Zcash Founder Says Ironwood Will Verify ZEC Supply On Day One

Zcash founder Zooko Wilcox says the proposed Ironwood upgrade will give users immediate, trustless verification that ZEC’s circulating supply is sound from the first block of activation. His comments address a central concern in the Zcash community following the disclosure of a recently remediated Orchard vulnerability: whether users can verify the supply without relying on developers, auditors, or post-hoc assumptions.

In a post on X and a follow-up discussion on the Zcash Community Forum, Wilcox argued that Ironwood’s purpose is not primarily to prove whether counterfeiting ever occurred inside Orchard. Instead, he framed the upgrade as a way to make the current circulating supply independently verifiable by any user running a full node.

“When Zcash Ironwood activates, you will immediately, on Day 1 of Ironwood, gain trustless verification from your own full node that the actual supply of Zcash is correct,” Wilcox wrote, referring to “16M ZEC now, 21M ZEC eventually.”

Zcash Ironwood To Enable Trustless Supply Checks

The distinction matters because the Orchard pool is shielded. That privacy property is central to Zcash’s design, but it also complicates the question of whether a past soundness bug could have been exploited without leaving the kind of public trace visible in a transparent ledger. Wilcox’s response is to separate two issues that have become conflated in the debate: whether counterfeit coins were ever created, and whether the current supply can be verified as sound after Ironwood.

“This appears to be super confusing to almost everyone, because they are confusing two different things: No counterfeit coins were created. The current supply is sound,” Wilcox wrote. “These are different things! I’m prioritizing the second one.”

Under the Ironwood proposal, the old Orchard pool would effectively be prevented from continuing as an active internal circulation venue. Transactions creating new outputs in the old Orchard pool would be rejected, meaning funds could no longer keep moving privately inside that pool after activation. Instead, funds would have to exit through Zcash’s turnstile accounting mechanism before entering the new Ironwood pool.

That turnstile is the key to the argument. It tracks how much ZEC legitimately entered and exited a pool and blocks attempts to move out more than the amount that entered. According to Wilcox, that means users do not need to wait for every Orchard user to migrate, nor rely on game-theoretic assumptions about how a hypothetical attacker might behave.

“And what I said above — that you will immediately gain that trustless, local verification of the soundness of the Zcash supply — is true regardless of whether or not there are any counterfeit coins in the Orchard pool,” he wrote. “How is this possible!? Because Ironwood will, on Day 1, in the first block that activates Ironwood, snuff out any excess ZEC in the Orchard pool.”

Wilcox specified the relevant threshold as the amount “legitimately part of the supply of ZEC in the Orchard pool,” which he put at 4.5 million ZEC. Any excess ZEC above that would be unable to remain economically useful under the new rules, because it could not continue circulating within the old Orchard pool or escape into another pool beyond the turnstile limit.

“It will snuff out any excess ZEC immediately, trustlessly, and globally,” he added. “It will snuff out any excess ZEC regardless of whether there actually is any excess ZEC. If there isn’t, then all Ironwood does is give you the ability to prove to yourself that there isn’t.”

Wilcox said he personally believes there is no counterfeit ZEC, citing reasons he said he had previously given. But he emphasized that Ironwood is designed to remove the need for trust in his assessment, or in any other individual’s judgment. In his forum post, he laid out two possible worlds: one in which an unlimited amount of counterfeit ZEC was created inside Orchard before the vulnerability was closed, and one in which it was not. In both, he argued, Ironwood should allow users to verify on Day 1 that no more than 16 million ZEC is currently circulating.

The proposal may also produce evidence over time about whether Orchard was ever exploited. If no excess ZEC attempts to leave the old pool as users migrate, that would support the view that no counterfeiting occurred. If excess ZEC does try to leave, the turnstile should reject it, preserving the circulating supply while exposing that counterfeiting had taken place.

At press time, ZEC traded at $