What is Heartwood?
Heartwood is the fourth major network upgrade for Zcash, and in accordance with the Zcash trademark agreement, it is endorsed by both Electric Coin Co. and the Zcash Foundation.
Heartwood enables more third-party integrations and better privacy through shielded coinbase. The community chose this name to evoke themes of faster growth, adoption and expansion. The two ZIPs in Heartwood are ZIP-221 (Flyclient) and ZIP-213 (Shielded Coinbase).
This ZIP enables efficient proofs of Proof-of-Work for light clients. In addition to enabling improved light-client wallets, this improves many cross-chain protocols. This ZIP specifies modifications to be made to the Zcash block header format to include Merkle Mountain Range (MMR) commitments. The MMR that produces the root provides a number of benefits to light clients, and enables future specification of the FlyClient protocol.
This ZIP defines modifications to the Zcash consensus rules that enable coinbase funds to be mined to shielded Sapling addresses. It does not disable the use of transparent addresses in coinbase transactions.
Prior to the Sapling upgrade, shielded coinbase was not feasible because shielded transactions required significant memory and CPU resources to create. The Sapling network upgrade deployed architectural changes and performance improvements that make shielding funds directly in the coinbase transaction possible. The ZIP does not require that all coinbase must be shielded immediately from activation of the network upgrade. This is so that miners and mining pools may gradually migrate from their existing transparent addresses to Sapling addresses. Shielded coinbase is an important milestone for Zcash network privacy and the overall size of our anonymity set. We anticipate that ZIP 213 will drive more demand for shielded support across the ecosystem.
How do I upgrade?
If you are unsure about how to upgrade your node, don’t worry! The Zcash user guide has comprehensive sections on upgrading nodes, whether they were installed from source code or the Debian package. A careful read of this guide should answer most upgrade-related questions.