No Bitcoin soft fork needed for quantum resistance, StarkWare says

On August 26, 2026, Avihu Levy’s Quantum-Safe Bitcoin method transitioned from research to reality with the first quantum-safe transaction mined on the mainnet. The transaction demonstrates a functional solution for protecting Bitcoin holdings against future quantum computing threats before such computers widely exist, allowing coin holders to move assets into quantum-resistant storage.

“People have long assumed that protecting Bitcoin holdings from a quantum adversary would require changing the Bitcoin protocol,” said Levy, a researcher and General Manager of Applications at StarkWare, who designed the method in his own time with the help of engineer Tomer Giladi. This achievement bypasses the need for a soft fork, challenging previous assumptions about the only path to quantum resistance.

Avihu Levy’s QSB Method Secures Bitcoin on Mainnet

Bitcoin’s reliance on elliptic curve cryptography presents a long-term vulnerability; a successful quantum computer could compromise the private keys securing holdings. However, a recent demonstration showcases a method to move coins into quantum-resistant storage without altering the fundamental rules of the Bitcoin network. Levy, with the aid of StarkWare engineer Tomer Giladi, constructed a system that adds a second layer of security alongside existing cryptographic locks, relying on hash functions instead of elliptic curves.

Unlike elliptic curves, hash functions are not susceptible to being broken by Shor’s algorithm, a quantum algorithm posing a threat to current cryptographic systems. QSB achieves this by employing signature grinding, a technique allowing the creation of valid Bitcoin signatures without a private key. This process requires computational effort performed off-chain, before the transaction is broadcast to the network. The resulting transaction, while valid, utilizes a nonstandard format, currently necessitating a direct connection to a miner for inclusion in a block; MARA Slipstream facilitated this mining path for the initial demonstration.

While QSB does not inherently make all Bitcoin transactions quantum-safe, it provides a pathway for users to secure specific outputs, moving funds into an address protected by hash-based cryptography. “Avihu took this on after hours, as a passion project, and has now shown that Bitcoin has no expiration date,” said StarkWare CEO Eli Ben-Sasson.

“I still want Bitcoin to choose to do a soft fork and I expect we will get one. What today’s successful transaction offers Bitcoin is a reassurance that holdings can be protected before that happens.” QSB is most effective for securing funds before a public key has been revealed on the network, as an adversary could derive the private key during the brief window between transaction broadcast and mining.

The open-source implementation of QSB is available on GitHub, alongside the research paper detailing the method, allowing for further scrutiny and development within the Bitcoin community. While StarkWare’s own technology, based on ZK-STARKs, is inherently post-quantum secure, Levy deliberately designed QSB to function entirely within the existing Bitcoin framework, demonstrating a commitment to leveraging the network’s existing capabilities.

This currently costs around several hundred dollars and leverages the Binohash algorithm originally developed by BitVM creator Robin Linus. However, this approach is not retroactive; addresses with previously published public keys remain vulnerable until the funds are moved using QSB. Levy said, “Today shows otherwise.”