# StakeCube: Combining Sharding and Proof-of-Stake to build Fork-free Secure Permissionless Distributed Ledgers

## TL;DR

This paper introduces StakeCube, a scalable permissionless blockchain that combines sharding and proof-of-stake to prevent forks, enhance security, and improve efficiency without relying on synchrony assumptions.

## Contribution

It proposes a novel architecture integrating randomized sharding with Byzantine agreement and UTXO model, ensuring fork-free security in proof-of-stake blockchains.

## Key findings

- Achieves negligible probability of forks.
- Robust against eclipse attacks through induced churn.
- Works against adaptive adversaries without strong synchrony assumptions.

## Abstract

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.