StarkWare researcher Avihu Levy executed a quantum-resistant Bitcoin transaction on the mainnet, marking the first onchain demonstration of the approach. The transaction, confirmed in block 964,199, spent a 10,000-satoshi output protected by Levy’s Quantum Safe Bitcoin (QSB) scheme. MARA Pool mined the block after receiving the transaction via its Slipstream service.
The QSB method combines hash-based one-time signatures with computational searches to bind authorization to a specific transaction, preventing forgery even if quantum computers compromise Bitcoin’s elliptic-curve cryptography. StarkWare noted the test validates that Bitcoin’s existing consensus rules can support quantum-resistant spending without requiring protocol changes.
The transaction’s computational cost was estimated at $150 to $200, with StarkWare describing the process as taking hours of GPU computation. StarkWare spokesperson Nathan Jeffay characterized the expense as "low hundreds of dollars." The method remains nonstandard under Bitcoin Core’s default relay policies, meaning ordinary nodes would not propagate such transactions before confirmation, necessitating direct submission through MARA’s Slipstream service.
StarkWare CEO Eli Ben-Sasson emphasized that QSB serves as a temporary safeguard while protocol-level protections are developed. He stated a soft fork should ultimately occur to address quantum vulnerabilities. Bitcoin developers are separately evaluating proposals like BIP-360, which would introduce a Pay-to-Merkle-Root output type while removing Taproot’s quantum-vulnerable key-path spend.
Google researchers previously estimated that a sufficiently powerful quantum computer could theoretically derive a Bitcoin private key within nine to 12 minutes of its public key becoming visible, potentially enabling transaction replacement during Bitcoin’s confirmation window. Levy introduced QSB in April as a last-resort measure rather than a replacement for foundational protocol upgrades.
