Pages:
Author

Topic: Is 51% attack a double-spending threat to bitcoin? (Read 912 times)

legendary
Activity: 2870
Merit: 7490
Crypto Swap Exchange
aliashraf, I thought of asking you in the other "51%" topic, but I believe it's better suited here.

Considering all your thoughts about what, and debates against the full nodes, would it be in your opinion that Bitcoin Cash is "potentially" a better network than Bitcoin?

IMO you better make new thread with title such as "Miner, 51% attack and full nodes", since you'll derail this thread.
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
aliashraf, I thought of asking you in the other "51%" topic, but I believe it's better suited here.

Considering all your thoughts about what, and debates against the full nodes, would it be in your opinion that Bitcoin Cash is "potentially" a better network than Bitcoin?
To be short and comprehensive: No, I hate bcash, because they did what nobody should do ever with a great project such as bitcoin: worsening the problems. By increasing the block size they ruined any chance for solo miners to exist because of proximity premium consequences.

As of full nodes, I don't think the arguments made by the other side about Raspberry Pi nodes hold enough water. It was not is not about poor users who couldn't afford an average pc or VPS for running a full node, it is about the centralization of mining.

P.S.
I think revisiting the block size debate or your general concerns about full nodes is a good idea but as @ETFbitcoin has suggested it'd be better if you start a new thread for this.
legendary
Activity: 2898
Merit: 1823
aliashraf, I thought of asking you in the other "51%" topic, but I believe it's better suited here.

Considering all your thoughts about what, and debates against the full nodes, would it be in your opinion that Bitcoin Cash is "potentially" a better network than Bitcoin?
legendary
Activity: 2898
Merit: 1823

4- I've also another project under the hood, one would consider it as a decentralized mining pool based on a whole new technology other than what is perceived from this concept now. For such projects to be of any value for helping bitcoin mining to become compatible with the original design, we need to be more sensitive and serious about the mining scene of bitcoin and recognize such efforts as being legitimate and important instead of alienating them and insisting on mining as a fringe world.


No one is alienating the miners. They are an important part of the community, BUT, don't expect the community to submit to their demands. They tried to politicize the use of BIP-9 once, and they had the UASF to crack them.

Good luck to your project, that you have been teasing us for a long time.
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
Thank you very much guys for joining this conversation. Few points to answer some FAQ and I'll be discontinuing this thread. Feel free to add your comments if any but I won't follow anymore:

1- I started this thread for one simple purpose: Re-visiting some of the ideological standpoints of bitcoin community as of these days which has distracted us from PoW and its crucial role in bitcoin both conceptually and historically.

2- I did it because I see many occasions in PoW for improving the state of bitcoin which are ignored or denied after the shameful bch fork.

3- As of specific improvement proposals, I discussed UTXO commitment and reminded of Drivechain scaling proposals which are under attack because they seem to rely too much on PoW they are both examples of how a minor, tolerable soft-fork could help bitcoin to get in better shape and instead it is blocked because of vague anti-PoW assumptions, I tried to debunk here.

4- I've also another project under the hood, one would consider it as a decentralized mining pool based on a whole new technology other than what is perceived from this concept now. For such projects to be of any value for helping bitcoin mining to become compatible with the original design, we need to be more sensitive and serious about the mining scene of bitcoin and recognize such efforts as being legitimate and important instead of alienating them and insisting on mining as a fringe world.

Finally, I have to clarify that I'm not an anti-core warrior (or a big-block enthusiast or PoS trojan or something) who has nothing to do other than attacking Greg Maxwell or Adam Back or other nice people we all feel deep respect for, the thing is, sometimes they go politics too much and do not let themselves and people to think out of the box. I understand bitcoin is under attack from many sides and people run sophisticated schemes to fail bitcoin and to take advantage of such a failure and these guys have every right to be sensitive and sharp but we have to think and re-think and discuss as well and it is absolutely necessary to avoid sectarianism at the same time.
legendary
Activity: 3724
Merit: 3063
Leave no FUD unchallenged
1- There is just one hypothetical threat that full nodes can ever detect: illegal inflation of bitcoins. There is no other threat to bitcoin that full-nodes are capable to detect not mentioning their inability to mitigate.

