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Comment by HPsquared | Hacker News Reader

That's what mining is too, basically. It's just that a mining rig can "buy a lot more tickets".

It's not at all what mining is

Miners aren't brute forcing keys to existing wallets and stealing the bitcoin, as that's effectively impossible even for the biggest mining rig (like, a mining rig the size of the sun couldn't do it in a trillion years)

Well that's a different lottery system with much better odds than this.

Technically miners could start mining by trying to guess private keys, but there's no reason to because the expected value is so so much worse.

They really can't though. Asics are designed to do the SHA2(SHA2()) function over and over again. A private key is any number between 1 and 2^256 power. An ASIC arguably couldn't even perform the operations to query the Bitcoin blockchain and see how many unspent UTXO's the private key's corresponding public key controls.

Has someone done the expected cost to find a usable BTC address as well as the expected value of a BTC address? What is the ratio?

Astronomical. You could convert every computer into existence into hunting for used private keys, and run them for the lifetime of the universe, and you’d be unlikely to find even one used key.

What is the expected speed up if using quantum techniques?

Can quantum techniques allow one to more effectively search for a specific private key to a BTC account?

Quantum computers can be used to crack public keys for a bitcoin account yes, but an addresses public keys are only published when a transaction is made

Best practice for secure bitcoin accounts is to always send the entire balance when making a transaction, and have the "change" go back to a new address

Not anymore. With taproot the key used is published on the blockchain when the output is created.

That doesn't make sense.

I haven't published the public key to my bitcoin wallet. If someone sends to my address how do they publish the public key?

There are new output formats with taproot but they aren't mandatory and you can still send to addresses with no published public key

Well, theoretically, instantly. But that’s kind of like asking what if I had this potion that instantly cured every disease known to man and then some, what would happen. What sort of quantum computer are you talking about? How many qubits?

not exactly true

BTC addresses that have never sent BTC are not vulnerable to quantum computers as the public key is only sent when a transaction is made. The address you send to is a hash of the public key and irreversible even with quantum computers

This is no longer the case with Taproot, btw.

The more you know. Thankyou

I think it's square root of classical computing time, using Grover's algorithm.

How do the units work there? The dimensions would be time^(1/2)... That isn't a physical time.

It's it the number of operations which is the square root? (Presumably the different types of computer don't take the same amount of time per operation)

That’s reversing hashes. Finding the private key for a given public key would be basically instant if your quantum computer was large enough.

This isn’t true at all.

Mining involves guessing a salt which, when added to data for a single block’s with of transactions, makes the hash have a certain sum of zeros.

They are only the same in that they are using randomness to search for some number satisfying a given criteria. But, for example, you couldn’t use mining hardware to search for wallets with open balances. The mining hardware is specially optimized for one thing only.

Make me wonder, at what point does brute forcing private keys become more lucrative than mining?

https://odysee.com/@3Blue1Brown:b/how-secure-is-256-bit-secu...

or more briefly: never

You're assuming the crypto is flawless and forever hard, even with new computational paradigms.

We've shown time and time again that our undefeatable algorithms aren't.

Would you be comfortable if the Blockchain was frozen in time for a hundred years, after which you could withdrawal your balance? Would it be impervious over that time frame?

I mean...btc will eventually hit the supply limit. Sort of hilarious if all mining hardware was repurposed at that point to work on brute forcing instead

The supply limit is irrelevant in this case. In order to remain secure, the cost to attack Bitcoin must be proportional to the value represented by Bitcoin. Currently, when proof of work is performed, it is funded in large part by increasing a ledger value without a corresponding decrease elsewhere (aka "minting"). In the future, when proof of work is performed, transaction fees will need to increase in order to provide a similar incentive.

If the sum of the block reward and the transaction fees decreases, then that would result in fewer groups willing to perform proof of work calculations, and would be followed by a decrease in the proof of work difficulty in order to maintain ~1 block every ten minutes. That lowered difficulty then results in a lower cost to attack Bitcoin.

So, there must always, always be profit in running proof of work calculations. Not only that, but to maintain the security of the ledger, any increase in Bitcoin valuation must result in a proportional increase in proof of work expenditure across the entire network. It's an absolute disaster of a system.

What effect would this have on transaction fees, has this been modelled somewhere?

Transaction fees will dominate the block subsidy long before that. Probably within the next 2 decades (in which the subsidy drops 32x).

Yes but, mining is set up to be easier/winnable because adding blocks is necessary.

The opposite is true of finding private keys.

Solo mining yeah definitely, but with pool mining one can at least generate some fraction of a BTC.

I would say "it can solve very big sudokus way too fast"

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