StarkWare researchers have published what they claim is the first way to make Bitcoin transactions quantum secure on today’s live networks without making any changes to the Bitcoin protocol. However, the scheme costs up to $200 per transaction and is designed as an emergency measure rather than a permanent solution.
In a paper published this week, StarkWare researcher Avihu Levy introduced Quantum Safe Bitcoin (QSB). QSB is a scheme that aims to enable quantum-resistant transactions without requiring changes to the Bitcoin protocol by replacing signature-based security assumptions with hash-based proofs within its design.
Hash-based designs can withstand quantum attacks that can break today’s cryptography, but they shift the burden from consensus to computation, requiring a significant amount of off-chain GPU work for each transaction.
Think of a traditional digital signature as a handwritten signature on a check that proves you authorized a transaction using a private key that someone else can check against your public key.
In Bitcoin, these digital signatures are called ECDSA signatures. While these are secure against today’s computers, a sufficiently powerful future quantum computer could theoretically derive the private key from the public key and compromise funds.
QSB addresses this flaw by redesigning the system around a different type of encryption, including hash-based proofs, similar to tamper-proof fingerprints, where a unique mathematical digest of the data is created, rather than relying solely on signatures. This is said to be extremely difficult to counterfeit or subvert, even with powerful computers.
QSB works perfectly within Bitcoin’s existing consensus rules for legacy transactions. No soft forks (software upgrades), minor signaling, or activation timelines are required. This is in sharp contrast to BIP-360, a quantum-resistant proposal that was integrated into Bitcoin’s official improvement proposal repository in February but has not been implemented by Bitcoin Core and faces years of governance delays.
The proposal builds on an earlier idea known as Binohash, which added an extra layer of computational work to secure Bitcoin transactions. The problem is that it depends on the type of encryption the quantum computer is expected to crack. In practice, this means that protection is lost in a quantum scenario. An attacker could completely bypass the system’s core security checks and disable its functionality.
additional cost
However, hash-based solutions imply very expensive transactions.
Generating a valid transaction requires searching through billions of candidates, a process that Levy estimates costs between $75 and $200 using a commodity cloud GPU. Currently, the cost of sending a Bitcoin transaction through the blockchain is approximately 33 cents.
There are also practical hurdles to this system. QSB transactions are not moved through Bitcoin’s regular blockchain like regular payments. Instead, users will have to send them directly to the miners they want to process.
It also doesn’t work with faster, cheaper layers like the Lightning Network, and is much more complex to create. Generating transactions requires not only signing and sending them from your wallet, but also outsourcing a large amount of computation to external hardware.
Levy described this plan as a “last resort” rather than a replacement for protocol-level upgrades. Proposals such as BIP-360, which aim to introduce quantum-resistant signature schemes via soft forks, remain a more scalable long-term solution, but could take several years to enable.
The startup schedule for BIP-360 is unknown. Polymarket bettors are pricing in that it is unlikely to happen this year, and there is little reason for any urgency in Bitcoin’s governance history. Taproot took about seven and a half years from concept to development. Once again, a mature quantum computer that can crack the codes that protect networks will not arrive tomorrow.
Instead, QSB offers something different. That’s how you can survive the quantum break using today’s rules, if your users are willing to pay.
