I think you are talking about Peter Wiulle:
Any unconfirmed transaction in flight exposes public keys, so if a QC exists, at least moving coins around safely becomes impossible. Further, a massive fraction of the currency supply can be taken. Lastly, you likely have exposed your own pubkey already.
Given all those hypothetical attack models that pubkey hashing doesn't help with at all, I think it's fair to say that Bitcoin as it exists today is not quantum secure, period.
It doesn't sound good.
yep, although there's at least
1 solution I can think of:
assuming you trust a miner (and it could be yourself if you have the hashing power, of course), you can give your transaction to a miner out of band, then the public key is never exposed until the tx moving your funds to a QC resistant keypair is already confirmed in a block. That would (hopefully!!!) be a one-off event, but hair-raising (and potentially expensive) all the same
Yeah it was theymos and he got hated bigly with his approach. The way I see is that the stash should be re-introduced slowly as mining rewards, or at least that's how I should have coded it since day 1, since if you are the only guy mining in the world, there isn't even a network and you would get a disproportionate amount of coins as the single participant on the system. At the same time I also think he took the bigger risk, so it should be rewarded... tough call.
I think the only solution is to render the whole P2PK supply unspendable, and to do that with a the longest possible period of advanced warning to give the holders of those private keys sufficient time to move their money. See, we're having a civil conversation about this, yet we already disagree!!! tough call indeed.
hashes could never be "reversed" and it is not exactly about efficiency it is about virtually unlimited solutions. think of it like this, if i say i have a big number that is the sum of 10 other numbers you will never be able to guess what those 10 values were because there simply is too many possibilities.
the difference between hashing and ECC is that ECC is pure math so there could some day be a solution to solve that reverse mathematical problem (ECDLP) in a faster way but hashing is a complete chaotic algorithm where we take an input "mutate" it, toss the bits around and come up with a neat result. so the only way to attack hashing algorithms has always been to find collision meaning if i said "a85845e696ee7aac1b012d611edcbd6fbf1884c5" is my SHA1 hash you will never be able to find out what message i hashed but you could find another message some day (you still can't do it today even for SHA1) that could give the same result.
okay, I am aware of the logic underlying all of this, although you are more familiar with the details.
consider though: mathematicians/computer scientists/cryptographers working for powerful companies/organizations are not compelled to release every breakthrough they discover publicly. What if an efficient solution to what appears to be a brute forcing problem has in fact been discovered? Is that not the point of QC's anyway, to provide efficient solutions for which binary arithmetic Von Neumann machines cannot? Maybe some class of hashing algorithm could be developed to be resistant to such a thing, I simply do not know, but it seems to me that few others can really claim to _know_ either.
People always say "that's impossible", until someone pitches up one day and provides the solution. The fact that we are on this forum having this discussion is the result of exactly that happening: cypherpunks tried to create a Bitcoin, and their imagination for designing it failed several times until satoshi. People literally _couldn't_ believe satoshi initially, Hal Finney hung out with satoshi for a while, contemplating the details of his design, in a way to convince himself that there was not something satoshi was missing. Only once people like Wuille, Maxwell and Todd (as well as Szabo, Dai, and Back on the sidelines) arrived on the scene to contribute to validating the concept did people really begin to get over the disbelief.
*** the following is, to the best of publicly available knowledge, NOT POSSIBLE ***There would be no such luxury under a "SHA reversed by quantum computers" scenario, one minute a single Bitcoin blockchain would exist, the next there would be infinite Bitcoin blockchains, and every Bitcoin client would have their poor little CPUs overloaded trying to figure out which one was the most-worked valid chain
*** the above is to the best of publicly available knowledge, NOT POSSIBLE ***