G7 Warns: Migrate to Post-Quantum Crypto or Risk Quantum-Proof Hack

The G7 Cybersecurity Working Group has published a joint statement urging public authorities and companies to migrate to post-quantum cryptography immediately. This is in response to the growing threat of quantum computers, which could potentially break current encryption methods.

For Bitcoin holders, this means that their addresses may be vulnerable to an attack if they have revealed their public key at any point. According to estimates, around 6.8 million BTC are exposed, with a significant portion being from early mining payouts and Satoshi Nakamoto's holdings.

The statement warns of 'harvest now, decrypt later' attacks, where data is captured and stored in encrypted form today to be decrypted later with a quantum computer. However, for public blockchains like Bitcoin, the problem is more straightforward: an attacker doesn't need to collect data as it's already visible on the chain.

Bitcoin uses key pairs to secure balances, with the private key used to sign spends and the public key derived from it being visible on the network. A quantum computer would use Shor's algorithm to reverse-engineer the private key, but only if the address has revealed its public key at some point.

The first European milestone for the switch to quantum-safe methods expires at the end of 2026. Bitcoin holders can check their own position in just a few minutes by using a block explorer and checking the format of their receiving addresses.