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Zcash activates Ironwood as Orchard turns exit-only after flaw discovery

Zcash activates Ironwood as Orchard turns exit-only after flaw discovery

NU6.3 closed Orchard to new shielded activity, opened a replacement pool, and began migration as more than 40,000 ZEC moved to Ironwood while about 3.6 million ZEC remained in Orchard.

ZEC

Fact Check
The Crypto Times article confirms every element of the claim: activation of Ironwood (NU6.3) on July 28, 2026 at block 3,428,143, creation of a new shielded pool, freezing/restriction of the old Orchard pool, a public-accounting turnstile, and origin in a critical soundness flaw that raised fears of undetectable counterfeiting. TechTimes and BitcoinFoundation independently confirm the identical block height (3,428,143) and July 28 date. With event_time July 28 and current date July 27, the 'tomorrow' framing is accurate. Multiple independent sources agree with no conflicting evidence.
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Summary

Zcash activated its Ironwood network upgrade at block 3,428,143 through NU6.3 on July 28, placing Orchard into permanent exit-only mode and opening a replacement shielded pool after a critical flaw in Orchard’s zero-knowledge circuit raised the theoretical risk of undetectable counterfeit ZEC. More than 40,000 ZEC had already moved into Ironwood while roughly 3.6 million ZEC remained in Orchard awaiting migration. Ironwood uses a turnstile that limits withdrawals from Orchard to the amount verifiably deposited, preventing any hypothetical excess coins from entering the new pool, and researchers said a machine-checked Lean proof spanning more than 2,700 theorems formally verified Ironwood’s balance integrity under stated cryptographic assumptions. ZEC briefly fell about 9% to around $460 after the upgrade before recovering to roughly $475.

Terms & Concepts
  • turnstile: A protocol checkpoint that limits how much ZEC can leave Orchard to the amount that can be shown to have entered it.
  • formal verification: A mathematical process used to prove that software or protocol logic satisfies specific properties.
  • balance integrity: Assurance that a shielded pool cannot create or pay out more value than has legitimately entered it under stated assumptions.