASIC-resistance" as a desirable property, claiming to be more "egalitarian," where egalitarianism refers to the power of each coin to participate in the creation of new coins. While proof-of-work consensus dominates the space, several new cryptocurrencies employ alternative consensus, such as proof-of-stake in which block minting opportunities are based on monetary ownership. A core criticism of proof-of-stake revolves around it being less egalitarian by making the rich richer, as opposed to proof-of-work in which everyone can contribute equally according to their computational power. In this paper, we give the first quantitative definition of a cryptocurrency’s egalitarianism. Based on our definition, we measure the egalitarianism of popular cryptocurrencies that (may or may not) employ ASIC-resistance, among them Bitcoin, Ethereum, Litecoin, and Monero. Our simulations show, as expected, that ASIC-resistance increases a cryptocurrency’s egalitarianism. We also measure the egalitarianism of a stake-based protocol, Ouroboros, and a hybrid proof-of-stake/proof-of-work cryptocurrency, Decred. We show that stake-based cryptocurrencies, under correctly selected parameters, can be perfectly egalitarian, perhaps contradicting folklore belief.

Cite as

Dimitris Karakostas, Aggelos Kiayias, Christos Nasikas, and Dionysis Zindros. Cryptocurrency Egalitarianism: A Quantitative Approach. In International Conference on Blockchain Economics, Security and Protocols (Tokenomics 2019). Open Access Series in Informatics (OASIcs), Volume 71, pp. 7:1-7:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{karakostas_et_al:OASIcs.Tokenomics.2019.7,
  author =	{Karakostas, Dimitris and Kiayias, Aggelos and Nasikas, Christos and Zindros, Dionysis},
  title =	{{Cryptocurrency Egalitarianism: A Quantitative Approach}},
  booktitle =	{International Conference on Blockchain Economics, Security and Protocols (Tokenomics 2019)},
  pages =	{7:1--7:21},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-108-5},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{71},
  editor =	{Danos, Vincent and Herlihy, Maurice and Potop-Butucaru, Maria and Prat, Julien and Tucci-Piergiovanni, Sara},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.Tokenomics.2019.7},
  URN =		{urn:nbn:de:0030-drops-119715},
  doi =		{10.4230/OASIcs.Tokenomics.2019.7},
  annote =	{Keywords: blockchain, egalitarianism, cryptocurrency, economics, proof-of-work, proof-of-stake}
}
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