Wrong.  There are numerous consensus rules that full nodes perform checks to ensure each blocks conforms to.  Please refer to this wiki article for a list.  If ANY of those rules are breached, the node will reject the block.
Really? Bitcoin wiki? Interesting!

FYI: Besides ordinary transaction processing, bitcoin consensus rules serve just two canonical purposes:1) mitigating the double-spending problem and 2) regulating the rate of bitcoin issuance. You can look at the two as one big target: preserving the scarcity of bitcoin as planned by the protocol, i.e. inflation control. 

How about, before you go spouting "FYI" at people, you could perhaps ensure that the "information" you are providing is accurate?

You are still talking nonsense.  What really would be interesting is if you actually read the wiki and made at least some attempt to understand Bitcoin before you delve down the path of espousing a solution which is still looking for a problem to solve.
legendary
Activity: 1876
Merit: 1157
No, I am actually trying to understand the argument you are making and seems to me that you take a lot of things on good faith for the game theory to work. In the replies above, you have repeatedly said that miners will be kept in check because "community", "media" will know as soon as anything happens. But this has to be detected right? That is what a full node does and in a decentralized system, we need more of them.
For getting rid of a false discourse, one should absolutely remain focused.
--snip--
I appreciate your effort in trying to convince me but I have thought for myself. For reasons i mentioned before, I do not think that this is a false discourse. In the current form of its implementation, Full Nodes are indispensable to the bitcoin network. Those that think otherwise are trying their own methods.

Core devs of bitcoin somehow have become convinced that bitcoin is what it is and there is no hope to do anything disruptive about the two BIG problems: Centralization of Mining and Scaling. They've gone that far to adopt Buterin's stupid Trilemma assertion about denouncing feasibility of solving the two at the same time (with a fake third factor, security, he has added to emulate something he has read in high school, the Combined Gas Law Cheesy).
You are reading too much into the thoughts and minds of core devs. I think their sole motivation is infallibility and robustness of bitcoin which leads to a conservative approach, understandably so. The discussions that happen at the bitcoin mailing list and the activity in bitcoin repository are proof that it is open-to-all and everyone is trying to find a better way forward.

I'm advocating for both: decentralization of mining and scaling bitcoin at the same time but it is very important to note: a decentralized mining scene needs full nodes, many many of them, solo miners are full nodes, remember?
So, I'm the one who truly loves full nodes. The give-up strategist? No, he is just a fake lover.
This idea assumes two things:
1.) Implementation, testing and adoption of fundamental changes to the block structures such that pools are no longer needed. Do you know of any such implementation? Working code, testnet, altcoin ?
2.) It also assumes that One node= One vote. This is no longer the case due to ASICs. The fundamental assumption that everyone running the core client would also own hashpower changed with ASICs. That is why, in the current reality, Full nodes are what they are, till of course we have alternative implementations.

I'll bow out of this discussion for now with one last word. Code speaks louder than words/ advocacy. 
newbie
Activity: 16
Merit: 4
I see no confusion in what you have quoted from me. It is crystal clear: Your claim about full nodes playing such a crucial role in bitcoin is simply wrong and baseless. As I've extensively discussed up-thread, full nodes have nothing to do with the network security, they are just useful for the entities who own them as a single body to keep them somewhat more secure against some attacks that are not considered realistic anyway.

Either you are incorrect, or unclear, or both.

I read the article you've linked, the day it was published, good statistics about Ethereum but nothing new for bitcoin,

That's great, good for you.

Ethereum's snapshots. The latter is vulnerable to short-range attacks UTXO commitment is not!

Feel free to describe it.

the same blind enthusiasm about current bitcoin. Put some real meat on the table, please. Cheesy .. which is really a stupid paranoia. It could also be considered a forgery of concepts to spread FUD about the mining scene of bitcoin for political reasons, again, stupid.

It's a challenge to take you for serious when you write like this. It's unclear what you are trying to say, if anything.

