Quote from: exstasie on December 10, 2018, 08:40:15 PM

There's a world of difference between those two situations. The existence of sophisticated QC doesn't make cracking keys instant. It's pretty much accepted at this point that Bitcoin's signature algorithm could be broken in a few years, perhaps ten years in a best case scenario. But it'll take much longer than that to develop QC that can do so in the time it takes a transaction to confirm.

Also, Bitcoin users don't expose public keys unless they're spending. Until they spend from an address, the only thing exposed is a hash of the public key. So we're mainly worried about people who reuse addresses and people who have exposed public keys (to third party services or via Pay-to-IP which was removed from the reference client several years back).

https://medium.com/@sashagnip/how-many-bitcoins-are-vulnerable-to-a-hypothetical-quantum-attack-3e59e4172e8
Quote:
"as of 2018 June 4: 19% addresses (4,242,958 of 22,275,753) that hold 36% bitcoins (6,080,090 of 17,072,361) reveal their public keys."

Other bitcoin holders should be worried too in case if 6,000,000 bitcoins will be sold on exchanges.

Quote from: Silberman on December 12, 2018, 10:28:33 PM

The development of quantum computers is very slow so we have more time than that to implement algorithms that are resistant to quantum computers, so you are worrying for something that is not going to happen, it is very easy to think that something can destroy bitcoin but 10 years have passed and governments have been unable to find anything that comes close to that.

Don't worry, quantum-resistant algorithms are already developed. Bitcoin Post-Quantum fork serves the purpose of conducting an experiment about using them in Bitcoin. When it becomes necessary, these algorithms can be embedded in Bitcoin.