Zcash has activated Ironwood (Network Upgrade 6.3) on mainnet, marking the next stage in the evolution of its shielded protocol.
On May 29, a vulnerability affecting the Orchard shielded pool was responsibly disclosed during a security audit. Although there is no evidence it was ever exploited, the issue could have affected one of Zcash’s most important guarantees: ensuring that no more ZEC can exist than the protocol allows.
NU6.2 addressed the immediate problem by deploying a corrected Orchard circuit and safely restoring mining of Orchard shielded transactions. Ironwood builds on that work with a long-term solution, introducing a new shielded pool and beginning a gradual transition away from Orchard.
Key Takeaways
Ironwood is Zcash’s latest network upgrade.
It introduces a new shielded pool for future shielded activity.
Existing Orchard funds remain safe and under their owners’ control.
Wallets will gradually support migrating funds to the new pool.
Most users only need to keep their wallet updated and follow their wallet’s guidance.
Rather than continuing to build on Orchard, the Zcash ecosystem chose to introduce a new shielded pool designed for the network’s next chapter.
One of Ironwood’s primary goals is restoring independently verifiable supply integrity, allowing anyone running a full node to verify the entire circulating supply without relying on assumptions about the previous pool.
To further strengthen confidence in this new design, Project Tachyon completed a formal verification of Ironwood’s balance integrity, publishing more than 2,700 machine-checked theorems written in Lean.
The verification confirms that Ironwood’s zk-SNARK, transaction circuit, and ledger rules prevent undetectable counterfeiting by ensuring notes cannot be created from nothing, spent twice, spent without authorization, or used to withdraw more ZEC than entered the shielded pool.
It also connects the mathematical model to the deployed Rust verifier through a reproducible verifier fingerprint, providing additional confidence that the implementation matches the verified design.
Ironwood begins a gradual transition that gives wallets, exchanges and other infrastructure time to adopt the new pool while keeping the network stable.
Nothing changes immediately for users.
If you already have shielded funds in Orchard, they remain under your control and are not moved automatically when Ironwood activates.
As funds gradually move to the new shielded pool, they pass through a mechanism known as the turnstile. Think of it as an accounting checkpoint that ensures no more value can leave Orchard than legitimately existed there, helping maintain the network’s monetary integrity throughout the transition.
Compatible wallets will handle this migration over time, allowing users to move to Ironwood without disrupting normal use of the network.
The transition to Ironwood happens through wallet updates.
As wallets add support for Ironwood, they’ll provide a way to migrate existing Orchard funds. Depending on the wallet, this may happen through a guided migration flow or as part of normal shielded transactions.
Users don’t need to rush or perform complicated steps. The recommendation is simple:
Keep your wallet updated.
Install updates only from official sources.
Follow the migration guidance provided by your wallet.
While each wallet may introduce the migration differently, the goal is the same: making the transition as simple and secure as possible.
For wallet-specific migration instructions, refer to the official resources below:
Additional Ironwood resources:
ZODL Ironwood Migration Hub – Wallet support, migration guidance, and ecosystem resources.
ZecStats Ironwood Dashboard – Live migration statistics and adoption progress.
CipherScan Ironwood Explorer – Track Ironwood activity and explore the new shielded pool.
Ironwood marks the beginning of Zcash’s transition to a new shielded pool.
As wallets, exchanges and other infrastructure adopt the upgrade, more shielded activity will naturally move to the new pool. For most users, the experience should remain familiar: keep your wallet updated, follow your wallet’s guidance and continue using shielded transactions as usual.
Behind the scenes, Ironwood strengthens one of Zcash’s core promises by reinforcing the network’s long-term monetary integrity while preserving the privacy that shielded transactions are designed to provide.
This milestone was made possible through the collaboration of developers, researchers, and organizations across the Zcash ecosystem. Their coordinated work, from identifying and addressing the Orchard vulnerability to designing and deploying Ironwood, helped ensure a smooth transition while preserving the network’s security and privacy.
Thank you to everyone who contributed to making this possible. 💛
Onward!