A 51% attack would not let through a double-spend
Last to respond to your question in the thread's title, "Is 51% attack a double-spending threat to Bitcoin?", I guess you have the answer already: It is not.
Why? According to you, it is because full nodes won't allow it but my argument is more solid: It is not gonna happen because it will be revealed anyways and destroy the attacker completely beforehand. Bitcoin inflation rules are currently parts of a social contract, rather than some lines of code, it is hard to understand but you should try.

Why did you make a thread with the title "Re: Is 51% attack a double-spending threat to bitcoin?" - a question to which the answer is no - to discuss a Bitcoin fork?

You suggest a "it (doublespends?) will be revealed anyways (now how, unlike how else?) and destroy the attacker completely beforehand (how?)" related to "Bitcoin inflation rules" in the "social contract, rather than some lines of code".

Are you trying to communicate a Bitcoin fork or protocol feature suggestion?

Anyhow this was my last post here.
legendary
Activity: 2898
Merit: 1823
Relaying blocks is not a big deal. Your argument is not qualified enough to be discussed here, sorry, blocks get relayed anyway, e.g by collided pools.


I don't see how this part of your post is right. That is simply wrong, and I doubt you truly understand how the Bitcoin network works.


Blocks are relayed to any client, being a mining full node, a full node wallet, an SPV wallet, a blockchain explorer, ...) who connect to a pool/solo-miner and/or any full node that accepts inbound connections. What do you mean by accusing me of being ignorant about bitcoin relay network? It is not so complicated and I've been discussing it on many occasions in this forum.


Because they are ONLY connected to a full node, that validates, the clients that ONLY connect to the full node DON'T DO anything for the network, and are NOT truly part of the network.


How? Let's dive in:

There is a very efficient, secure way of running a bitcoin full node on commodity mobile devices very efficiently in economic mode, called UTXO commitment. According to this model miners would have to commit to the UTXO (state of the bitcoin machine) by somehow including its hash in their blocks and a light full-node could besides synchronizing headers like a usual SPV wallet continue to downloading the full state of the machine as of latest couples of hundreds of blocks and act like an ordinary pruned full node thereafter. Right?


If "that" doesn't validate and relay transactions/blocks, then it's not doing anything for the network, and therefore not part of the network.


"That" is an ordinary bitcoin pruned full node and does everything an ordinary full node can do other than uploading the ancient history of blockchain for the current (stupid) bootstrap process.


Listen, if it's not validating, and relaying blocks. It's not part of the network.
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
1- There is just one hypothetical threat that full nodes can ever detect: illegal inflation of bitcoins. There is no other threat to bitcoin that full-nodes are capable to detect not mentioning their inability to mitigate.

Wrong.  There are numerous consensus rules that full nodes perform checks to ensure each blocks conforms to.  Please refer to this wiki article for a list.  If ANY of those rules are breached, the node will reject the block.
Really? Bitcoin wiki? Interesting!

FYI: Besides ordinary transaction processing, bitcoin consensus rules serve just two canonical purposes:1) mitigating the double-spending problem and 2) regulating the rate of bitcoin issuance. You can look at the two as one big target: preserving the scarcity of bitcoin as planned by the protocol, i.e. inflation control. 
legendary
Activity: 3724
Merit: 3063
Leave no FUD unchallenged
1- There is just one hypothetical threat that full nodes can ever detect: illegal inflation of bitcoins. There is no other threat to bitcoin that full-nodes are capable to detect not mentioning their inability to mitigate.

Wrong.  There are numerous consensus rules that full nodes perform checks to ensure each blocks conforms to.  Please refer to this wiki article for a list.  If ANY of those rules are breached, the node will reject the block.
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
No, I am actually trying to understand the argument you are making and seems to me that you take a lot of things on good faith for the game theory to work. In the replies above, you have repeatedly said that miners will be kept in check because "community", "media" will know as soon as anything happens. But this has to be detected right? That is what a full node does and in a decentralized system, we need more of them.
For getting rid of a false discourse, one should absolutely remain focused.

1- There is just one hypothetical threat that full nodes can ever detect: illegal inflation of bitcoins. There is no other threat to bitcoin that full-nodes are capable to detect not mentioning their inability to mitigate.

2- Illegal inflation of bitcoin is possible either by allowing multiple copies of a coin to circulate around (double-spending) or by printing bitcoin out of thin air.

