A new report from ARK Invest warns that roughly 6.9 million Bitcoin—worth about $483 billion at a $70,000 median price—could eventually be exposed to quantum computing attacks.
The risk centers on elliptic curve cryptography (ECC), the system that secures Bitcoin ownership through digital signatures.
Bitcoin uses the Elliptic Curve Digital Signature Algorithm (ECDSA) over the secp256k1 curve.
According to ARK’s analysis, quantum computers running algorithms like Shor’s algorithm could theoretically derive private keys from public keys, allowing attackers to steal funds.
However, the threat is unevenly distributed across the network.
Bitcoin’s Oldest Wallets Are Most Vulnerable
The report estimates that about 1.7 million BTC sits in early address formats such as P2PK, where the public key is already visible on-chain.
Many of these coins are assumed lost, meaning they cannot be moved to safer address types.
Another ~5.2 million BTC remains technically vulnerable but could be migrated to newer address formats if holders move their funds before quantum capabilities reach critical levels.
Together, that represents roughly one-third of Bitcoin’s total supply potentially exposed under a worst-case quantum scenario.
Still, experts stress that current quantum technology does not pose an immediate threat.
Today’s machines operate in what researchers call the Noisy Intermediate-Scale Quantum (NISQ) era.
Experimental systems have achieved fewer than a hundred logical qubits with high error rates.
By contrast, breaking Bitcoin’s 256-bit elliptic curve would likely require thousands of stable logical qubits and billions of quantum operations.
As a result, the report frames the risk as a gradual technological progression, not a sudden “Q-Day” event.
The Race Between Quantum Breakthroughs and Bitcoin Upgrades
Nevertheless, the Bitcoin ecosystem has started preparing.
A recently proposed upgrade, BIP-360, aims to introduce quantum-resistant address structures compatible with Taproot, allowing the network to transition toward post-quantum cryptography if needed.
For now, the primary challenge is not imminent quantum attacks but monitoring technological progress and migrating vulnerable coins before such capabilities emerge.
In other words, Bitcoin’s quantum threat may ultimately become less about computing breakthroughs—and more about whether the network upgrades in time.
