Part 4/10:
- Long-range attacks: Far more concerning, these target addresses where the public key has already been exposed on the blockchain—namely, addresses from which coins have been sent or reused. An attacker with unlimited time and a powerful quantum computer could theoretically break the cryptography protecting these addresses, especially those created with Taproot. This risk affects approximately 6.51 million Bitcoin—nearly a third of the total supply—worth over $700 billion.