Coinbase executive explains Bitcoin quantum risk and the long-term threat to network security

Concerns about future advances in cryptography are reshaping how analysts think about long-term Bitcoin security, with Bitcoin quantum risk now on the radar of major exchanges.

Quantum computing and Bitcoin main risks

Advances in quantum computing could eventually challenge more than Bitcoin private key security, raising questions about the network’s economic and security foundations. However, current hardware is still far from breaking Bitcoin‘s defenses, so these are long-term risks rather than immediate threats.

The primary danger is tied to a hypothetical future “Q-day,” when quantum machines might run algorithms such as Shor’s and Grover’s at sufficient scale. At that point, core components of Bitcoin’s cryptography could be undermined. Moreover, this scenario would affect both transaction security and mining.

Bitcoin currently relies on two key primitives: ECDSA, which secures transaction signatures and establishes ownership, and SHA-256, which supports proof-of-work mining and protects blockchain integrity. That means quantum systems could theoretically mount two distinct classes of attacks, targeting signatures and hashing.

Signature attacks and exposed Bitcoin addresses

On the signature side, quantum-capable systems could weaken the cryptographic shields that protect private keys, opening the door to unauthorized spending from vulnerable addresses. This risk splits into two dimensions: long-range attacks against outputs whose public keys are already on-chain, and short-range attacks attempting to front-run spends once keys appear in the mempool.

Coinbase estimates that about 6.51 million Bitcoin, or roughly 32.7% of the total supply at block 900,000, may be exposed to long-range quantum attacks. This figure highlights how past behavior such as address reuse vulnerability and certain script types can increase risk across the network.

The long-range threat is linked to outputs that reveal public keys directly on-chain. These include Pay-to-Public-Key (P2PK), bare multisignature (P2MS), and Taproot (P2TR) formats. Early Bitcoin holdings, often associated with the Satoshi era, represent a notable share of the older P2PK outputs and therefore a meaningful cluster of potential targets.

Every output becomes vulnerable to a short-range attack at the exact moment of spending, when the public key is revealed before confirmation. That said, the probability of a successful attack with current quantum hardware is still very low. Even so, this dynamic underscores why the industry is increasingly focused on migrating to quantum resistant signatures.

Economic impact and the risk to mining

Beyond signature theft, the second major concern involves Bitcoin’s mining economics and consensus security. Quantum-enabled devices might eventually gain efficiency advantages in proof-of-work, disrupting the current balance between miners. However, researchers still see this as a secondary issue compared to key compromise.

In theory, highly optimized quantum enabled mining could alter the distribution of hash power and introduce new centralization pressures. However, scaling constraints and the early stage of practical quantum hardware keep this scenario firmly in the future. For now, signature migration remains the core technical and policy priority.

Some experts argue that any credible path to bitcoin quantum risk will likely begin with attacks on exposed public keys rather than on SHA-256 mining. Moreover, changes to mining algorithms are technically easier to coordinate than a wholesale shift in how users secure their coins, which is why encryption and signatures are at the center of current debates.

Post-quantum cryptography options under review

To prepare for these scenarios, developers and researchers are studying post-quantum cryptography and other defensive techniques. The main long-term mitigation strategy is to integrate quantum-resistant signature schemes directly into the Bitcoin protocol. However, this transition will require years of research, testing, and consensus building.

The US National Institute of Standards and Technology (NIST) has been running a multi-year process to select post quantum cryptography algorithms for standardization. Its shortlist currently includes CRYSTALS-Dilithium, SPHINCS+, and FALCON, each offering different trade-offs in terms of security, size, and performance.

These NIST candidates provide a reference point for what next-generation signatures in Bitcoin could look like. However, there are practical hurdles. Many quantum-safe schemes have larger signatures and slower verification, which would impact blockspace usage, fee markets, and node performance. Moreover, wallet software and infrastructure providers would have to retool their systems.

Migration timelines and potential upgrade paths

Research now outlines two broad migration paths, depending on how fast quantum computing progresses. A rapid breakthrough would demand an emergency plan that could be executed in roughly two years, prioritizing speed and backward compatibility. That said, such a scenario assumes strong coordination across miners, node operators, and wallets.

If progress remains gradual, a more measured approach could unfold over as long as seven years. In that case, Bitcoin might integrate quantum-safe signatures through a soft fork, allowing users to opt in over time. This path would give developers more room to refine designs and test new schemes under real-world conditions.

Technical proposals such as BIP-360, BIP-347, and Hourglass are already exploring how to manage key rotation, migration, and script upgrades in a quantum-aware way. Moreover, these efforts aim to minimize disruption while ensuring vulnerable outputs are moved into safer encodings before any credible quantum attack materializes.

Operational best practices for Bitcoin holders

Until protocol-level changes arrive, best practices can already reduce exposure. Avoiding address reuse, regularly moving vulnerable UTXOs to fresh destinations, and limiting per-address balances all help mitigate concentration risk. However, these habits must be widely adopted to meaningfully lower systemic vulnerability.

Institutions and service providers are also encouraged to develop client-facing materials that standardize quantum-aware operations. Clear guidance on how to manage older outputs, script types, and migration scheduling could help users prepare long before any emergency. Moreover, the fact that many vulnerable scripts are not heavily used in modern production environments is viewed as a modest advantage.

While these steps cannot eliminate threats rooted in fundamental mathematics, they can buy time. They also help ensure that if a migration to quantum-safe schemes becomes urgent, fewer coins will be locked in legacy scripts that are hard to move or coordinate.

Industry sentiment and future outlook

Across the industry, quantum computing is generally not regarded as an imminent danger to Bitcoin security. Most experts see today’s devices as far too weak to threaten ECDSA or SHA-256 at scale. However, opinions diverge on how quickly the landscape might change.

Some researchers and project teams have warned that practical compromise could arrive within a few years under favorable assumptions for hardware progress. Various initiatives have even suggested possible dates when bitcoin private key risk might become material. Moreover, continued investment in quantum research keeps the topic high on the agenda for security-minded developers.

For now, Bitcoin’s defenses remain robust, but planning for a post-quantum world is underway across standards bodies, protocol research, and wallet engineering. The combination of proactive migration strategies, better user practices, and ongoing innovation in quantum-safe cryptography will likely determine how resilient the network proves to be in the face of future breakthroughs.

In summary, quantum advances pose long-term challenges to Bitcoin’s signatures and mining, but measured preparation, protocol research, and improved operational hygiene give the ecosystem a clear path to adapt over time.