Quote from: o_e_l_e_o on April 11, 2023, 08:31:15 PM

Quote from: temple on April 11, 2023, 07:39:35 PM

-snip-

If we ever reached a point where quantum computers posed a realistic threat to the elliptic curve cryptography that bitcoin uses, then we would fork to a different quantum resistant algorithm to allow bitcoin to continue to move forward. Ideally this would be several years before any real threat from quantum computing, allowing everyone plenty of time to move their coins to these new safe address types. There would be a question to be answered at that point about what would happen to all the so called "lost" coins which weren't moved in time, and whether they were somehow locked to prevent them from being stolen or whether we just let them re-enter circulation.

First of all thank you for the information!

Regarding the first part of your answer, that is a hypothetical situation where many questions come to my mind.

If what I have found so far is correct, the world would have to prepare for that day anyway when SHA-256 could be cracked as it is widely used in many (systemically critical) applications around the world. Essentially (and correct me if I am exaggerating here), the potential susceptibility of SHA-256 to an attack poses a massive systemic risk in many areas of our lives. Now I am not getting off-topic, but trying to get my point across. When we try to establish nuclear surveillance treaties in order to prevent the world from a nuclear disaster, how do we know that not some single country runs a gigantic laboratory researching and trying to build quantum computers that are able to crack vital algorithms in order to then attack or threaten to attack global critical infrastructure?

With more emphasis on Bitcoin, if there was a single actor succeeding in developing quantum computing that could reverse engineer the private key from a public key, what would be the incentive of that actor to go public in all honesty in order to protect the Bitcoin network instead of silently starting to move, for example, Satoshi's coins in the hope that Satoshi doesn't live anymore and can't prove that someone must have obtained a machine to successfully attack the network? What guarantees us that we get aware of the fact in a timely manner that a machine exists such that a fork to a quantum-resistant algorithm can be done (if it's not already too late)?

Would we first have to wait for the machine to exist in order to then fork to a proper new algorithm accordingly? Or could we fork to a different algorithm preventively, in anticipation of a certain computational power most likely being available some time soon? In other words, can a resistant algorithm only be developed once we know what magnitude of computing power we need to be resistant against? I know it is mathematics, but an algorithm is a moving target the same way computing development is a moving target I guess? The reasoning behind this two-fold question is whether we can predict an algorithm that will be sufficient once quantum computing becomes a thing. Or are there infinite degrees of quantum computing and we can only reactively fork instead of proactively?

Quote from: o_e_l_e_o on April 11, 2023, 08:31:15 PM

Quote from: temple on April 11, 2023, 07:39:35 PM

I would also like to ask you where you got the number 2,828.654 BTC from? You have given some answers here to some research that I am into from time to time and perhaps you can elaborate or provide a source.

Certainly.

The theoretical current circulating supply is as follows:

(210,000 * 50) + (210,000 * 25) + (210,000 * 12.5) + ((784,963-629,999) * 6.25) = 19,343,525 BTC

Using the command gettxoutsetinfo on a node will tell you exactly how much bitcoin is within the set of spendable UTXOs. Anything which is unspendable (such as coins which have been sent to OP_RETURN outputs, or coins which miners failed to claim in the first place) will be excluded from this number. This command on my node currently gives the following: 19,343,305.70780786 BTC

Subtract those two numbers and you get 219.29219214 BTC which is not in the UTXO set and therefore is not spendable.

However, there are also some bitcoin which are in the UTXO set but are still provably unspendable. The main example of this is this transaction: https://blockchair.com/bitcoin/address/s-272edf45031dd498e7b3ae89e11ff21b. 2,609.36304319 BTC have been sent to an invalid script which cannot be unlocked, and so these coins cannot be spent.

Add those two numbers together and you arrive at the 2,828 BTC figure I gave above.

For easier tracking, you can use this site (https://bitcoin-supply.com/), which monitors all burned or otherwise provably unspendable bitcoin with a delay of just a few blocks.

This is also useful, thank you. Frankly speaking, I misread the number at first and thought it is 2 million instead of 2k, that is why I was quite surprised that you were aware of such a number. But yes, I am also of the opinion that only these coins you mentioned are actually lost. Many people think (or wish) that only because coins have been dormant for a decade, they should also be excluded from supply, further pumping artificial scarcity of the asset with the help of mental accounting...

Quote from: o_e_l_e_o on April 11, 2023, 02:27:44 PM

Quote from: tbct_mt2 on April 11, 2023, 02:14:46 PM

Lost bitcoins won't be recovered without access to lost private keys. It's impossible as from Private key to Public key then public address is one-way. You can not revert the process from Public address to Public key then Private key.

Not at the moment, but reversing a public key to a private key could certainly be possible far enough in the future with quantum computers. If such an event occurred, then the several million coins in early P2PK outputs as well as any coins in outputs with a revealed public key (which includes all addresses which have previously spent bitcoin) could potentially have their private keys reverse engineered and therefore re-enter circulation, unless the community consensus is to fork to somehow lock all these coins.

Just because coins have not moved in a long time, or even if someone claims they have lost the private keys/seed phrase/wallet/whatever, it is wrong to assume those coins are permanently lost and can't be recovered.

Quote from: tbct_mt2 on April 11, 2023, 02:14:46 PM

However, you won't be able to know how many bitcoins were lost.

We can prove that the number of provably lost bitcoin is 2,828.654 BTC, and this number can be safely removed from both the total and the circulating supplies. Anything which is not provably lost should not be considered removed from the supply.

That part got me thinking because isn't the re-introduction essentially equal to the end of Bitcoin? If a re-introduction occurs, any private key is at risk right in that moment. How would those two events occur simultaneously? 1) reverse-engineer and re-introduce lost coins while 2) fully keep and guarantee security and integrity of the entire network at all times?

And what is your stance on the re-introduction of lost coins? From an economic point of view, it seems to be negligible as the number of proven lost coins is so small. Since we have a highly divisible unit structure, I don't see the economic viability at risk ever for Bitcoin. Do you have some bullet points to share?

I hope you don't get badly struck by my wall of text Wink

and thank you for taking the time!