3- Both threats are considered existential. A single instance of such a catastrophic event will destroy bitcoin and the whole cryptocurrency ecosystem practically. We are talking about 2 hundred billion dollars being at stake at the time of this writing.

4- In bitcoin, PoW is designed as the solution for this threat with game theory as the backup solution for the centralization possibilities and 51% problem.

5- With the centralization of mining we experienced soon after less than a couple of years from the Genesis, we are existing in the edges of a 51% attack for almost a decade now. Fortunately, game theory is doing well and we are good, for now, and probably for a long time.

6- Centralization of mining because of pools is bad and should be addressed somehow.

7- In the meantime, we have a scaling problem and some other less critical ones like privacy issues, they are to be addressed, as well.

Now here is the problem:
Core devs of bitcoin somehow have become convinced that bitcoin is what it is and there is no hope to do anything disruptive about the two BIG problems: Centralization of Mining and Scaling. They've gone that far to adopt Buterin's stupid Trilemma assertion about denouncing feasibility of solving the two at the same time (with a fake third factor, security, he has added to emulate something he has read in high school, the Combined Gas Law Cheesy).

This give-up strategy was first triggered by the embracing raw scaling proposals like th one gave birth to bcash after the scaling debate. People went all-in on the idea of every scaling idea is somehow related to a suspicious centralization agenda, just like bcash.

Well, it was obviously just a stupid and naive generalization, but it got viral and became a part of the culture and now it is time to get rid of it, ok?

One important part of this give-up strategy is the exaggerated and artificial distinction between full nodes and miners. Originally, bitcoin does not make such a distinction between the two, right now bitcoin client code has a built-in mining feature and every full-node is officially (not practically) a mining node too!

The give-up strategy is primarily a give-up on PoW. By advertising full-nodes as the superheroes of security and decentralization, other than getting off-track from bitcoin's most important innovation, Proof of Work, the most revolutionary phenomenon in the 21st century for the least, this strategy is neutralizing any opportunity to improve the situation.

I'm advocating for both: decentralization of mining and scaling bitcoin at the same time but it is very important to note: a decentralized mining scene needs full nodes, many many of them, solo miners are full nodes, remember?
So, I'm the one who truly loves full nodes. The give-up strategist? No, he is just a fake lover.

Alienating scaling/mass-adoption/decentralization proposals by spreading FUD about PoW is an alien discourse and has nothing to do with bitcoin white paper.
This is a loaded political statement regarding the bitcoin developers and i personally don't agree with it, whatever my opinion counts for. IMO, there is no "True Vision" in bitcoin whitepaper that needs a zealous following. Satoshi wouldn't have shared his humongous work on a public forum to cypherpunks all over the world in an easy to modify repository if he thought that "his whitepaper" is the end-all for everything.
One point: I'm not the one who started it, and I'm not the one who continues it. People, dev or not,  should take care of their attitude and behave sanely. The one who starts a war is not always the one who ends it. Politicizing bitcoin development proposals is not my option, it is how you are treated when you are discussing critical issues in bitcoin.
legendary
Activity: 1876
Merit: 1157
I think this is again pretty much a question of what you think bitcoin is. A lot of people out there think a lot of things about what bitcoin is and there are claims from con-marketeers about "Real Bitcoin" "True Vision" etc etc.  If you feel that we CAN trust miners, media can be believed to disseminate trustworthy information, full nodes are not needed etc etc. then there are plenty of other centralized scaling approaches out there.

If we take all these issues on privacy, trust on miners, media etc for granted then you are not in agreement with the privacy and security model of bitcoin made possible because of full nodes.
I think you are now somehow agitated by the previous embracing post of the fake Asterisk id, aren't you? it is what they do, they trigger anxiety and push buttons, be careful.
No, I am actually trying to understand the argument you are making and seems to me that you take a lot of things on good faith for the game theory to work. In the replies above, you have repeatedly said that miners will be kept in check because "community", "media" will know as soon as anything happens. But this has to be detected right? That is what a full node does and in a decentralized system we need more of them.

