Google Quantum AI published a paper that cuts the estimated hardware needed to crack the elliptic-curve cryptography used by Bitcoin and much of Ethereum by about 20-fold, putting more than $600 billion of crypto value at risk at current prices. The paper says fewer than 500,000 physical qubits could execute the attack circuits in a few minutes, but Google did not say such a machine exists today. The paper estimates about 6.7 million BTC sit in vulnerable addresses, while Ethereum exposure extends beyond wallets to validator, contract, stablecoin, and tokenized-asset control points.