Zcash founder Zooko Wilcox has laid out a strategy to freeze any potential fake ZEC tokens during the network's upcoming Ironwood hard fork, scheduled for July 28. The plan, which involves temporary freezes on wallets and exchanges this week, aims to protect the privacy-focused cryptocurrency from counterfeit coins before the upgrade takes effect.
Why the freeze is needed
Fake ZEC tokens, sometimes called “zombie” coins, can be created through exploits in the network's shielded transaction system. Wilcox's strategy targets these illegitimate tokens before they can circulate further. The move comes as the Zcash community prepares for the Ironwood upgrade, which includes changes designed to improve network security and scalability.
Wilcox didn't specify exactly how many fake ZEC might be out there, but the freeze is meant to isolate any suspicious holdings. Wallets and exchanges that comply with the temporary freeze will help prevent bad actors from moving the counterfeit coins before the hard fork.
How the Ironwood hard fork will work
The Ironwood hard fork is a planned network upgrade that will introduce new consensus rules. As part of that process, Wilcox revealed a method to identify and freeze addresses that hold potentially fake ZEC. The freeze won't be permanent — it's designed to last only until the hard fork activates, after which the network's new rules should make it harder to create fake tokens in the first place.
Zcash users won't need to do anything to prepare, but exchanges and wallet providers will have to apply the temporary freeze to affected addresses. Wilcox said the strategy relies on cooperation from major platforms that handle ZEC transactions.
Immediate impact on wallets and exchanges
Starting this week, some wallets and exchanges will temporarily block transactions involving addresses flagged as containing potential fake ZEC. The goal is to lock those tokens in place until the Ironwood hard fork can permanently invalidate them. For most users, the disruption should be minimal — only accounts with suspicious activity are likely to be affected.
Wilcox didn't name specific exchanges or wallets that have agreed to participate, but he said the plan has support from key players in the Zcash ecosystem. The freeze is expected to last just a few days, ending when the hard fork goes live on July 28.
The Zcash team has been monitoring the fake ZEC problem for months. The Ironwood hard fork includes a change to the network's shielded pool rules that should prevent the same type of exploit from recurring. Until then, the temporary freeze is a stopgap measure.
The hard fork itself is still on track for July 28. After that, the frozen tokens will be rendered unusable, and the Zcash network will move forward with its new rules. Whether any fake ZEC slips through the freeze remains an open question — but Wilcox and the development team are betting that this week's action will catch the bulk of them.
