Zcash Ironwood Upgrade Strengthens Circulating Supply Verification

Zcash has activated its Ironwood network upgrade, replacing the vulnerable Orchard shielded pool with a hardened system to restore independent verification of the cryptocurrency's circulating supply.

The Ironwood upgrade was implemented at block height 3,428,143 on July 28 and includes a separate Ironwood shielded pool, a new transaction format, and a mandatory accounting checkpoint for funds leaving Orchard.

Orchard has been restricted to withdrawals, while new shielded payments are now directed to Ironwood. This change follows the discovery of a critical cryptographic weakness in Orchard that could have allowed a malicious user to generate counterfeit notes.

Zcash's existing turnstile architecture prevented the global supply from exceeding its 21 million ZEC cap, but the vulnerability weakened confidence that every coin circulating privately inside Orchard had been legitimately created.