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Green Paper


This document outlines the rationale and main design ideas behind the consensus layer of Chia\textrm{{\sf Chia}}, a longest-chain blockchain akin to Bitcoin. It achieves comparable security guarantees as Bitcoin's Proof of Work (PoW) based Nakamoto consensus, while using Proofs of Space in combination with Verifiable Delay Functions (VDFs) to achieve Sybil resistance. This makes Chia\textrm{{\sf Chia}} much more sustainable and also more decentralized than a PoW based blockchain could be.

We outline the challenges one must solve when replacing proofs of work with an efficient proof system like proofs of space, and how they are addressed in Chia\textrm{{\sf Chia}}. Here efficient means that once the resource (like space or stake) is available, computing many proofs is basically as cheap as computing one.

This document is not a formal specification of Chia\textrm{{\sf Chia}}. Instead, it aims at readers who want to understand the design choices of Chia’s\textrm{{\sf Chia's}} consensus, and are interested in permissionless longest-chain blockchains from efficient proof systems in general.

Precursor Consensus Green Paper

In order to provide historical context, the Green Paper's previous version that discusses a precursor consensus which was never implemented is available here for viewing: Precursor Green Paper.