Volume

OASIcs, Volume 92

4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)



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Event

FAB 2021, May 7, 2021, University of California, Davis, California, USA (Virtual Conference)

Editors

Vincent Gramoli
  • University of Sydney and EPFL, Lausanne, Switzerland
Mohammad Sadoghi
  • University of California, Davis, USA

Publication Details

  • published at: 2021-06-25
  • Publisher: Schloss-Dagstuhl - Leibniz Zentrum für Informatik
  • ISBN: 978-3-95977-196-2
  • DBLP: db/conf/fab/fab2021

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Documents

No documents found matching your filter selection.
Document
Complete Volume
OASIcs, Volume 92, FAB 2021, Complete Volume

Authors: Vincent Gramoli and Mohammad Sadoghi


Abstract
OASIcs, Volume 92, FAB 2021, Complete Volume

Cite as

Vincent Gramoli and Mohammad Sadoghi. OASIcs, Volume 92, FAB 2021, Complete Volume. In 4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021). Open Access Series in Informatics (OASIcs), Volume 92, pp. 1-96, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@Proceedings{gramoli_et_al:OASIcs.FAB.2021,
  title =	{{OASIcs, Volume 92, FAB 2021, Complete Volume}},
  booktitle =	{4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)},
  pages =	{1--96},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-196-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{92},
  editor =	{Gramoli, Vincent and Sadoghi, Mohammad},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FAB.2021},
  URN =		{urn:nbn:de:0030-drops-139857},
  doi =		{10.4230/OASIcs.FAB.2021},
  annote =	{Keywords: OASIcs, Volume 92, FAB 2021, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Vincent Gramoli and Mohammad Sadoghi


Abstract
Front Matter, Table of Contents, Preface, Conference Organization

Cite as

Vincent Gramoli and Mohammad Sadoghi. Front Matter, Table of Contents, Preface, Conference Organization. In 4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021). Open Access Series in Informatics (OASIcs), Volume 92, pp. 0:i-0:viii, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{gramoli_et_al:OASIcs.FAB.2021.0,
  author =	{Gramoli, Vincent and Sadoghi, Mohammad},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)},
  pages =	{0:i--0:viii},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-196-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{92},
  editor =	{Gramoli, Vincent and Sadoghi, Mohammad},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FAB.2021.0},
  URN =		{urn:nbn:de:0030-drops-139865},
  doi =		{10.4230/OASIcs.FAB.2021.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Tenderbake - A Solution to Dynamic Repeated Consensus for Blockchains

Authors: Lăcrămioara Aştefănoaei, Pierre Chambart, Antonella Del Pozzo, Thibault Rieutord, Sara Tucci-Piergiovanni, and Eugen Zălinescu


Abstract
First-generation blockchains provide probabilistic finality: a block can be revoked, albeit the probability decreases as the block "sinks" deeper into the chain. Recent proposals revisited committee-based BFT consensus to provide deterministic finality: as soon as a block is validated, it is never revoked. A distinguishing characteristic of these second-generation blockchains over classical BFT protocols is that committees change over time as the participation and the blockchain state evolve. In this paper, we push forward in this direction by proposing a formalization of the Dynamic Repeated Consensus problem and by providing generic procedures to solve it in the context of blockchains. Our approach is modular in that one can plug in different synchronizers and single-shot consensus. To offer a complete solution, we provide a concrete instantiation, called {{Tenderbake}}, and present a blockchain synchronizer and a single-shot consensus algorithm, working in a Byzantine and partially synchronous system model with eventually synchronous clocks. In contrast to recent proposals, our methodology is driven by the need to bound the message buffers. This is essential in preventing spamming and run-time memory errors. Moreover, {{Tenderbake}} processes can synchronize with each other without exchanging messages, leveraging instead the information stored in the blockchain.

Cite as

Lăcrămioara Aştefănoaei, Pierre Chambart, Antonella Del Pozzo, Thibault Rieutord, Sara Tucci-Piergiovanni, and Eugen Zălinescu. Tenderbake - A Solution to Dynamic Repeated Consensus for Blockchains. In 4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021). Open Access Series in Informatics (OASIcs), Volume 92, pp. 1:1-1:23, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{astefanoaei_et_al:OASIcs.FAB.2021.1,
  author =	{A\c{s}tef\u{a}noaei, L\u{a}cr\u{a}mioara and Chambart, Pierre and Del Pozzo, Antonella and Rieutord, Thibault and Tucci-Piergiovanni, Sara and Z\u{a}linescu, Eugen},
  title =	{{Tenderbake - A Solution to Dynamic Repeated Consensus for Blockchains}},
  booktitle =	{4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)},
  pages =	{1:1--1:23},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-196-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{92},
  editor =	{Gramoli, Vincent and Sadoghi, Mohammad},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FAB.2021.1},
  URN =		{urn:nbn:de:0030-drops-139877},
  doi =		{10.4230/OASIcs.FAB.2021.1},
  annote =	{Keywords: Blockchain, BFT-Consensus, Dynamic Repeated Consensus}
}
Document
Byzantine-Tolerant Distributed Grow-Only Sets: Specification and Applications

