Why Quantum Computing Isn’t the Immediate Bitcoin Threat Many Assume

Concerns that quantum computing could one day break Bitcoin’s cryptography have resurfaced. Yet, a new report by CoinShares argues that the quantum risks remain distant, with only a fraction of Bitcoin’s supply potentially vulnerable. The report frames quantum computing as a long-term engineering challenge. It argues that Bitcoin has ample time to adapt well before quantum machines reach a cryptographically relevant scale. The Quantum Threat Assessment For Bitcoin In the report titled “Quantum Vulnerability in Bitcoin: A Manageable Risk,” CoinShares’ Bitcoin Research Lead Christopher Bendiksen explained that Bitcoin relies on elliptic-curve cryptography to secure transactions. In theory, a sufficiently powerful quantum computer could use Shor’s algorithm to derive private keys from public keys. This could enable unauthorized spending. However, Bendiksen noted that such an attack would require quantum machines with millions of stable, error-corrected qubits. This is far beyond today’s capabilities. “Breaking secp256k1 within a practical amount of time (<1 year) needs 10-100,000 times the current number of logical qubits; relevant quantum tech at least 10 years off. Long-term attacks can take place over years—could become feasible within a decade; short-term (mempool attacks) need <10-min computations—infeasible in anything but the very long term (decades),” the report read. The report also examined the scope of Bitcoin’s real exposure. According to Bendiksen, only about 1.6 million BTC, roughly 8% of the total supply, resides in legacy Pay-to-Public-Key (P2PK) addresses where public keys are already exposed. However, the true practical risk is significantly smaller. Of that amount, the report estimated that only around 10,200 BTC could plausibly be targeted in a way that would have an impact. This represents less than 0.1% of Bitcoin’s total supply. “The remaining ~1.6 million all sit in 32,607 individual, ~50 btc UTXOs, that would take millennia to unlock even in...