CoinShares: Quantum Threat to Bitcoin Manageable

CoinShares has published a guide that assesses the risk quantum computing poses to Bitcoin. The report concludes the threat is real but manageable and places machines capable of breaking Bitcoin’s signature scheme roughly 10 to 15 years in the future.

The guide explains that attacking Bitcoin’s current signature layer, which uses ECDSA, would require quantum computers with millions of qubits. CoinShares contrasts that requirement with Google’s Willow system, which operates at about 105 qubits, and notes no existing device can perform the described attack.

CoinShares estimates about 10,200 BTC stored in legacy pay-to-public-key (P2PK) addresses are immediately exposed because those addresses reveal public keys on-chain. That number is a small portion of roughly 4 million BTC held in older address formats. Most modern address types reveal public keys only when funds are spent, which limits immediate exposure. The guide states vulnerable coins can be moved to quantum-resistant address types without a Bitcoin hard fork.

The report outlines technical mitigations. Bitcoin’s Proof-of-Work consensus and roughly 10-minute block interval create a time constraint for an attacker trying to derive private keys and broadcast transactions before a legitimate user can act. The guide notes that timing constraint is not present in many Proof-of-Stake designs.

On standards and development, CoinShares records that the National Institute of Standards and Technology finalized ML-KEM and ML-DSA in 2024 and that Bitcoin’s open-source developer community is working on address formats that use post-quantum algorithms.

The guide highlights that many financial and government systems continue to rely on RSA-2048 or elliptic-curve cryptography and often lack the flexibility to update quickly. It is presented as a resource for advisors, offering a framework to assess short- and long-term exposure, steps for voluntary migration of vulnerable coins, and recommended monitoring of address types and developer progress as part of routine risk management for long-term holders.