Topic: Transaction Finality on Bitcoin - page 2. (Read 770 times)

The problem there is, I don't think you'll be able to convince me that they are wrong while you have such fundamental misconceptions over the supposed importance of checkpoints.  Your "detailed examples" are based on a flawed premise.  If you ever reach a better understanding of the matter, perhaps I'll reconsider.

The fact that nobody has done this doesn't mean that it can't be done. Right now there are couldwith such a weak PoW network that it would cost a few bucks to attack them with a 51% attack. See:https://www.crypto51.app/

Is anybody attacking them? Maybe. You and I don't care to even look into it most probably, but that doesn't mean it's not happening.
Is it feasible to attack them? Most certainly yes and it has been done in the past. Goldcoin is a good example.

Theoretical attacks deserve as much attention, the fact that they remain in theory doesn't mean they aren't feasibe and that they don't pose as weaknesses of consensus algorithms.

It's worth pointing out that we're giving someone ample opportunity to plug their coin, when such blatant advertising should be happening in the altcoin board.  If we're not going to steer the conversation back towards Bitcoin, I'd call for this topic to be locked/moved.

The question as to why Bitcoin no longer uses checkpoints is answered rather well here.  I hope this clears up any confusion some people might be having.

OK, then we are back to the debate that stakers are incentivized to sign each, and every fork, because it costs them nothing. Plus if the only "challenge" to start doing it is modifying the software to enable signing each, and every fork, then good luck to finality in POS.

Or their network is centralized to several stakers/validators who understand each other, that it's also not worth attacking. Buying up their cryptocurrency would be giving them a favor. Hahaha.

to attack a network and put it to test there has to be incentives, when that network is garbage and the reward is so small that it doesn't even cover the cost of time spent looking into the garbage then it will never be attacked and it could create the illusion of being safe just because it hasn't been attacked.

Is that all? That's the prevention of stakers from signing in each and every fork, at no costs? Good luck with POS finality.


Zeit removed the fees? What are the incentives to stake, and to secure the network? That's not a network for a hostile environment.

I still have a lot to learn about how "transaction finality" works on both consensus algorithms (PoW and PoS). For once, I've thought that the energy spent on PoW chains like Bitcoin and Ethereum, meant that transactions were considered as final (unlike PoS chains of today). Thankfully, you've helped me understand this better after some confusion related to the subject. I can now see why Ethereum is after "transaction finality" with its Casper PoS upgrade. Smart contracts need a truly immutable blockchain where transactions are considered as final no matter what. Those who try to cheat the system will get penalized. It's a clever idea from the ETH dev team, which could serve as a great example for Bitcoin and other altcoins.

While I don't like coded checkpoints because of their centralization, the latter option (rolling checkpoints) seem to be a better solution for maintaining transaction finality on the Bitcoin blockchain. I'm surprised that BTC devs are not interested in doing something like this, in order to make Bitcoin as immutable as possible. The current hashrate distribution on mining pools owned by Bitmain/China could put the blockchain at risk in the long term. After all, they already control 51% of the network's hashrate. There are solutions to tackle this problem, though. Betterhash, and Stratum V2 aim to make mining more decentralized. With a decentralized PoW consensus and rolling checkpoints, you could rest assured that Bitcoin's transaction history will remain unalterable for the foreseeable future.

But I guess that, developers are mostly interested in scaling the BTC blockchain than anything else. Of course, that's also important for the mainstream adoption of Bitcoin. But I believe that, security and reliability goes above anything else. As long as there's no threat of a 51% attack or block reorg, developers wouldn't care more or less implementing a mechanism that would make transactions final no matter what.



Yes. That's the way it works, according to the Bitcoin whitepaper. The longest running chain is the one that's considered as valid among all participants. We could say that Bitcoin experiences small forks every once in a while because of this. The situation is worse with PoW chains that have huge block sizes (like BCH and BSV). I've seen that Bitcoin SV has experienced a lot of block reorgs lately. In a chain like this, it's hard to think that transactions will ever be considered as "final". Maybe that's why BTC devs decided not to increase the block size in order to maintain Bitcoin as secure as possible. A 1mb block size has worked flawlessly for the Bitcoin blockchain where block reorgs have been quire rare (AFAIK). But I strongly believe that Bitcoin devs should look for ways to implement transaction finality on-chain to maintain the immutability of Bitcoin for the foreseeable future.

Attack the debate, read my post and explain how the theory can't be put into practice? A need for a "multi-stake client"? Is that term your own invention? I believe so.

On the topic of finality, POS requires/or WILL require checkpoints.

