Zcash seals $1.7 billion shielded pool as Ironwood upgrade activates
Reported by CoinDesk · AI-assisted summary by ChikoCorp AI News Desk
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Zcash has activated its Ironwood upgrade (also called NU6.3) at block 3,428,143, which effectively sealed off the previous private "shielded pool" known as Orchard. This pool contained approximately 3.66 million ZEC coins, valued at around $1.7 billion. The Ironwood upgrade introduced a new shielded pool starting with zero coins, requiring users to voluntarily migrate their funds from Orchard to the new pool. Until migration occurs, the large bulk of Zcash’s private supply remains locked in the sealed Orchard pool, which cannot now accept new coins.
The impetus for this major upgrade was the discovery of a previously undisclosed bug in Orchard’s zero-knowledge proof circuit that could have allowed undetectable creation of counterfeit ZEC coins. This vulnerability was present since Orchard launched in May 2022. While CoinDesk research found no evidence that counterfeit coins were minted—since funds leaving the pool did not show abnormal activity consistent with cashing out fake coins—the zero-knowledge proofs provide no direct record to completely rule out abuse. To mitigate this risk, the Ironwood upgrade implemented a turnstile mechanism at the pool boundary that caps withdrawals to the amount verifiably deposited, preventing counterfeit coins from exiting the shielded pool.
Beyond addressing the bug, Ironwood brings notable technical improvements. It introduces quantum-resilient record-keeping designed to protect transaction data from future quantum computer attacks. Additionally, the new pool’s proof circuit is undergoing formal verification, a mathematical process to ensure the code behaves correctly in all cases, aiming to prevent similar bugs that affected Orchard. These measures enhance the security and reliability of Zcash’s private transaction layer.
As of the report’s release, about 1,500 ZEC had moved to the new shielded pool, but migration remains entirely optional and user-driven. The speed at which the 3.66 million ZEC in Orchard transfers will determine how quickly the network benefits from Ironwood’s protections. Meanwhile, ZEC traded near $463, down 8% on the day of the upgrade but still up roughly tenfold over the past year, reflecting broader market dynamics separate from the protocol changes.