TL;DR
- StarkWare confirmed the first quantum-resistant Bitcoin transaction executed on mainnet, in block 964,199.
- The method combines single-use hash signatures with computational lookups, and does not require a protocol fork to function.
- The process costs between $150 and $200 in GPU compute and demands hours of processing, which limits it to emergency use.
Blockchain research company StarkWare confirmed that researcher Avihu Levy successfully executed the first quantum-resistant Bitcoin transaction on the network’s mainnet.
The transaction was confirmed in block 964,199 and consisted of spending a 10,000 satoshi output protected under the scheme known as Quantum Safe Bitcoin (QSB), developed by Levy himself. The block was mined by MARA Pool, which received the transaction outside the standard flow through its Slipstream service.
StarkWare’s QSB scheme combines single-use hash signatures with computational lookups that bind an authorization to a specific transaction. The goal is to prevent forgery even if a quantum computer manages to break the elliptic curve cryptography that Bitcoin currently uses. This demonstration succeeded in implementing Levy’s theoretical proposal within the network, without requiring changes to the protocol’s consensus rules.
StarkWare’s Solution Is Transitional and Meant for Emergencies
In March, researchers from Google estimated that a sufficiently powerful quantum computer could derive a Bitcoin private key in between nine and twelve minutes from the moment its public key becomes visible. That would leave an attack window open during the transaction confirmation period. Levy presented QSB as a last-resort measure for that scenario, not as a replacement for protocol-level protections.
StarkWare spokesperson Nathan Jeffay indicated that the completed transaction cost “a few hundred dollars”, with an estimate of between $150 and $200 in GPU compute, and that the process took several hours. Additionally, QSB transactions are classified as non-standard under the default relay policies of Bitcoin Core, which prevents ordinary nodes from propagating them before confirmation.
StarkWare CEO Eli Ben-Sasson stated that a soft fork should be implemented and that QSB could serve as a safety net while protocol-level protections are developed. Bitcoin developers are independently evaluating proposals such as BIP-360, a soft fork that would introduce a new Pay-to-Merkle-Root output type and eliminate the vulnerable spending path from Taproot.
