Researcher Avihu Levy from StarkWare has unveiled what he claims is the inaugural method of securing bitcoin transactions against quantum attacks on today’s live network, all without modifying the Bitcoin protocol. However, this solution incurs a significant transaction fee of up to $200 and serves as an emergency measure rather than a long-term fix.
In his latest paper, Levy introduces Quantum Safe Bitcoin (QSB), which allows for quantum-resistant transactions by substituting signature-based security with hash-based proofs within its framework. This approach withstands the type of quantum attacks that threaten current cryptographic methods, shifting focus from consensus to computation and necessitating intensive GPU work off-chain for each transaction.
Traditional digital signatures in Bitcoin, known as ECDSA signatures, function like a handwritten signature on a cheque, verifying authorization through a secret key cross-checked with a public one. While these are secure against present-day computers, future quantum computers could theoretically deduce the secret key from its public counterpart and potentially compromise funds.
QSB addresses this vulnerability by employing hash-based proofs, akin to a tamper-proof fingerprint that uses a unique mathematical digest of data rather than relying solely on signatures. This is considered highly resistant to forgery or reversal, even by powerful quantum computers.
The QSB mechanism operates within Bitcoin’s existing consensus rules for legacy transactions and requires no soft fork, miner signaling, or activation timeline—a stark departure from BIP-360, the official quantum-resistance proposal that remains without a Bitcoin Core implementation and is bogged down by governance delays. This builds upon the concept of Binohash, which added computational work to secure transactions but relies on cryptography vulnerable to quantum attacks.
The hash-based method leads to costly transactions. Creating a valid transaction necessitates sifting through billions of possibilities, with Levy estimating costs between $75 and $200 using commodity cloud GPUs—a stark contrast to the current 33-cent blockchain transaction fee.
Practically speaking, QSB transactions do not traverse Bitcoin’s standard blockchain like typical payments but are sent directly to miners willing to process them. They are incompatible with faster, cheaper layers such as the Lightning Network and require complex creation processes that involve outsourcing heavy computation to external hardware instead of simply signing and sending from a wallet.
Levy regards QSB as an emergency measure rather than a substitute for protocol-level upgrades. Proposals like BIP-360, which propose quantum-resistant signature schemes through soft forks, are seen as more scalable long-term solutions but face years of potential delays before activation. The uncertain timeline for BIP-360 is underscored by Polymarket bettors who assign it low odds of occurring this year and Bitcoin’s historical governance pace—illustrated by the roughly seven-and-a-half-year journey from concept to deployment for Taproot.
While mature quantum computers capable of breaking current encryption are not imminent, QSB presents an alternative: enabling survival under a quantum threat using existing rules, contingent on users’ willingness to bear the costs.