Zcash rolls out Ironwood with a math receipt thicker than your portfolio 📜

Project Tachyon researchers have completed a formal verification of Zcash's Ironwood shielded pool, publishing a machine-checked proof in the Lean programming language that the network's new shielded pool contains no undetectable counterfeiting bugs under its stated cryptographic assumptions. The proof covers the components required for the security property known as balance integrity, including Ironwood's zero-knowledge proof system, circuit rules and ledger-level accounting, though it does not address the pool's separate privacy guarantees.

According to Project Tachyon, the proof comprises over 2,700 theorems and was produced by three teams of researchers and cryptographers working for more than a month. The effort establishes that the shielded pool cannot pay out more value than has publicly entered it, addressing the type of supply-integrity failure that prompted the upgrade.

Ironwood was introduced through Zcash's NU6.3 upgrade following the discovery of a vulnerability in the Orchard shielded pool that could theoretically have enabled undetectable ZEC counterfeiting. Zcash developers said they found no evidence that the flaw had been exploited, and the new pool was designed to restore confidence in ZEC supply integrity.

Funds migrating from Orchard are required to pass through a public accounting checkpoint known as a turnstile, which is designed to prevent any hypothetical excess coins from entering Ironwood. As funds leave Orchard, the migration process may also yield increasing evidence about whether the older pool was exploited, giving researchers a way to assess historical activity as the transition progresses.