A StarkWare researcher has published what he says is the first method to make bitcoin transactions quantum-secure on the live network today without 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, or QSB, 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.
The hash-based design survives the kind of quantum attacks that would break today’s cryptography, but shifts the burden from consensus to computation, requiring heavy off-chain GPU work for each transaction.
Think of traditional digital signatures as a handwritten signature on a check that proves you authorized a transaction using a secret key that others can cross-check with a public key.
In Bitcoin, these digital signatures are called ECDSA signatures. They are secure against today’s computers, but a sufficiently powerful future quantum computer could in theory derive the secret key from a public key and potentially compromise funds.
QSB addresses this flaw by redesigning the system around a different form of cryptography involving hash-based proofs, more akin to a tamper-proof fingerprint, where instead of relying on signature alone, a unique mathematical digest of data is created. This is said to be extremely difficult to fake or reverse, even for powerful computers.
QSB operates entirely within Bitcoin’s existing consensus rules for legacy transactions. It requires no soft fork (software upgrade), no miner signaling and no activation timeline. This is a stark contrast to BIP-360, the quantum resistance proposal that was merged into Bitcoin’s official improvement proposal repository in February, but has no Bitcoin Core implementation 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 a form of cryptography that quantum computers are expected to break. In practice, this means that the protection disappears in a quantum scenario. An attacker can completely bypass the system’s core security checks, rendering it ineffective.
Additional costs
However, the hash-based solution means extremely expensive transactions.
Generating a valid transaction requires searching through billions of possible candidates, a process Levy estimates will cost between $75 and $200 using commodity cloud GPUs. Currently, the cost of sending a bitcoin transaction through the blockchain is around 33 cents.
The system also comes with practical obstacles. QSB transactions would not move through Bitcoin’s normal blockchain like typical payments. Instead, users will likely have to send them directly to miners willing to process them.
They also don’t work with faster, cheaper layers like the Lightning Network, and they’re far more complicated to create. Generating a transaction would require outsourcing heavy computation to external hardware instead of simply signing and sending from a wallet.
Levy describes the scheme as a “last resort” measure, not a substitute for protocol-level upgrades. Proposals like BIP-360, which aims to introduce quantum-resistant signature schemes through a soft fork, remain the more scalable long-term solution, but could take years to activate.
BIP-360’s activation timeline is uncertain. Polymarket bettors are pricing low odds of that happening this year, and Bitcoin’s governance history suggests no rush — Taproot took about seven and a half years from idea to implementation. Then again, mature quantum computers capable of breaking the encryption that secures the network won’t arrive tomorrow either.
Instead, QSB offers something else: a way to survive a quantum breach using today’s rules, if users are willing to pay for it.
