Zcash confirms July 28 Ironwood activation after Orchard bug

Zcash has scheduled its Ironwood network upgrade for July 28, setting the activation date for the protocol change designed to close the Orchard shielded pool and help verify whether the previously disclosed vulnerability was ever exploited.

Zcash core developer Sean Bowe said on Thursday that the network will activate Ironwood at block height 3,428,143, expected at around 8 a.m. EST on July 28, confirming a one-week delay from the previously planned July 21 rollout.

The confirmation follows earlier concerns raised by Shielded Labs that exchanges, mining pools, and wallet providers might not have enough time to prepare because many were also replacing Zcash’s long-running zcashd software with the new Z3 stack, which includes Zebra, Zaino, and Zallet. 

Although the organization floated delaying the upgrade, Bowe’s announcement confirms the activation will proceed later this month.

Ironwood was proposed after developers disclosed an “infinity” bug in Zcash’s Orchard shielded pool, the network’s primary privacy-focused transaction system. Shielded Labs said the flaw could theoretically have allowed an attacker to create unlimited counterfeit ZEC, although it also said it had found no evidence that the vulnerability had been exploited.

Emergency updates addressed the software flaw before it became public. Developers first disabled Orchard transactions through a temporary network update before activating the NU6.2 hard fork on June 3 to fix the underlying issue and restore the pool.

Once Ironwood goes live, the existing Orchard pool will stop accepting new activity and users will instead move funds into a newly created private pool. According to Shielded Labs, coins leaving Orchard must pass through an accounting checkpoint before entering Ironwood, creating a process that could reveal evidence if any counterfeit ZEC had been created through the earlier bug.

The organization said users migrating funds effectively force any hypothetical counterfeiter to either move fake coins and risk exposing them or leave those coins behind without a future way to transfer them.

ZEC has recovered after sharp post-disclosure decline

Following public disclosure of the Orchard vulnerability on June 3, ZEC fell about 50% from $602.68 to $299.25. The token has since recovered part of those losses and was trading at $492.61 at the time of writing.

Separately, Zcash passed another network milestone this week. A post from ruZCASH on Monday showed the circulating supply had reached 16,806,723 ZEC, meaning more than 80% of the cryptocurrency’s maximum 21 million supply has now been issued.