Quote from: jackg on September 23, 2017, 11:30:23 PM

Im not sure I understand this the way you do. I don't think you can generate private keys from a public key with the way you suggest. It's possible to get the private key by brute forcing to reveal every private key (which, in quantum computing would be considered a great accomplishment). It's unreasonable to imagine now, but one day it could be possible.

If I'm wrong here, can you help by posting a theoretical algorithm about how the private keys can be brute forced from a public key. Also, by public keys, that could be xpub, mpk or a bitcoin address as they are all technically public keys, although presumably this relates to xpub.

Well, I am pretty sure that what he meant was that you need a public key in order to figure out the private key using a quantum computer. The hashing of the public key would not be possible to be done as quickly on quantum computer due to the way the work. I have no clue how exactly these quantum computers should work, but to be honest, no one really does in detail either, they are just tests currently and don't really offer anything useful now. No one really understands the quantum physics, they make no logical sense, they are paradoxes that we can't solve, but are trying to utilize.

There is something called Shor's algorithm https://en.wikipedia.org/wiki/Shor's_algorithm
That, to my understanding, is using a public key to find a private key, however on Wikipedia they talk about RSA keys and Bitcoin uses ECDSA, but I know that ECDSA require even smaller quantum computers, due to the efficiency of the algorithm. Shor's algorithm doesn't generate new public/private key pairs, but finds the period for a certain public key, from which it derives the private key. It requires a bit of understanding of RSA keys to know what it does, but that is the idea.

Quote from: suppersz on September 24, 2017, 03:02:15 AM

Is having a multisig address more secure? Is that sort of what this guy is asking about right now?

Other than the fact that you need multiple keys to break, not really. No, he is talking about randomness of generating keys.

Quote from: smokeydog on September 24, 2017, 05:32:03 PM

Don't waste your time wondering about cryptography.

-snip-

Trying to take on key pair encryption, digital signatures and all the internals of bitcoin's block chain will take more time then you have left on this earth when you add in all the other stuff you need to do.

I will say that in my opinion, not even the NSA will be able to crack you private key let along the billions of others being generated. For now it's safe.

It really isn't that complex. You could really learn it all in one course at collage. The tech used here is quite new and there isn't that much of it.
It would take a lot of time to learn the history, but the present technology has little to do with it. So my advice would be the opposite of yours, don't learn history, learn the present.

Quote from: xIIImaL on September 25, 2017, 06:02:00 PM

Quote from: suppersz on September 25, 2017, 12:23:15 PM

well those private keys derived from brain wallets were pretty bad actually. They are not really private keys, but still, I guess you can think of it that way, and brain wallets are absolutely terrible security

Private keys generated in the online wallet might be shared to you and hold by the wallet providers. But hardware wallets and desktop wallet are unique can be utilize by the user alone. Henceforth private key is much safer for you to import the wallet and hold the amount in the wallet with much safety. To whom may ever, don't share your private key and wallet.dat file to keep your wallet safe.

Some of the brain wallets were less secure then a normal desktop wallet and even less then a hardware wallet. They were easily guessable.
The online wallet is hardly a wallet, we should all know that, but we are not even discussing this right now. Calling an online wallet a wallet is like calling your online bank account a wallet.