You then say that SPV nodes are sufficient for this which they clearly are not. SPV nodes themselves rely on full nodes for consensus verification. The only case that possibly stands is that of the network relying on pruned nodes rather than archival full nodes. I am still reading on this pruned nodes vs archival full node comparison in how one is better than the other for the network.

When we are talking about benefits of propagation among non-mining nodes in case mining nodes become unreliable, you said that full nodes are not necessary for propagation too as SPV nodes can provide the network service. But, the important thing is they DO NOT validate. We can agree that SPV nodes aren't much use to the network per se, except for being an easy way to provide wallet services to individual users without downloading the full blockchain.

I am also convinced that in its present state, the network of full nodes is still the best D-day option we have. You took a tangent to your old proposals in denying that but well, an idea is just an idea. It cannot be used to refute the actual requirements for bitcoin network.  

Alienating scaling/mass-adoption/decentralization proposals by spreading FUD about PoW is an alien discourse and has nothing to do with bitcoin white paper.
This is a loaded political statement regarding the bitcoin developers and i personally don't agree with it, whatever my opinion counts for. IMO, there is no "True Vision" in bitcoin whitepaper that needs a zealous following. Satoshi wouldn't have shared his humongous work on a public forum to cypherpunks all over the world in an easy to modify repository if he thought that "his whitepaper" is the end-all for everything.


PS: I think it'd be good if we can continue this somewhere other than "Technical Discussion". I just don't feel qualified enough for this sub in discussing these basics.. Tongue
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
Are we clear? This full-node, full-node propaganda is totally fake and misleading. It is not a campaign in favor of empowering bitcoin users by giving them an opportunity to run a full node, it is just a trick to relying less and less on miners in a baseless and paranoid way: Who in the hell can imagine a scenario in which miners are colliding for 3-4 days to inject a few false UTXOS in bitcoin blockchain? A paranoid or a politician.
I think this is again pretty much a question of what you think bitcoin is. A lot of people out there think a lot of things about what bitcoin is and there are claims from con-marketeers about "Real Bitcoin" "True Vision" etc etc.  If you feel that we CAN trust miners, media can be believed to disseminate trustworthy information, full nodes are not needed etc etc. then there are plenty of other centralized scaling approaches out there.

If we take all these issues on privacy, trust on miners, media etc for granted then you are not in agreement with the privacy and security model of bitcoin made possible because of full nodes.
I think you are now somehow agitated by the previous embracing post of the fake Asterisk id, aren't you? it is what they do, they trigger anxiety and push buttons, be careful.

Bitcoin is what it is and presented in its white paper. The "Full-node! Full-node!" screams are fake and a canonical part of a made-up discourse. Bitcoin is dependent on PoW,  ways far beyond what they are presenting and it means there are lots of opportunities for utilizing PoW to help with crucial problems like the one I suggested above, without compromising a single bit of the security or decentralized nature of bitcoin as far as we are speaking of a world that game theory is applicable the way Satoshi has put it.

Alienating scaling/mass-adoption/decentralization proposals by spreading FUD about PoW is an alien discourse and has nothing to do with bitcoin white paper.
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
Asterisk,

Welcome back to the bitcoin discussion forum as a newbie, I was waiting for you and I hope you expect nothing less than full hiding here (just kidding  Cheesy)

Meanwhile, please behave and do not make an embracement out of this brand new id too. I know who you are, and I understand it is a shame for the bitcoin community to watch an important figure being humiliated because of his own reckless manner of debating. I understand too, it is hard for you to get rid of your own malicious discourse. But come on, just give this fake id a shot and think out of the box if you may.
 
I see no confusion in what you have quoted from me. It is crystal clear: Your claim about full nodes playing such a crucial role in bitcoin is simply wrong and baseless. As I've extensively discussed up-thread, full nodes have nothing to do with the network security, they are just useful for the entities who own them as a single body to keep them somewhat more secure against some attacks that are not considered realistic anyway.

So, I skip the embracing confusion part of your post if you don't mind.

UTXO commitments discussion
Regarding UTXO commitments, again you discuss these without understanding Bitcoin.

I'll share with you here that UTXO commitments are somehow similar to Ethereum 1's blocks' merkleized state snapshots.

