License: Creative Commons Attribution 3.0 Unported license (CC BY 3.0)
When quoting this document, please refer to the following
DOI: 10.4230/OASIcs.Tokenomics.2019.8
URN: urn:nbn:de:0030-drops-119725
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Bramas, Quentin

The Stability and the Security of the Tangle

OASIcs-Tokenomics-2019-8.pdf (0.5 MB)


In this paper we study the stability and the security of the distributed data structure at the base of the IOTA protocol, called the Tangle. The contribution of this paper is twofold. First, we present a simple model to analyze the Tangle and give the first discrete time formal analyzes of the average number of unconfirmed transactions and the average confirmation time of a transaction.
Then, we define the notion of assiduous honest majority that captures the fact that the honest nodes have more hashing power than the adversarial nodes and that all this hashing power is constantly used to create transactions. This notion is important because we prove that it is a necessary assumption to protect the Tangle against double-spending attacks, and this is true for any tip selection algorithm (which is a fundamental building block of the protocol) that verifies some reasonable assumptions. In particular, the same is true with the Markov Chain Monte Carlo selection tip algorithm currently used in the IOTA protocol.
Our work shows that either all the honest nodes must constantly use all their hashing power to validate the main chain (similarly to the Bitcoin protocol) or some kind of authority must be provided to avoid this kind of attack (like in the current version of the IOTA where a coordinator is used).
The work presented here constitute a theoretical analysis and cannot be used to attack the current IOTA implementation. The goal of this paper is to present a formalization of the protocol and, as a starting point, to prove that some assumptions are necessary in order to defend the system again double-spending attacks. We hope that it will be used to improve the current protocol with a more formal approach.

BibTeX - Entry

  author =	{Quentin Bramas},
  title =	{{The Stability and the Security of the Tangle}},
  booktitle =	{International Conference on Blockchain Economics, Security and Protocols (Tokenomics 2019)},
  pages =	{8:1--8:15},
  series =	{OpenAccess Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-108-5},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{71},
  editor =	{Vincent Danos and Maurice Herlihy and Maria Potop-Butucaru and Julien Prat and Sara Tucci-Piergiovanni},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-119725},
  doi =		{10.4230/OASIcs.Tokenomics.2019.8},
  annote =	{Keywords: Distributed Ledger Technology, Security, Stability}

Keywords: Distributed Ledger Technology, Security, Stability
Collection: International Conference on Blockchain Economics, Security and Protocols (Tokenomics 2019)
Issue Date: 2020
Date of publication: 17.03.2020

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