Zcash activates Ironwood upgrade with new shielded pool

Zcash is about to implement a major network upgrade. At block height 3,428,143, expected around 13:00 UTC on 28 July 2026, the Zcash network will activate the so-called Ironwood upgrade. This update introduces a new shielded pool and improved security mechanisms for the ZEC supply.

Zcash is available at OKX and Bybit.

What changes with Ironwood?

The Ironwood upgrade, part of Network Upgrade 6.3 (NU6.3), introduces an entirely new shielded pool. This pool uses the Action framework and the Halo2 proof system from Orchard, but adds its own elements: a new note commitment tree, a nullifier set, a chain value pool and chain history metadata. All of this is rolled out via a new v6 transaction format.

A notable part of the upgrade is support for quantum recoverable notes. In addition, Ironwood introduces a so-called turnstile mechanism, intended to strengthen the verification of the ZEC supply. This mechanism comes in response to concerns about a potential counterfeit vulnerability in the existing Orchard pool, where extra coins could be created illicitly without being immediately visible.

Zebra 6.0.0 and the testnet activation

The upgrade is made technically possible via Zebra 6.0.0, the reference implementation of the Zcash protocol. According to the official announcement from the Zcash Foundation, this version activates the NU6.3 shielded pool and the v6 transaction format on mainnet at the aforementioned block height. On the testnet, activation is scheduled at block height 4,134,000.

The Ironwood upgrade is thus one of the most significant changes to the Zcash network in recent times. With stronger supply verification and a future-proof shielded pool, the project aims to increase trust in the integrity of ZEC, especially now that quantum computing is increasingly seen as a potential threat to cryptographic systems.