How this confirmation becomes arbitrary? I often got experience this when Im doing some transactions on different exchange. The confirmation varies and they have different figures such as Binance, Kucoin, and even wallet transactions. Is the exchange changing it or the blockchain securing this confirmation and validation or they just prefer it depends on the level of security that is being process?

Newbies, Nothing at Stake is NOT a myth. It's a known theoretical weakness in POS. In POS, a bad actor will not lose anything if he/she misbehaves, by signing in each and every fork. In fact, it encourages them to sign each and every fork because there are no costs.

Ethereum is concerned with "transaction finality" because they want to switch to PoS, and in PoS 51% attacks are more dangerous because of the "nothing at stake" problem, which is why they try to invent some countermeasures to deal with this problem. Bitcoin is a PoW currency, so you don't have to worry about it as long as the hashrate remains big enough, and currently it's really big and keeps growing.

It's somewhat alright to accept zero-conf transactions if it ticks a few criteria. Generally, with opt-in RBF flag in the transaction, it is a very high risk transaction since the ease of double spending that transaction is extremely high; anyone can easily replace it with another transaction to an alternative address. In a brick-and-mortar store where the customer would want a fast transaction settlement, it would be more advisable to accept zero-conf transaction following a risk assessment.

Once it has one confirmation at least, it is generally safe to accept transaction of a decent value.

I apologize for the concern, but I am concerned about one question, how vulnerable the transaction can be, until the first confirmation, since I used to consider the blockchain bitcoin flawless at all levels of its use.  Is it possible to cancel a transaction before the first confirmation in the bitcoin blockchain?  I understand that many blockchains and different coins have flaws and especially the facts of vulnerability, but there is nowhere to get information about the real possibilities of loss.

I once too became curious about how many confirmation is needed in order to completely verify a transaction, and why does it needs to have more than 2 confirmation just to completely made a transaction successful. With this regard, I have came up to conclusion that the transaction is quite more secured based from the number of confirmation it gets from the miners.

Most of the time, the transactions I've created is already been processed with just at least 3 confirmation on the network.

The smaller coins have encountered 51% attack before and it was profitable for them due to the relatively lower cost of the attack as compared to the amount double spent. It is important to consider the number of confirmations required to the total value of the transaction. For the lower value transaction, it's possible for the transaction to be instantaneous if the merchant is willing to take the risk for the sake of a faster and smoother checkout. For exchange, they usually require a much higher number of confirmations. Up till 5 confirmations, the risk of double spending with less than 51% of the network is still possible (albeit still rather expensive and requires some luck).

it is not that complicated to know. it is a matter of cryptography. in order to reverse a transaction that is already confirmed you have to mine the same block. but the problem is that you have to first have a huge hashrate that allows you to mine that block within reasonable time. lets say it is block #100, while you are mining that again the rest of the world is mining #101 and by the time you find #100 the rest of the world is on #102 now you are 2 blocks behind and the chain you have is a shorter one with less work that is rejected.

It depends on the system of the exchange to give exact figures. in fact it is just a number to confirm exactly which blocks of blocks have been received to process or not. exchanges usually only need 3-5 confirmations of completing a transaction and this is quite normal. When an error occurs, the blocks will surely stop processing and be canceled, then the system will notify that your transaction has failed and ask you to make a new transaction. Simply put, the blockchain system is quite smart and you don't need to worry too much about this.

Exactly. The more confirmations a transaction has, the lesser the probability of "rollbacks" will be. Since Bitcoin is the most secure Blockchain network today, a single confirmation might be all you need to feel safe without worrying about getting your funds "double-spent". The real deal will be with smaller blockchain networks which are easily prone to a 51% attack. Maybe the Ethereum developer team have been concerned about transaction finality because of security issues within the chain? After all, Ethereum is not as secure as Bitcoin is in terms of hashrate.

One thing for sure, is that transactions made on PoW blockchains are considered as "final" while that's not the case with PoS blockchains (someone correct me if I'm wrong). The amount of energy spent mining Bitcoin compensates for the security and reliability of the entire Blockchain network. It could be said that transactions on the Bitcoin blockchain are considered as final after a couple of network confirmations. But no one knows for sure, as Blockchain technology is still being thoroughly tested within the mainstream world. Just my thoughts

Bitcoin's blockchain records basically the money flow. It doesn't care about the actual wallet and how "final" you feel the funds in it are.

This being said, all you know is if an input has "enough" (which can have various meanings) number of confirmations and you can or cannot spend it (it's yours or not). That's just simply all.