What happened in the Ethereum community then was that, they fell for the temptation of validating blocks at all - when the Ethereum network is too busy, it will trig a feature that they call "fast forward", where a fully validating node will skipover one or more blocks, and thus simply blindly trusts the other nodes and the miners that they didn't forge anything. This is extremely risky and a viable attack vector for attacking their blockchain.

Further discussion of Bitcoin's security model, the definition of decentralization, and of that, here: https://hackernoon.com/the-ethereum-blockchain-size-has-exceeded-1tb-and-yes-its-an-issue-2b650b5f4f62
What is called UTXO commitment is radically different from Ethereum's snapshots. The latter is vulnerable to short-range attacks UTXO commitment is not! I read the article you've linked, the day it was published, good statistics about Ethereum but nothing new for bitcoin, the same blind enthusiasm about current bitcoin. Put some real meat on the table, please. Cheesy

In the scheme that I'm advocating for, nodes do not accept (and relay) a single block without full validation. Guys like you are worried about malicious UTXOs being forged by miners and committed to for hundreds up to thousands of blocks and exploited thereafter, which is really a stupid paranoia. It could also be considered a forgery of concepts to spread FUD about the mining scene of bitcoin for political reasons, again, stupid.

A 51% attack would not let through a double-spend
Last to respond to your question in the thread's title, "Is 51% attack a double-spending threat to Bitcoin?", I guess you have the answer already: It is not.
Why? According to you, it is because full nodes won't allow it but my argument is more solid: It is not gonna happen because it will be revealed anyways and destroy the attacker completely beforehand. Bitcoin inflation rules are currently parts of a social contract, rather than some lines of code, it is hard to understand but you should try.

Cheers,

legendary
Activity: 1876
Merit: 1157
Are we clear? This full-node, full-node propaganda is totally fake and misleading. It is not a campaign in favor of empowering bitcoin users by giving them an opportunity to run a full node, it is just a trick to relying less and less on miners in a baseless and paranoid way: Who in the hell can imagine a scenario in which miners are colliding for 3-4 days to inject a few false UTXOS in bitcoin blockchain? A paranoid or a politician.
I think this is again pretty much a question of what you think bitcoin is. A lot of people out there think a lot of things about what bitcoin is and there are claims from con-marketeers about "Real Bitcoin" "True Vision" etc etc.  If you feel that we CAN trust miners, media can be believed to disseminate trustworthy information, full nodes are not needed etc etc. then there are plenty of other centralized scaling approaches out there.

If we take all these issues on privacy, trust on miners, media etc for granted then you are not in agreement with the privacy and security model of bitcoin made possible because of full nodes.
newbie
Activity: 16
Merit: 4
aliashraf,

Your original question and discussion in your thread is a total mess. You are using very unclear terms, and you are bending Bitcoin terms in a way that shows that you do not understand Bitcoin's security model.

You don't understand what a "full node" is (as you confuse it with SPV), and you don't understand its role in the network.

It's a headache to read what you write as you appear to be ranting and make half-points all along the way.


Confusion..
Here is only one example of your confusions:
There is a very efficient, secure way of running a bitcoin full node on commodity mobile devices very efficiently in economic mode, called UTXO commitment.
Here is more confusion:
According to this model miners would have to commit to the UTXO (state of the bitcoin machine) by somehow including its hash in their blocks and a light full-node could besides synchronizing headers like a usual SPV wallet continue to downloading the full state of the machine as of latest couples of hundreds of blocks and act like an ordinary pruned full node thereafter. Right?

For this to happen, you need a simple soft fork which is not getting support, why? Because people are paranoid about miners being susceptible to commit to bad UTXOs for say 500 blocks!
Even more confusion:
Are we clear? This full-node, full-node propaganda is totally fake and misleading. It is not a campaign in favor of empowering bitcoin users by giving them an opportunity to run a full node, it is just a trick to relying less and less on miners in a baseless and paranoid way:
Even more confusion:
Who in the hell can imagine a scenario in which miners are colliding for 3-4 days to inject a few false UTXOS in bitcoin blockchain? A paranoid or a politician.

I started out reading your thread coming from a place of being willing to help and to clarify how Bitcoin works, but after reading your responses, I'm not convinced you are interested at all.


