938 research outputs found
Decentralization in Bitcoin and Ethereum Networks
Blockchain-based cryptocurrencies have demonstrated how to securely implement
traditionally centralized systems, such as currencies, in a decentralized
fashion. However, there have been few measurement studies on the level of
decentralization they achieve in practice. We present a measurement study on
various decentralization metrics of two of the leading cryptocurrencies with
the largest market capitalization and user base, Bitcoin and Ethereum. We
investigate the extent of decentralization by measuring the network resources
of nodes and the interconnection among them, the protocol requirements
affecting the operation of nodes, and the robustness of the two systems against
attacks. In particular, we adapted existing internet measurement techniques and
used the Falcon Relay Network as a novel measurement tool to obtain our data.
We discovered that neither Bitcoin nor Ethereum has strictly better properties
than the other. We also provide concrete suggestions for improving both
systems.Comment: Financial Cryptography and Data Security 201
Impact of Geo-distribution and Mining Pools on Blockchains: A Study of Ethereum
Given the large adoption and economical impact of permissionless blockchains,
the complexity of the underlying systems and the adversarial environment in
which they operate, it is fundamental to properly study and understand the
emergent behavior and properties of these systems. We describe our experience
on a detailed, one-month study of the Ethereum network from several
geographically dispersed observation points. We leverage multiple geographic
vantage points to assess the key pillars of Ethereum, namely geographical
dispersion, network efficiency, blockchain efficiency and security, and the
impact of mining pools. Among other new findings, we identify previously
undocumented forms of selfish behavior and show that the prevalence of powerful
mining pools exacerbates the geographical impact on block propagation delays.
Furthermore, we provide a set of open measurement and processing tools, as well
as the data set of the collected measurements, in order to promote further
research on understanding permissionless blockchains.Comment: To appear in 50th IEEE/IFIP International Conference on Dependable
Systems and Networks (DSN), 202
Understanding and Hardening Blockchain Network Security Against Denial of Service Attacks
This thesis aims to examine the security of a blockchain\u27s communication network. A blockchain relies on a communication network to deliver transactions. Understanding and hardening the security of the communication network against Denial-of-Service (DoS) attacks are thus critical to the well-being of blockchain participants. Existing research has examined blockchain system security in various system components, including mining incentives, consensus protocols, and applications such as smart contracts. However, the security of a blockchain\u27s communication network remains understudied.
In practice, a blockchain\u27s communication network typically consists of three services: RPC service, P2P network, and mempool. This thesis examines each service\u27s designs and implementations, discovers vulnerabilities that lead to DoS attacks, and uncovers the P2P network topology. Through systematic evaluations and measurements, the thesis confirms that real-world network services in Ethereum are vulnerable to DoS attacks, leading to a potential collapse of the Ethereum ecosystem. Besides, the uncovered P2P network topology in Ethereum mainnet suggests that critical nodes adopt a biased neighbor selection strategy in the mainnet. Finally, to fix the discovered vulnerabilities, practical mitigation solutions are proposed in this thesis to harden the security of Ethereum\u27s communication network
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