Antoine Durand

Antoine Durand, Emmanuelle Anceaume, Romaric Ludinard

Our work focuses on the design of a scalable permissionless blockchain in the proof-of-stake setting. In particular, we use a distributed hash table as a building block to set up randomized shards, and then leverage the sharded architecture to validate blocks in an efficient manner. We combine verifiable Byzantine agreements run by shards of stakeholders and a block validation protocol to guarantee that forks occur with negligible probability. We impose induced churn to make shards robust to eclipse attacks, and we rely on the UTXO coin model to guarantee that any stakeholder action is securely verifiable by anyone. Our protocol works against adaptive adversary, and makes no synchrony assumption beyond what is required for the byzantine agreement.

Antoine Durand, Elyes Ben-Hamida, David Leporini et al.

In the light of the recent fame of Blockchain technologies, numerous proposals and projects aiming at better practical viability have emerged. However, formally assessing their particularities and benefits has proven to be a difficult task. The aim of this work is to compare the fundamental differences of such protocols to understand how they lead to different practical performances. To reach this goal, we undertake a complexity analysis of a wide range of prominent distributed algorithms proposed for blockchain systems, under the lens of Total Order Broadcast protocols. We sampled protocols designed for very different settings and that use a broad range of techniques, thus giving a good overview of the achievements of state-of-the-art techniques. By analyzing latency and network usage, we are able to discuss each protocol's characteristics and properties in a consistent manner. One corollary result to our work is a more robust criteria to classify protocols as permissioned or permissionless.