Starkware Mines Quantum-Safe Bitcoin Transaction on Mainnet

Starkware successfully mined a quantum‑resistant Bitcoin transaction on the mainnet on August 26, demonstrating an opt‑in protection method that does not require any changes to Bitcoin’s consensus rules.

How the QSB Transaction Was Executed

The transaction used the Quantum‑Safe Bitcoin (QSB) construction developed by Starkware researcher Avihu Levy. It spent a 10,000‑satoshi output and was mined through the MARA Foundation’s Slipstream service because its nonstandard format would not normally propagate through the public mempool.

Technical Approach

QSB replaces the elliptic‑curve signature with a hash‑based spending condition and employs a technique called signature grinding. Most of the computational work is performed off‑chain before broadcasting, requiring several hours of GPU processing and costing roughly $150‑$200.

Limitations and Future Outlook

While the test shows that individual funds can be protected without a protocol upgrade, QSB remains an optional solution. It cannot recover already exposed keys or protect funds that have not been moved into the QSB construction. Starkware’s CEO, Eli Ben‑Sasson, continues to advocate for a soft‑fork solution at the protocol level.

Industry Context

Bitcoin’s reliance on elliptic‑curve cryptography makes it theoretically vulnerable to future quantum computers running Shor’s algorithm. The QSB experiment provides a short‑term hedge, but broader consensus on a network‑wide quantum defense is still lacking.