Zcash seals $1.7 billion shielded pool as Ironwood upgrade activates
Zcash has activated the Ironwood upgrade, which migrates users to a new shielded pool to address a long-standing security vulnerability in the previous Orchard pool. The upgrade utilizes a 'turnstile' mechanism to prevent the circulation of potentially counterfeit coins created during the period the bug was active.
Why it matters
This move highlights the critical challenges of maintaining privacy-preserving cryptographic protocols and the importance of robust accounting mechanisms in decentralized finance.
Ironwood, formally known as NU6.3, retired the previous pool known as Orchard, which holds about 3.66 million ZEC, worth roughly $1.7 billion at current prices.
Ironwood held zero ZEC at activation, trackers showed . Every coin has to be moved across by its owner, and the only route out of Orchard is a turnstile — an accounting rule at the pool's boundary that caps total withdrawals at the amount verifiably deposited.
Shielded pools are the private side of Zcash, where the amounts of coins and participants are hidden. A zero-knowledge proof provides evidence that the amount deposited is reflected publicly.
On May 29, Shielded Labs researcher Taylor Hornby found that Orchard's proof circuit contained a bug that would let an attacker mint counterfeit ZEC, leaving no onchain trace. The flaw had been live since Orchard launched in May 2022.
Get smarter about the news
Sign up free for a feed built around what you actually care about, Dive Deeper research on any story, and the full text of every article.
Create free accountAlready have an account? Sign in