A Trailing Finality Layer for Zcash

This book introduces and specifies a Trailing Finality Layer for the Zcash network. This is version 0.1.0 of the book.

This design augments the existing Zcash Proof‑of‑Work (PoW) network with a new consensus layer which provides trailing finality. This layer enables transactions included via PoW to become final which assures that they cannot be reverted by the protocol. This enables safer and simpler wallets and other infrastructure, and aids trust-minimized cross-chain bridges. This consensus layer uses Proof-of-Stake consensus, and enables ZEC holders to earn protocol rewards for contributing to the security of the Zcash network. By integrating a PoS layer with the current PoW Zcash protocol, this design specifies a hybrid consensus protocol dubbed PoW+TFL.

The rest of this introductory chapter is aimed at a general audience interested in the context of this proposal within Zcash development, status and next steps, motivations, a primer on finality, and tips to get involved.