Unstable throughput: when the difficulty algorithm breaks
File(s)ilie-werner-stewart-knottenbelt-icbc-2021.pdf (886.16 KB)
Accepted version
Author(s)
Ilie, Dragos
Werner, Sam
Stewart, iain
Knottenbelt, William
Type
Conference Paper
Abstract
In Proof-of-Work blockchains, difficulty algorithms serve the crucial purpose of maintaining a stable transaction throughput by dynamically adjusting the block difficulty in response to the miners’ constantly changing computational power. Blockchains that may experience severe hash rate fluctuations need difficulty algorithms that quickly adapt the mining difficulty. However, without careful design, the system could be gamed by miners using coin-hopping strategies to manipulate the block difficulty for profit. Such miner behavior results in an unreliable system due to the unstable processing of transactions. We provide an empirical analysis of how Bitcoin Cash’s difficulty algorithm design leads to cyclicality in block solve times as a consequence of a positive feedback loop. In response, we mathematically derive a difficulty algorithm using a negative exponential filter which prohibits the formation of positive feedback and exhibits additional desirable properties, such as history agnosticism. We compare the described algorithm to that of Bitcoin Cash in a simulated mining environment and verify that the former would eliminate the severe oscillations in transaction throughput.
Date Issued
2021-06-24
Date Acceptance
2021-02-18
Citation
2021 IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2021), 2021, pp.1-5
Publisher
IEEE
Start Page
1
End Page
5
Journal / Book Title
2021 IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2021)
Copyright Statement
© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
Source
2021 IEEE Conference on Blockchain and Cryptocurrency (ICBC 2021)
Subjects
Science & Technology
Technology
Computer Science, Information Systems
Computer Science, Interdisciplinary Applications
Computer Science
Blockchain
Bitcoin
Bitcoin Cash
Difficulty Algorithm
Mining
Coin-Hopping
Publication Status
Published
Start Date
2021-05-03
Finish Date
2021-05-06
Coverage Spatial
Sydney, Australia