4 Search Results for "Lizurej, Tomasz"

Document
DOI: 10.4230/LIPIcs.DISC.2025.23
Boosting Payment Channel Network Liquidity with Topology Optimization and Transaction Selection

Authors: Krishnendu Chatterjee, Jan Matyáš Křišťan, Stefan Schmid, Jakub Svoboda, and Michelle Yeo

Published in: LIPIcs, Volume 356, 39th International Symposium on Distributed Computing (DISC 2025)

Abstract
Payment channel networks (PCNs) are a promising technology that alleviates blockchain scalability by shifting the transaction load from the blockchain to the PCN. Nevertheless, the network topology has to be carefully designed to maximise the transaction throughput in PCNs. Additionally, users in PCNs also have to make optimal decisions on which transactions to forward and which to reject to prolong the lifetime of their channels. In this work, we consider an input sequence of transactions over p parties. Each transaction consists of a transaction size, source, and target, and can be either accepted or rejected (entailing a cost). The goal is to design a PCN topology among the p cooperating parties, along with the channel capacities, and then output a decision for each transaction in the sequence to minimise the cost of creating and augmenting channels, as well as the cost of rejecting transactions. Our main contribution is an 𝒪(p) approximation algorithm for the problem with p parties. We further show that with some assumptions on the distribution of transactions, we can reduce the approximation ratio to 𝒪(√p). We complement our theoretical analysis with an empirical study of our assumptions and approach in the context of the Lightning Network.
Cite as

Krishnendu Chatterjee, Jan Matyáš Křišťan, Stefan Schmid, Jakub Svoboda, and Michelle Yeo. Boosting Payment Channel Network Liquidity with Topology Optimization and Transaction Selection. In 39th International Symposium on Distributed Computing (DISC 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 356, pp. 23:1-23:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{chatterjee_et_al:LIPIcs.DISC.2025.23,
  author =	{Chatterjee, Krishnendu and K\v{r}i\v{s}\v{t}an, Jan Maty\'{a}\v{s} and Schmid, Stefan and Svoboda, Jakub and Yeo, Michelle},
  title =	{{Boosting Payment Channel Network Liquidity with Topology Optimization and Transaction Selection}},
  booktitle =	{39th International Symposium on Distributed Computing (DISC 2025)},
  pages =	{23:1--23:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-402-4},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{356},
  editor =	{Kowalski, Dariusz R.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2025.23},
  URN =		{urn:nbn:de:0030-drops-248402},
  doi =		{10.4230/LIPIcs.DISC.2025.23},
  annote =	{Keywords: Blockchains, Cryptocurrencies, Payment Channel Networks, Throughput, Optimisation, Graph Algorithms, Approximation Algorithms}
}
Document
DOI: 10.4230/LIPIcs.ITCS.2025.90
Polynomial Size, Short-Circuit Resilient Circuits for NC

Authors: Yael Tauman Kalai and Raghuvansh R. Saxena

Published in: LIPIcs, Volume 325, 16th Innovations in Theoretical Computer Science Conference (ITCS 2025)

Abstract
We show how to convert any circuit of poly-logarithmic depth and polynomial size into a functionally equivalent circuit of polynomial size (and polynomial depth) that is resilient to adversarial short-circuit errors. Specifically, the resulting circuit computes the same function even if up to ε d gates on every root-to-leaf path are short-circuited, i.e., their output is replaced with the value of one of its inputs, where d is the depth of the circuit and ε > 0 is a fixed constant. Previously, such a result was known for formulas (Kalai-Lewko-Rao, FOCS 2012). It was also known how to convert general circuits to error resilient ones whose size is quasi-polynomial in the size of the original circuit (Efremenko et al. STOC 2022). The reason both these works do not extend to our setting is that there may be many paths from the root to a given gate, and the resilient circuits needs to "remember" a lot of information about these paths, which causes it to be large. Our main idea is to reduce the amount of this information at the cost of increasing the depth of the resilient circuit.
Cite as

Yael Tauman Kalai and Raghuvansh R. Saxena. Polynomial Size, Short-Circuit Resilient Circuits for NC. In 16th Innovations in Theoretical Computer Science Conference (ITCS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 325, pp. 90:1-90:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{taumankalai_et_al:LIPIcs.ITCS.2025.90,
  author =	{Tauman Kalai, Yael and Saxena, Raghuvansh R.},
  title =	{{Polynomial Size, Short-Circuit Resilient Circuits for NC}},
  booktitle =	{16th Innovations in Theoretical Computer Science Conference (ITCS 2025)},
  pages =	{90:1--90:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-361-4},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{325},
  editor =	{Meka, Raghu},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2025.90},
  URN =		{urn:nbn:de:0030-drops-227181},
  doi =		{10.4230/LIPIcs.ITCS.2025.90},
  annote =	{Keywords: Error-resilient computation, short-circuit errors}
}
Document
DOI: 10.4230/LIPIcs.AFT.2024.11
Bribe & Fork: Cheap PCN Bribing Attacks via Forking Threat

