StarkWare researcher Avihu Levy has tested an experimental quantum-resistant transaction on the Bitcoin mainnet. StarkWare described it as the first transaction of its kind. It was confirmed on Wednesday in Bitcoin block 964,199, and onchain data showed that the test spent a 10,000-satoshi output protected by Levy’s Quantum Safe Bitcoin, or QSB, scheme. The technical execution fell outside Bitcoin’s usual transaction-relay process because of its nonstandard structure. MARA Pool mined the block after receiving the transaction directly through its Slipstream service. Levy’s paper and code repository say QSB transactions are nonstandard under Bitcoin Core’s default relay policies. Ordinary nodes therefore would not propagate the transaction before confirmation, so it had to be submitted directly through Slipstream. Levy’s QSB scheme addresses the risk that quantum computers could break the elliptic-curve cryptography that currently secures Bitcoin. It combines hash-based one-time signatures with computational searches that bind an authorization to a particular transaction. The construction is intended to prevent forgery even if a quantum computer can break the elliptic-curve cryptography used by Bitcoin. The vulnerability behind this research was discussed earlier this year. In March, Google researchers estimated that a sufficiently capable quantum computer could theoretically derive a Bitcoin private key nine to 12 minutes after its public key becomes visible. Google said that could allow an attacker to replace a pending transaction during Bitcoin’s confirmation window. Levy introduced QSB in April, describing it as a last-resort measure rather than a replacement for protocol-level protections. The mainnet test moved his proposal from theory to an onchain demonstration. It shows that Bitcoin’s existing consensus rules can accommodate one form of quantum-resistant spending without a protocol change. QSB is currently costly and time-consuming. StarkWare said the process took hours of computation. StarkWare spokesperson Nathan Jeffay said the completed transaction cost “low hundreds of dollars,” estimating the expense at about $150 to $200. When Levy proposed the system, he estimated that generating a transaction would require $75 to $150 in GPU computation. QSB applies to individual Bitcoin transactions and does not upgrade cryptography across the entire network. StarkWare CEO Eli Ben-Sasson said, “A soft fork should happen, and I believe it will,” adding that QSB provides a safety net while protocol-level protections are developed. Bitcoin developers are separately considering proposals including BIP-360, a proposed soft fork. It would introduce a Pay-to-Merkle-Root output type while removing Taproot’s quantum-vulnerable key-path spend. A $150 to $200 cost and direct submission through a mining pool make this test unsuitable for everyday Bitcoin transfers. For people in Somalia and the diaspora, it remains a technical experiment rather than something readily used through ordinary mobile wallets, while wider protections are still being considered.