There are 20 bitcoin wallets worth more than a billion dollars each.
I think it will be pretty obvious when someone gets a quantum computer working.
I think it will be pretty obvious when someone gets a quantum computer working.
Once the cat is out of the bag, everyone will rush to post-quantum cryptography and all that value will be lost in a relatively short period. Indeed, we already witnessed this in the 2010s following the Snowden revelations when big tech, in a concerted effort, adopted HTTPS. Now that is the standard.
For example, "The Fiscal Year 2022 budget appropriation included $65.7 billion for the National Intelligence Program, and $24.1 billion for the Military Intelligence Program."
If Bitcoin would become vulnerable, its value would collapse to zero overnight once it's known. There is limited amount of money anyone could extract before the value collapses.
That is a misleading claim. First: Any quantum key cracker would need to be fast since the operations would all have to be performed within the coherence time, so an attacker could race coins as they were spent or perform small reorgs to steal coins even if they lost the initial race. Secondly: The majority of all circulating coins are stored in addresses which have been reused. Thirdly: the common hashing scheme you mention is 160 bits, so in the presence of quantum computers would only have 80 bits of security against second preimages just by using grover's algorithim and perhaps worse with more specialization (and, in fact, somewhat less considering multi target attacks) which wouldn't and shouldn't be regarded as secure.
> If Bitcoin would become vulnerable, its value would collapse to zero overnight once it's known. There is limited amount of money anyone could extract before the value collapses.
Once its known. There have been insecure altcoins where hackers skimmed them for many months without being noticed. It is indeed technically finite, sure, but large.
Interesting, do you have any statistics on that? But I guess with large exchange wallets, it makes sense.
> only have 80 bits of security against second preimages just by using grover's algorithim
True, but 80 bits are anything but trivial to brute-force using classical computers! I'm not that familiar with quantum complexity, but as I understand it, you'd still need 2^80 quantum operations to brute-force a 160 bit hash.
And for more context: with p2pkh addresses, you are sending to the hash of the address, and hashes are quantum safe.
[0] https://www2.deloitte.com/nl/nl/pages/innovatie/artikelen/qu...