Authors: Zeta Avarikioti, Paweł Kędzior, Tomasz Lizurej, and Tomasz Michalak

Published in: LIPIcs, Volume 316, 6th Conference on Advances in Financial Technologies (AFT 2024)

Abstract
In this work, we reexamine the vulnerability of Payment Channel Networks (PCNs) to bribing attacks, where an adversary incentivizes blockchain miners to deliberately ignore a specific transaction to undermine the punishment mechanism of PCNs. While previous studies have posited a prohibitive cost for such attacks, we show that this cost can be dramatically reduced (to approximately $125), thereby increasing the likelihood of these attacks. To this end, we introduce Bribe & Fork, a modified bribing attack that leverages the threat of a so-called feather fork which we analyze with a novel formal model for the mining game with forking. We empirically analyze historical data of some real-world blockchain implementations to evaluate the scale of this cost reduction. Our findings shed more light on the potential vulnerability of PCNs and highlight the need for robust solutions.
Cite as

Zeta Avarikioti, Paweł Kędzior, Tomasz Lizurej, and Tomasz Michalak. Bribe & Fork: Cheap PCN Bribing Attacks via Forking Threat. In 6th Conference on Advances in Financial Technologies (AFT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 316, pp. 11:1-11:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{avarikioti_et_al:LIPIcs.AFT.2024.11,
  author =	{Avarikioti, Zeta and K\k{e}dzior, Pawe{\l} and Lizurej, Tomasz and Michalak, Tomasz},
  title =	{{Bribe \& Fork: Cheap PCN Bribing Attacks via Forking Threat}},
  booktitle =	{6th Conference on Advances in Financial Technologies (AFT 2024)},
  pages =	{11:1--11:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-345-4},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{316},
  editor =	{B\"{o}hme, Rainer and Kiffer, Lucianna},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2024.11},
  URN =		{urn:nbn:de:0030-drops-209473},
  doi =		{10.4230/LIPIcs.AFT.2024.11},
  annote =	{Keywords: Blockchain, Payment Channels Networks, Timelock Bribing, Feather Forking}
}
Document
DOI: 10.4230/LIPIcs.ITCS.2023.10
Efficiently Testable Circuits

Authors: Mirza Ahad Baig, Suvradip Chakraborty, Stefan Dziembowski, Małgorzata Gałązka, Tomasz Lizurej, and Krzysztof Pietrzak

Published in: LIPIcs, Volume 251, 14th Innovations in Theoretical Computer Science Conference (ITCS 2023)

Abstract
In this work, we put forward the notion of "efficiently testable circuits" and provide circuit compilers that transform any circuit into an efficiently testable one. Informally, a circuit is testable if one can detect tampering with the circuit by evaluating it on a small number of inputs from some test set. Our technical contribution is a compiler that transforms any circuit C into a testable circuit (Ĉ,𝕋̂) for which we can detect arbitrary tampering with all wires in Ĉ. The notion of a testable circuit is weaker or incomparable to existing notions of tamper-resilience, which aim to detect or even correct for errors introduced by tampering during every query, but our new notion is interesting in several settings, and we achieve security against much more general tampering classes - like tampering with all wires - with very modest overhead. Concretely, starting from a circuit C of size n and depth d, for any L (think of L as a small constant, say L = 4), we get a testable (Ĉ,𝕋̂) where Ĉ is of size ≈ 12n and depth d+log(n)+L⋅ n^{1/L}. The test set 𝕋̂ is of size 4⋅ 2^L. The number of extra input and output wires (i.e., pins) we need to add for the testing is 3+L and 2^L, respectively.
Cite as

Mirza Ahad Baig, Suvradip Chakraborty, Stefan Dziembowski, Małgorzata Gałązka, Tomasz Lizurej, and Krzysztof Pietrzak. Efficiently Testable Circuits. In 14th Innovations in Theoretical Computer Science Conference (ITCS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 251, pp. 10:1-10:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{baig_et_al:LIPIcs.ITCS.2023.10,
  author =	{Baig, Mirza Ahad and Chakraborty, Suvradip and Dziembowski, Stefan and Ga{\l}\k{a}zka, Ma{\l}gorzata and Lizurej, Tomasz and Pietrzak, Krzysztof},
  title =	{{Efficiently Testable Circuits}},
  booktitle =	{14th Innovations in Theoretical Computer Science Conference (ITCS 2023)},
  pages =	{10:1--10:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-263-1},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{251},
  editor =	{Tauman Kalai, Yael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2023.10},
  URN =		{urn:nbn:de:0030-drops-175130},
  doi =		{10.4230/LIPIcs.ITCS.2023.10},
  annote =	{Keywords: circuit compilers, circuit integrity, circuit testing}
}
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