StarkWare's Avihu Levy Proposes Quantum-Safe Bitcoin Transactions Without a Soft Fork

Quantum-proof Bitcoin transactions without changing the protocol

Avihu Levy, Chief Product Officer at StarkWare, has introduced a concept called Quantum Safe Bitcoin (QSB). The scheme aims to make Bitcoin transactions resistant to quantum computer attacks while operating entirely within the existing Bitcoin Script framework — no soft fork required.

«Quantum-Safe Bitcoin Transactions Without Softforks» — Avihu Levy ✨🐺 (@avihu28), original post

Currently, standard Bitcoin transactions rely on the ECDSA algorithm, which is built on elliptic curve mathematics. This cryptographic approach is considered vulnerable to quantum computing, particularly Shor's algorithm, which can theoretically break such encryption systems.

How QSB works

Instead of elliptic curve cryptography, QSB employs Binohash — a one-time signature mechanism embedded directly into the existing Bitcoin Script language. Binohash ensures transaction integrity through a Proof-of-Work mechanism.

However, Binohash itself is not immune to quantum attacks. QSB addresses this vulnerability by introducing a "hash-to-signature" approach. This method requires the sender to solve a hash-based computational challenge rather than one based on elliptic curve math.

According to Levy, even the most powerful quantum computer would be powerless against this defense. He explained that the challenge relies solely on the preimage resistance of RIPEMD-160 and makes no assumptions about elliptic curves, making it fully secure against Shor's algorithm.

Why this matters

The quantum threat to Bitcoin has been a recurring discussion for years, but most proposed solutions — such as BIP-360 — require protocol-level changes and broad community consensus. QSB takes a fundamentally different approach: it works within Bitcoin's current scripting capabilities and needs no soft fork. This could make it significantly faster to deploy if a quantum threat materializes suddenly.

The proposal also highlights a growing trend among developers to explore emergency-ready solutions that don't depend on the typically slow Bitcoin governance process.

Cost and practical limitations

Levy estimated the cost of a single QSB transaction at $75–150 based on current cloud computing prices. By comparison, the average Bitcoin transaction fee sits around $0.3. Due to this steep cost difference, the researcher himself described the tool as a "measure of last resort."

That said, Levy considered the price "practically acceptable" because the computations can be distributed across multiple GPUs in parallel.

Key obstacles to widespread adoption include:

• Script and code size limits within the Bitcoin network
• Lack of support for certain features, including Lightning Network micropayments
• The experimental nature of the initiative

An emergency tool, not a permanent fix

Despite being compatible with Bitcoin's base consensus rules, QSB remains an experimental project at this stage. Levy emphasized that if the quantum threat proves real, the community must continue searching for the most efficient, user-friendly, and purpose-built solution for Bitcoin — implemented through proper protocol-level changes.

Earlier in April, Bitcoin developer Olaoluwa Osuntokun introduced a prototype tool designed to protect Bitcoin wallets from potential quantum attacks, signaling growing urgency around quantum preparedness in the Bitcoin ecosystem.