The Doctoral School in Science and Engineering is happy to invite you to Flaviene SCHEIDT DE CRISTO’s defence entitled
Improving Scalability and Optimizing Message Dissemination on the XRP Ledger
Supervisor: Prof. Radu STATE
Blockchains have become crucial in numerous fields, notably within financial applications. The advent of Bitcoin coincided with the emergence of a global economy highly dependent on digital transactions, stimulating the development of numerous blockchains that aim to address different challenges. The XRP Ledger (XRPL) is an example of a blockchain designed to address cross-currency payments. Unlike its counterparts, the XRPL does not employ resource-intensive consensus mechanisms such as Proof of Work, employing instead a Federated Byzantine Agreement (FBA) consensus protocol, in which subnets of validators vote to determine the next version of the ledger.
The XRPL network allows any node to act as a validator, but its consensus mechanism relies on a trusted group of validators called the Unique Nodes List (UNL). In its current implementation, the XRPL relies on a single UNL, curated by the XRP Ledger Foundation. The dependence on this centrally managed UNL raises issues regarding authority distribution and network scalability. Although the XRPL is decentralized in terms of communication, it does not feature dynamic trust overlay rearrangement, resulting in limited authority dispersion and possible performance problems as the network grows.
This thesis investigates ways to enhance the dispersion of authority and node-wise scalability of the XRPL. First, we explore a tool that has the potential of diversifying UNLs to achieve higher trust autonomy, we then propose the use of pubsub dissemination to reduce message overhead and improve scalability. The research also addresses key questions on the impact of pubsub mechanisms on the performance of the XRPL, aiming to provide insight into tuning parameters for optimal network efficiency. The ultimate goal is to determine how pubsub dissemination can enhance the scalability and performance of blockchains using FBA consensus, specifically within the context of the XRPL.