Authors: Vicent Cholvi, Antonio Fernández Anta, Chryssis Georgiou, Nicolas Nicolaou, Michel Raynal, and Antonio Russo


Abstract
In order to formalize Distributed Ledger Technologies and their interconnections, a recent line of research work has formulated the notion of Distributed Ledger Object (DLO), which is a concurrent object that maintains a totally ordered sequence of records, abstracting blockchains and distributed ledgers. Through DLO, the Atomic Appends problem, intended as the need of a primitive able to append multiple records to distinct ledgers in an atomic way, is studied as a basic interconnection problem among ledgers. In this work, we propose the Distributed Grow-only Set object (DSO), which instead of maintaining a sequence of records, as in a DLO, maintains a set of records in an immutable way: only Add and Get operations are provided. This object is inspired by the Grow-only Set (G-Set) data type which is part of the Conflict-free Replicated Data Types. We formally specify the object and we provide a consensus-free Byzantine-tolerant implementation that guarantees eventual consistency. We then use our Byzantine-tolerant DSO (BDSO) implementation to provide consensus-free algorithmic solutions to the Atomic Appends and Atomic Adds (the analogous problem of atomic appends applied on G-Sets) problems, as well as to construct consensus-free Single-Writer BDLOs. We believe that the BDSO has applications beyond the above-mentioned problems.

Cite as

Vicent Cholvi, Antonio Fernández Anta, Chryssis Georgiou, Nicolas Nicolaou, Michel Raynal, and Antonio Russo. Byzantine-Tolerant Distributed Grow-Only Sets: Specification and Applications. In 4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021). Open Access Series in Informatics (OASIcs), Volume 92, pp. 2:1-2:19, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{cholvi_et_al:OASIcs.FAB.2021.2,
  author =	{Cholvi, Vicent and Fern\'{a}ndez Anta, Antonio and Georgiou, Chryssis and Nicolaou, Nicolas and Raynal, Michel and Russo, Antonio},
  title =	{{Byzantine-Tolerant Distributed Grow-Only Sets: Specification and Applications}},
  booktitle =	{4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)},
  pages =	{2:1--2:19},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-196-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{92},
  editor =	{Gramoli, Vincent and Sadoghi, Mohammad},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FAB.2021.2},
  URN =		{urn:nbn:de:0030-drops-139883},
  doi =		{10.4230/OASIcs.FAB.2021.2},
  annote =	{Keywords: Grow-only Sets, Distributed Ledgers, Blockchains, Atomic appends}
}
Document
DAISIM: A Computational Simulator for the MakerDAO Stablecoin

Authors: Shreyas Bhat, Ayten Betul Kahya, Bhaskar Krishnamachari, and Rohit Kumar


Abstract
We present a computational simulation of the single-collateral DAI stablecoin launched by the MakerDAO project in 2017. At the core of the simulation is a model of cryptocurrency investors acting as rational Markowitz mean-variance portfolio optimizers, with heterogeneous risk tolerance. The simulator, called DAISIM, incorporates automated order matching and price update mechanisms to determine the DAI price. We use the simulator to evaluate how the single-collateral DAI price, as well as portfolio allocations, vary for a given population of investors as a function of exogenous parameters such as the price of ETH and various system parameters including stability rate and transaction fee. DAISIM is being made available as open-source and may be useful in evaluating other similar projects.

Cite as

Shreyas Bhat, Ayten Betul Kahya, Bhaskar Krishnamachari, and Rohit Kumar. DAISIM: A Computational Simulator for the MakerDAO Stablecoin. In 4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021). Open Access Series in Informatics (OASIcs), Volume 92, pp. 3:1-3:13, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{bhat_et_al:OASIcs.FAB.2021.3,
  author =	{Bhat, Shreyas and Kahya, Ayten Betul and Krishnamachari, Bhaskar and Kumar, Rohit},
  title =	{{DAISIM: A Computational Simulator for the MakerDAO Stablecoin}},
  booktitle =	{4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)},
  pages =	{3:1--3:13},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-196-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{92},
  editor =	{Gramoli, Vincent and Sadoghi, Mohammad},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FAB.2021.3},
  URN =		{urn:nbn:de:0030-drops-139899},
  doi =		{10.4230/OASIcs.FAB.2021.3},
  annote =	{Keywords: Stablecoin, Simulator, MakerDAO}
}
Document
TimeFabric: Trusted Time for Permissioned Blockchains

