Zcash's 'Ironwood' Upgrade Near… Revises Circulation Verification Structure

Zcash will implement the 'Ironwood' network upgrade at block height 3,428,143 on July 28 (local time). The upgrade is designed to allow all users to independently verify the integrity of Zcash circulation. Scheduled for the NU6.3 version, the upgrade will activate around noon UTC on July 28. Key changes include deactivating the existing Orchard shield pool and introducing a revised shield pool with updated Orchard circuits. This prevents more ZEC from leaving than legitimately entered through the previous pool. The Zcash Open Development Research Lab (ZODL) confirmed the mainnet activation two days prior, emphasizing that Ironwood maintains privacy verification while ensuring supply constraints. The update addresses a critical forgery vulnerability discovered in Orchard shield pools, with Shielded Labs researcher Taylor Holibius identifying the flaw. ZODL implemented an emergency network upgrade to fix the issue, noting the vulnerability's practical exploitation likelihood is low. However, existing Orchard transaction data remained shielded, making independent verification of forged ZEC creation difficult before the fix. Ironwood transitions to a new shield pool with updated circuits, allowing anyone operating nodes to verify supply constraints post-upgrade. Post-upgrade, sending or receiving ZEC within Orchard pools will be disabled, with funds only exiting via Zcash's existing tumbling mechanism. Zcash describes this structure as preventing potential forged supply from increasing circulation. Market participants are closely monitoring the upgrade as it represents a strategic technological update that maintains privacy while enabling external verification of supply integrity. The network transition aims to reduce uncertainty around supply soundness, particularly since the vulnerability resided in the Orchard pool.