Larger-scale Nakamoto-style Blockchains Don't Necessarily Offer Better Security
Jannik Albrecht, Sebastien Andreina, Frederik Armknecht, Ghassan Karame, Giorgia Marson, Julian Willingmann
IEEE Symposium on Security and Privacy 2024 · Day 2 · Continental Ballroom 6
The prevailing intuition in blockchain security suggests that increasing the number of nodes in a network inherently leads to greater security due to enhanced decentralization and a reduced risk of a majority of nodes being corrupted. This talk challenges this fundamental assumption, presenting a detailed analysis that reveals a critical flaw in existing security models and demonstrates that, under certain conditions, adding more nodes to a Nakamoto-style blockchain can paradoxically *weaken* its security guarantees. The research, a collaborative effort from Ruhr University Bochum and NEC Labs Europe, introduces a novel security metric that reconciles the competing forces of increased network delay and distributed power, offering a more comprehensive understanding of blockchain robustness at scale.
AI review
This research directly challenges the fundamental, simplistic notion that more nodes inherently lead to better blockchain security. By introducing a novel security metric and empirically characterizing network delays, the authors expose a critical "turning point" where network expansion paradoxically degrades security. This is a must-see for anyone serious about designing or securing large-scale Nakamoto-style systems.