Google Quantum AI has published a paper detailing new estimates for attacking the secp256k1 elliptic curve used by Bitcoin and parts of Ethereum’s ecosystem. According to their calculations, a quantum computer with approximately 1200-1450 logical qubits could recover a Bitcoin private key in about 9-12 minutes after the public key is revealed, which is around the average time for mining a Bitcoin block.

This raises the theoretical possibility of “on-spend” attacks, where transactions could be intercepted and altered before confirmation. While such a quantum computer does not yet exist, the findings highlight that the threat is moving from “science fiction” to an engineering race, urging the crypto community to accelerate the transition to post-quantum cryptography.

The paper also warns about old Bitcoin wallets with publicly known keys holding around 1.7 million BTC, making them prime targets for future quantum attacks. Ethereum faces unique risks related to BLS signatures and KZG commitments.

Source: Google Quantum AI cryptocurrency whitepaper