Zcash Network Upgrades

Over the years, Zcash has introduced significant changes and improvements to the protocol, and today, we explore every one of these upgrades:

OverWinter: Activated at block 347500, mined June 26, 2018. Overwinter was the first network upgrade for Zcash after the initial launch. Overwinters primary goal was to strengthen the protocol for future network upgrades. At the core of Overwinter is replay protection for network upgrades, versioning, enhancing performance for transparent transactions, a new feature of transaction expiry.

Sapling: Activated at block 419200, mined October 29, 2018. This is the second major impressive upgrade for the Zcash network, primarily focusing on improving the efficiency of zk-SNARKs for shielded transactions. During the advent of sapling’s release, there were several looming challenges hovering around zk-SNARKs, from upgradability challenges to implementation complexities to trusted setup requirements. Thankfully, sapling enhanced the efficiency of zk-SNARK proof creation to broaden the potential adoption of the cryptocurrency, which we are enjoying today! Another notable setup envisioned for sapling was (a public parameter generation ceremony) which is also what the Zcash team was looking to improve upon.

Zcash Blossom: Activated at block 653600, mined December 11, 2019. This crucial network upgrade was designed to improve scalability and user experience by cutting block times in half to about 75 seconds. Implications? Transaction confirmations became faster, network throughput was doubled and transaction fees were at low cost. The Blossom upgrade immediately demonstrates that the Zcash network can make pragmatic engineering decisions to increase the capacity of the network while maintaining our high standards for security and reliability.

HeartWood: Activated at block 903000, mined July 16, 2020. The sole purpose of Heartwood is to enable more third-party integrations and enhanced privacy through a shielded Coinbase that allows miners to receive rewards in shielded addresses. Additionally, the Heartwood is backed by enhanced network decentralization and interoperability. The heartwood upgrade also integrated Flyclient, which enables lightweight clients to verify transactions efficiently, improving scalability and third-party integration. It is also worth mentioning that the shielded Coinbase, known as ZIP 213, seeks to modify Zcash consensus rules so that Coinbase funds can be mined to shielded Sapling addresses. Before the sapling upgrade, shielded Coinbase was not feasible because shielded transactions required significant memory and CPU resources to create.

Canopy: Activated at block 1046400, mined November 18, 2020. This upgrade was backed by both Electric Coin Co (ECC) and the Zcash Foundation. Canopy marked the end of the founders reward, a new funding mechanism was introduced (Zcash development fund), and a new governance model, supported the continued funding for the Zcash ecosystem. For Canopy, a new development fund will be established for the next four years. 80% of the mining reward will go to the miners. 20%, which is the remainder, will be divided between the new Major Grants Fund (8%), Electric Coin Co (7%), and the Zcash Foundation (5%). The name ‘canopy’ reflects Zcash’s mission to create a sustainable and thriving ecosystem while staying true to its principles of privacy and decentralization.

NU5: Activated at block 1687104, mined May 31, 2022. It is worth mentioning that Zcash Network Upgrade 5 marks the dawn of an important milestone for the cryptocurrency since its inception in 2016. Being the sixth major for Zcash, NU5 featured the orchard shielded protocol, unified addresses, as well as the halo provision system. The Zcash NU5 upgrade is a continued evolution of the zk-SNARK technology stack built to eliminate the trusted setup and upgrade the protocol’s underlying cryptography security. NU5 is also endorsed by ECC and the Zcash Foundation.

NU6: NU6 implemented a new Zcash development fund (Hybrid Deferred Dev Fund transitioning to a non-direct funding model) and then will set up a lockbox where a proportion of issuance will be reserved for any future decentralized grants funding. The release of these funds will be solely governed by a mechanism determined by the Zcash community in the future. NU6s mission is to reduce block subsidy and to establish a decentralized funding model via a lockbox mechanism for ensuring enhanced transparency while strengthening privacy.