Google Study Reveals 6.9M BTC Vulnerable to Quantum Attacks

A recent whitepaper from Google Quantum AI has shed light on the vulnerability of Bitcoin to quantum attacks. Researchers estimate that around one-third of all Bitcoin (BTC) in circulation, approximately 6.9 million coins, are exposed to quantum 'at-rest' attacks due to their permanent public key exposure.

The study, which involved six researchers from Google Quantum AI and external collaborators, found that breaking the 256-bit elliptic curve cryptography used by Bitcoin could require fewer than 500,000 physical qubits. This is a significant reduction from previous estimates, which projected over 317 million physical qubits would be needed to carry out such an attack.

The vulnerability is attributed to Satoshi Nakamoto's decision to use P2PK (Pay-to-Public-Key) addresses in the early days of Bitcoin, where the full public key sits permanently visible on the blockchain. This design choice has left around 1.7 million BTC in P2PK scripts and approximately 6.9 million BTC total across all vulnerable address types exposed.

Google's findings have sparked concerns about the potential impact of quantum computers on Bitcoin's security, with some experts warning that a 'Q-Day' could be looming for the cryptocurrency.