@Nobody_123 - Theoretically: Yes, a powerful quantum computer could "decode" Bitcoin by deriving private keys from public keys (Shor algorithm). However, the impact on mining (SHA-256) is less dramatic (Grover algorithm).
- Practical: Currently and in the near future, quantum computers are not able to crack Bitcoin, as the technology is not yet advanced enough.
- Long term: The Bitcoin community will likely take steps to secure Bitcoin against quantum computers before they pose a real threat.
@Nobody_123 Your assumption is correct. It would theoretically be possible to obtain the keys. However, this becomes more difficult the more up-to-date the address formats are. It is therefore reasonable to assume that the oldest keys/addresses (some of which have been inactive for 10 years) will be cracked first, but everyone else could update or switch to better ones by then.
@Cro Cold wallet is useless in this case. The only thing that would help is switching to a post-quantum secure procedure. But I imagine the migration from the current status to that would be very funny.
