Zcash activates Ironwood, migrates 3.7M ZEC

Zcash activated the Ironwood upgrade on its network in July 2026. The upgrade retires the Orchard shielded pool and requires holders to move about 3.7 million ZEC into a new shielded pool following the disclosure of a critical counterfeiting vulnerability.

The flaw was discovered on May 29, 2026, by security researcher Taylor Hornby using an advanced AI model. Developers deployed an emergency fix in early June and publicly disclosed the issue on June 3. They reported no evidence the bug had been exploited but acknowledged there is no cryptographic way to prove counterfeit coins were never created before the fix.

Ironwood implements a “turnstile” accounting rule that caps withdrawals from the retired Orchard pool to the amount that can be proven as deposited. The rule prevents any counterfeit ZEC created by the Orchard flaw from entering circulation. The upgrade also adds quantum-resistant transaction records and a formally verified proof circuit intended to reduce the likelihood of similar cryptographic defects.

Approximately 3.7 million ZEC sat in Orchard when Ironwood went live, a stake worth about $1.7 billion at the time of migration. Public disclosure of the vulnerability in June triggered a steep selloff in ZEC and erased billions from the token’s market value before the emergency fixes and the Ironwood upgrade were completed. Developers and ecosystem partners coordinated a confidential response in June that involved protocol teams, miners, exchanges and wallet providers prior to public patches.

The required migration creates privacy tradeoffs. Moving funds from Orchard to the new pool can expose links between wallet balances and network addresses if users do not take protective steps. Zooko Wilcox urged users “not to rush the migration” and recommended using anonymity tools such as Tor or a VPN while moving funds. Decentralized infrastructure providers warned of operational risks for users who migrate without additional protections.

Zcash launched in October 2016 and uses zero-knowledge proofs known as zk-SNARKs to enable shielded transactions that hide sender, recipient and amount. The protocol supports transparent addresses, which display transaction history like Bitcoin, and shielded addresses, which hide transaction details. Wallets and services have added features that encourage shielding; some now default to moving funds into shielded pools.

At launch Zcash used a multi-party “trusted setup” ceremony to create cryptographic parameters. Former Electric Coin Company CEO Josh Swihart described a participant in that ceremony as acting “as a service, as a public good, and believing in privacy.” The protocol currently runs a proof-of-work consensus mechanism using the Equihash algorithm.

Miners receive 80% of each block reward while 20% supports development funds for organizations that maintain the ecosystem. The next block reward halving is scheduled for November 2028, when the community will review funding arrangements.

Privacy-focused cryptocurrencies have faced regulatory scrutiny and periodic delistings from exchanges over concerns about illicit finance. Exchanges have removed and later relisted Zcash at different times as features and controls changed.

Developers continue work on node and wallet software and on hardening the protocol after Ironwood. Some projects are deprecating the C++ full node in favor of a Rust implementation and developing new wallets. Independent groups and funders are backing efforts to strengthen network security and sustainability as Zcash completes the post-Ironwood migration.