First Quantum-Safe Bitcoin Transaction Executed Without a Fork

Are fund managers handling bitcoin right to be concerned about quantum computing risks?

The quick reply is affirmative, though there is still time to get ready and solutions are emerging.

One such solution is post-quantum bitcoin transactions on the mainnet, the first of which occurred this week thanks to the Starknet Foundation.

JUST IN: The first post-quantum resistant Bitcoin transaction was mined today.

"It required no soft forks. It required no hard forks. It required no core protocol upgrades. And it's live today."

— Bitcoin Magazine (@BitcoinMagazine) August 27, 2026

Damian Chen, VP of growth at the Starknet Foundation, speaking at Bitcoin Asia in Hong Kong on Thursday, showed how funds at risk from future quantum attacks can be protected without a network-wide fork using the company's new solution.

“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.”

The transaction was carried out with a method devised by StarkWare researcher Avihu Levy. Here is how it functions: Bitcoin transactions wait briefly in a public queue prior to confirmation. In that interval, they reveal cryptographic material that a powerful enough quantum machine could exploit to forge a signature and steal the funds before the transaction gets confirmed.

Instead of accepting the first valid signature, Levy's technique produces millions of signature candidates until it locates one with a particular structural property that does not disclose that vulnerable material during its stay in the mempool.

This process, called 'signature grinding,' is intentionally costly in computation—a single transaction requires hours to generate—but that expense is precisely what renders it immune to quantum-based shortcuts.

Promoting quantum-safe bitcoin transactions—referred to as 'QSB'—to institutional clients, Chen stated that even if attackers possess a fund's private keys, they would be unable to execute a fraudulent transfer.

“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,” he said.

It should be noted that standard bitcoin nodes do not currently recognize this non-standard transaction format, so it could not enter the public mempool and had to be delivered directly to a miner willing to accept it—mining firm MARA's Slipstream service was the one that mined this QSB transaction.

Quantum researchers have cautioned that a point will arrive when bitcoin's software—which supports the largest and most powerful computer network globally—must be updated to handle quantum computing.

Although some crypto venture capital firms have called for action, leading bitcoin developers contend that many current quantum computers possess restricted capabilities and have only shown trivial computations.

Nevertheless, they have observed that progress could occur without warning—similar to advances in artificial intelligence—and have begun working on some solutions.

Chen added: “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?”