Overview
- StarkWare published a mined transaction on Bitcoin mainnet that used Avihu Levy’s Quantum‑Safe Bitcoin (QSB) construction to add a hash‑based spending lock on funds, a demonstration completed on Aug. 26.
- QSB uses signature grinding and Lamport‑style, hash‑based checks that rely on RIPEMD‑160 preimage resistance instead of secp256k1 signatures, yielding roughly 118‑bit second‑preimage strength.
- Creating a QSB spend requires heavy off‑chain GPU work that can take hours and is estimated to cost about $75–$150 in cloud compute with some runs costing several hundred dollars.
- The mainnet transaction was nonstandard so it had to be submitted directly to a cooperating miner and was mined via MARA’s Slipstream service, which bypasses normal mempool relay rules.
- QSB does not make Bitcoin fully quantum‑safe because it does not cover Taproot, Lightning or coins whose public keys were already exposed, and developers call for independent review, repeated testing, wallet integration, and protocol proposals such as BIP‑360 and SHRINCS before any network‑wide migration can be attempted.