Zcash Activates Ironwood Upgrade to Replace Vulnerable Orchard Pool

The Ironwood upgrade introduces a new accounting boundary with its own note commitment tree and chain value pool, enabling nodes to track shielded activity independently. A critical feature of this transition is the implementation of a turnstile mechanism, which prevents the exit of more value from the older Orchard pool than was originally deposited. While Orchard remains accessible for fund withdrawals, it no longer supports new shielded transactions, effectively entering an exit-only phase. Current migration data indicates that approximately 40,207 ZEC have moved to the new pool, while roughly 3.6 million ZEC remain in Orchard.

Formal Verification and Security

To ensure the integrity of the new protocol, Project Tachyon utilized the Lean programming language to complete a machine-checked mathematical proof. Comprising over 2,700 theorems, this verification confirms that the new shielded pool cannot create value beyond what has publicly entered it. Zcash co-founder Sean Bowe stated that this cross-team collaboration eliminates sources of undetectable counterfeiting bugs from the protocol. Additionally, Ironwood integrates ZIP 2005 quantum-recoverable notes, creating a foundation for future cryptographic resilience. The upgrade also marks a transition in infrastructure, as the network now requires the Zebra node implementation, deprecating the older zcashd software.