Blockchain analysis shows that 1.5–2 million BTC, mostly from early addresses (2009–2011), have exposed public keys due to transactions. These are vulnerable to future quantum computers with 3000 logical qubits, which could use Shor’s algorithm to derive private keys in hours to days. Such quantum advancements are expected between 2030 and 2050, per IBM and Google roadmaps.
Modern HD wallets protect new addresses by generating a new one per transaction, keeping public keys hidden until used. This makes new addresses resistant to quantum attacks. Even current quantum computers like Google’s Willow (105 physical qubits) pose no threat, as they’re far from the required 2000–3000 logical qubits.
A quantum-resistant Bitcoin, using post-quantum algorithms (e.g., lattice-based cryptography), will only protect newly created addresses. Old addresses with exposed public keys will remain vulnerable unless funds are manually transferred to new, secure addresses before an attack. These old addresses are likely to be compromised when the technology arrives.
Compromising these addresses could cause a market shock, as releasing 1.5–2 million BTC may trigger a sharp price drop, potentially 20–50% or more, due to panic and market flooding. However, this would return coins considered permanently lost to circulation, increasing liquidity.
Long-term, this is unlikely to harm Bitcoin. Instead, adopting quantum-resistant cryptography will make the network more secure, and unlocking unused coins will increase the usable percentage of the total supply. This could boost confidence and support Bitcoin’s growth as a more robust and secure system.