Analysis of the Sybil defense of Duniter-based cryptocurrencies

TL;DR

This paper analyzes the effectiveness of the Web of Trust system in Duniter-based cryptocurrencies against Sybil attacks, showing that real-world constraints help prevent large-scale attacks despite theoretical vulnerabilities.

Contribution

It provides an analysis of the maximum size of Sybil attacks possible under simplified graph rules and demonstrates real-world system resilience.

Findings

Theoretical analysis shows potential for large Sybil attacks without constraints.

Real-world social and time constraints limit attack sizes in Duniter systems.

System can prevent large attacks in practice despite theoretical vulnerabilities.

Abstract

Duniter-based cryptocurrencies, which are providing a kind of universal basic income, are using a system called "Web of Trust" based on a social network whose evolution is subject to graph theoretical rules, time constraints and a licence in order to avoid large Sybil attacks. We investigate in this article the largest size of a Sybil attack that a simplified version of the graph theoretical rules of a Web of Trust can undergo depending on the number of attackers and on the parameters of the system. We show that even if in theory, without considering social and time constraints, this system cannot in general prevent huge attacks, in the real-world case of a Duniter-based cryptocurrency (with thousands of users), the system can prevent attacks of large size with only graph theoretical rules.