StarkWare mines first quantum-safe Bitcoin transaction on mainnet

The transaction is a demonstration of a spending construction, not a protocol upgrade. The onchain record proves that the transaction was included in the block; the claim that the construction resists a future quantum computer comes from StarkWare and researcher Avihu Levy, who designed QSB.

A new lock inside old rules

QSB adds a hash-based lock alongside Bitcoin's ordinary elliptic-curve authorization. The method uses offchain signature grinding to find a transaction whose hash fits the structure Bitcoin Script will accept, then relies on hash preimage resistance rather than the difficulty of breaking an elliptic curve.

The completed spend cost several hundred dollars and hours of computation, according to the project's account. Because the transaction uses a nonstandard format, ordinary nodes do not relay it through the normal mempool. MARA's Slipstream service provided the direct path to a miner.

What the transaction does not prove

StarkWare explicitly says QSB does not make Bitcoin itself quantum-safe. It protects coins only after they are moved into the special output, does not retrofit protection onto ordinary ECDSA- or Schnorr-secured holdings and does not help an address whose public key was already exposed before the protective spend.

The full transaction is visible at Mempool.space, while the method's code and paper are public in the QSB repository. The result is an important mainnet demonstration and a possible safety net, not evidence that Bitcoin holders need to move funds today or that a quantum attack is underway.