Ignacio Amores-Sesar; Christian Cachin; Jovana Micic; University of Bern;
Abstract
The Ripple network is one of the most prominent blockchain platforms and its native XRP token currently has the third-largest cryptocurrency market capitalization. The Ripple consensus protocol powers this network and is generally considered to a Byzantine fault-tolerant agreement protocol, which can reach consensus in the presence of faulty or malicious nodes. In contrast to traditional Byzantine agreement protocols, there is no global knowledge of all participating nodes in Ripple consensus; instead, each node declares a list of other nodes that it trusts and from which it considers votes.
Previous work has brought up concerns about the liveness and safety of the consensus protocol under the general assumptions stated earlier, and there is currently no appropriate understanding of its workings and its properties in the literature. This paper makes two contributions. It first provides a detailed, abstract description of the protocol, which has been derived from the source code. Second, the paper points out that the abstract protocol may violate safety and liveness in several simple executions under relatively benign network assumptions.