Authors: Aritra Mitra, Christian Gorenflo, Lukasz Golab, and S. Keshav


Abstract
As the popularity of blockchains continues to rise, blockchain platforms must be enhanced to support new application needs. In this paper, we propose one such enhancement that is essential for financial applications and online marketplaces - support for time-based logic such as verifying deadlines or expiry dates and examining a time window of recent account activity. We present a lightweight solution to reach consensus on the current time without relying on external time oracles. Our solution assigns timestamps to blocks at transaction validation time and maintains a cache reflecting the effects of recent transactions. We implement a proof-of-concept prototype, called TimeFabric, in Hyperledger Fabric, a popular permissioned blockchain platform, and experimentally demonstrate high throughput and minimal overhead (approximately 3%) of maintaining trusted time. We also demonstrate a 2x performance improvement due to the cache, compared to reconstructing account histories from the ledger.

Cite as

Aritra Mitra, Christian Gorenflo, Lukasz Golab, and S. Keshav. TimeFabric: Trusted Time for Permissioned Blockchains. In 4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021). Open Access Series in Informatics (OASIcs), Volume 92, pp. 4:1-4:15, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{mitra_et_al:OASIcs.FAB.2021.4,
  author =	{Mitra, Aritra and Gorenflo, Christian and Golab, Lukasz and Keshav, S.},
  title =	{{TimeFabric: Trusted Time for Permissioned Blockchains}},
  booktitle =	{4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)},
  pages =	{4:1--4:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-196-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{92},
  editor =	{Gramoli, Vincent and Sadoghi, Mohammad},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FAB.2021.4},
  URN =		{urn:nbn:de:0030-drops-139906},
  doi =		{10.4230/OASIcs.FAB.2021.4},
  annote =	{Keywords: Permissioned Blockchain, Timestamp, Clock, Sliding Window, Hyerpleger Fabric}
}
Document
Dynamic Curves for Decentralized Autonomous Cryptocurrency Exchanges

Authors: Bhaskar Krishnamachari, Qi Feng, and Eugenio Grippo


Abstract
One of the exciting recent developments in decentralized finance (DeFi) has been the development of decentralized cryptocurrency exchanges that can autonomously handle conversion between different cryptocurrencies. Decentralized exchange protocols such as Uniswap, Curve and other types of Automated Market Makers (AMMs) maintain a liquidity pool (LP) of two or more assets constrained to maintain at all times a mathematical relation to each other, defined by a given function or curve. Examples of such functions are the constant-sum and constant-product AMMs. Existing systems however suffer from several challenges. They require external arbitrageurs to restore the price of tokens in the pool to match the market price. Such activities can potentially drain resources from the liquidity pool. In particular dramatic market price changes can result in low liquidity with respect to one or more of the assets and reduce the total value of the LP. We propose in this work a new approach to constructing the AMM by proposing the idea of dynamic curves. It utilizes input from a market price oracle to modify the mathematical relationship between the assets so that the pool price continuously and automatically adjusts to be identical to the market price. This approach eliminates arbitrage opportunities and, as we show through simulations, maintains liquidity in the LP for all assets and the total value of the LP over a wide range of market prices.

Cite as

Bhaskar Krishnamachari, Qi Feng, and Eugenio Grippo. Dynamic Curves for Decentralized Autonomous Cryptocurrency Exchanges. In 4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021). Open Access Series in Informatics (OASIcs), Volume 92, pp. 5:1-5:14, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2021)


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@InProceedings{krishnamachari_et_al:OASIcs.FAB.2021.5,
  author =	{Krishnamachari, Bhaskar and Feng, Qi and Grippo, Eugenio},
  title =	{{Dynamic Curves for Decentralized Autonomous Cryptocurrency Exchanges}},
  booktitle =	{4th International Symposium on Foundations and Applications of Blockchain 2021 (FAB 2021)},
  pages =	{5:1--5:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-196-2},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{92},
  editor =	{Gramoli, Vincent and Sadoghi, Mohammad},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.FAB.2021.5},
  URN =		{urn:nbn:de:0030-drops-139911},
  doi =		{10.4230/OASIcs.FAB.2021.5},
  annote =	{Keywords: Decentralized Exchange, Automated Market Maker, Decentralized Finance, Dynamic Curves}
}

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