Bitcoin Sees First Quantum-Proof Mainnet Transaction

The Bitcoin mainnet has successfully processed an experimental transaction designed to withstand attacks from future quantum computers. Utilizing existing consensus rules, the transfer bypasses the need for immediate network upgrades, demonstrating a functional pathway for securing vulnerable digital assets against theoretical computing threats.

Speaking at the Bitcoin Asia conference in Hong Kong, Damian Chen, VP of growth at the Starknet Foundation, showcased the milestone to attendees.

“This is a monumental moment,” Chen said. “This is the first post-quantum-resistant Bitcoin transaction on bitcoin mainnet today. It required no soft forks; it required no hard forks; it required no core protocol upgrades, and it’s live today.”

Signature Grinding and Security

The method, spearheaded by StarkWare researcher Avihu Levy, targets the brief confirmation window when a standard transaction sits in the public mempool queue. During this period, cryptographic data is exposed, potentially allowing an advanced quantum machine to forge a signature and siphon assets before the block is finalized. To counter this, Levy’s design avoids the first valid signature and instead generates millions of candidates to isolate one with a specific structural property that safely obscures vulnerable material.

This off-chain computational effort, known as signature grinding, is highly resource-intensive. According to StarkWare spokesperson Nathan Jeffay, as reported by Finanzen, generating the protective transaction required hours of specialized computing time and cost roughly $150 to $200 in hardware overhead. Because the resulting non-standard transaction format is rejected by standard node operators, it had to be routed directly to mining firm MARA. On-chain data cited by Finanzen shows that MARA's Slipstream service successfully mined the 10,000-satoshi transfer directly into Bitcoin block 964,199.

A Costly Stopgap

By utilizing a distinct mathematical framework, the Quantum Safe Bitcoin framework neutralizes the advantage a quantum attacker might possess.

“QSB introduces a new hash authorization, and so an attacker with a sufficiently capable computer, even if they have your exposed public key, even if they derive your private key from your public key, even if they try to use that to authorize a spend to move your coins out of your wallet, those things are not enough for them to do so,” Chen said.

Despite the technical achievement, developers and infrastructure providers caution against viewing this demonstration as a permanent fix. Finanzen noted that Levy himself has characterized the computationally heavy method as a last-resort emergency measure for individuals, rather than a scalable replacement for protocol-level protections. Similarly, Isabela Foxen, head of the MARA Foundation, emphasized in a statement to AMBCrypto that relying on direct-to-miner services like Slipstream is not a sustainable, long-term solution for broader network resilience.

Ultimately, while core developers debate the timeline of viable quantum threats, proponents argue that preparation remains necessary before hardware advancements arrive.

“The question to me has never been when will quantum arrive. We all know quantum will arrive at one stage, but the question to me has always been, how long will it take for you to be ready when quantum does arrive?” Chen added.