Quantum-Safe Bitcoin (QSB) Proposal Sidesteps a Fork, Costs Compute

| decrypt.co
StarkWare researcher Avihu Mordechai Levy proposed “Quantum-Safe Bitcoin” (QSB), a transaction design intended to protect Bitcoin’s elliptic-curve signatures from future quantum threats without changing Bitcoin consensus or requiring a soft fork. Quantum-Safe Bitcoin swaps current EC signatures for hash-based cryptography using Lamport signatures, while fitting within Bitcoin’s tight script limits (201 opcodes, 10,000 bytes). Traders should treat this as a last-resort workaround, not a scalable upgrade. It requires solving a cryptographic puzzle before broadcasting. Levy estimates about 70 trillion attempts, with users doing off-chain computation (potentially GPU-based) costing a few hundred dollars per transaction. A “transaction pinning” mechanism makes modification attempts force the puzzle to be solved again. Security trade-offs remain: Shor’s algorithm resistance is targeted, but Grover’s algorithm could still provide quantum attackers a quadratic speedup. Levy also stresses the proposal is not complete and calls for continued protocol-level post-quantum work, including references like BIP-360. The quantum risk is still theoretical, but major firms (e.g., Google, Cloudflare) have publicly discussed post-quantum migration timelines around 2029. Overall, Quantum-Safe Bitcoin is an important research signal for Bitcoin security, but it does not directly change live transaction validation today.
Neutral
This is a research proposal, not a protocol change. Quantum-Safe Bitcoin sidesteps a soft fork and does not alter how live Bitcoin blocks validate today, so there is no immediate catalyst for BTC price. The compute-heavy, last-resort nature (trillion-scale attempts and hundreds of dollars per transfer) limits practical adoption, and the security claims are not universally settled given potential Grover-related speedups and broader critiques (e.g., dormant keys). In the short term, traders are unlikely to reprice BTC risk materially based on a theoretical mitigation path; over the longer term, it may support a gradual “security readiness” narrative around post-quantum migrations, but that is not expected to drive near-term market instability.