Bitcoin safe to double spend, based on fully validating nodes
Just to start somewhere, Bitcoin does solve the double spend problem. This is achieved by that participants run fully verifying nodes, and each such node enforce Bitcoin's consensus on every transaction of every block, and this will mean that in one node's view and perception, no double-spend ever occurs.

Miners are then free to mess up with blocks as much as they like, but they do so at their expense, so as long as the value of your transactions are insignificantly small compared to the Bitcoin miners' electricity expenses, you're safe - it's highly unlikely that someone will want to play appear-disappear reorg games with your 100USD transaction when it costs 10,000USD to mine a block.


UTXO commitments discussion
Regarding UTXO commitments, again you discuss these without understanding Bitcoin.

I'll share with you here that UTXO commitments are somehow similar to Ethereum 1's blocks' merkleized state snapshots.

What happened in the Ethereum community then was that, they fell for the temptation of validating blocks at all - when the Ethereum network is too busy, it will trig a feature that they call "fast forward", where a fully validating node will skipover one or more blocks, and thus simply blindly trusts the other nodes and the miners that they didn't forge anything. This is extremely risky and a viable attack vector for attacking their blockchain.

Further discussion of Bitcoin's security model, the definition of decentralization, and of that, here: https://hackernoon.com/the-ethereum-blockchain-size-has-exceeded-1tb-and-yes-its-an-issue-2b650b5f4f62


UTXO commitments infallible as you suggest is not correct
Your assertion that "UTXO commitments would always be valid because the miners are always attentive, correct and would never want to trick anyone" does not hold.

My take (which is a surprise somehow):
Unlike what is said ever and ever, one could put trust in miners as long as there is proof that:
  • Miners are not inflating the supply illegally,
  • The costs involved in defrauding him/her (personally) by re-org attacking the bllockchain are orders of magnitude higher than the assets he/she has put in stake.

Again, this reads confused, you need to be more specific and clear.


A 51% attack would not let through a double-spend
Last to respond to your question in the thread's title, "Is 51% attack a double-spending threat to Bitcoin?", I guess you have the answer already: It is not.


Asterisk
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
Relaying blocks is not a big deal. Your argument is not qualified enough to be discussed here, sorry, blocks get relayed anyway, e.g by collided pools.
I don't see how this part of your post is right. That is simply wrong, and I doubt you truly understand how the Bitcoin network works.
Blocks are relayed to any client, being a mining full node, a full node wallet, an SPV wallet, a blockchain explorer, ...) who connect to a pool/solo-miner and/or any full node that accepts inbound connections. What do you mean by accusing me of being ignorant about bitcoin relay network? It is not so complicated and I've been discussing it on many occasions in this forum.


How? Let's dive in:

There is a very efficient, secure way of running a bitcoin full node on commodity mobile devices very efficiently in economic mode, called UTXO commitment. According to this model miners would have to commit to the UTXO (state of the bitcoin machine) by somehow including its hash in their blocks and a light full-node could besides synchronizing headers like a usual SPV wallet continue to downloading the full state of the machine as of latest couples of hundreds of blocks and act like an ordinary pruned full node thereafter. Right?


If "that" doesn't validate and relay transactions/blocks, then it's not doing anything for the network, and therefore not part of the network.
"That" is an ordinary bitcoin pruned full node and does everything an ordinary full node can do other than uploading the ancient history of blockchain for the current (stupid) bootstrap process.
legendary
Activity: 2898
Merit: 1823

Quote from: Satoshi-Nakamoto-Bitcoin-WhitePaper

The incentive may help encourage nodes to stay honest.  If a greedy attacker is able to assemble more CPU power than all the honest nodes, he would have to choose between using it to defraud people by stealing back his payments, or using it to generate new coins.  He ought to find it more profitable to play by the rules, such rules that favour him with more new coins than everyone else combined, than to undermine the system and the validity of his own wealth.


That's the game theory.


That WAS the game theory BEFORE the cartelization of mining. Satoshi did not fully know future. How could the community express themselves if their ability to run a full node was taken away?

Nope. That is Plan B: What if "a greedy attacker is able to assemble more CPU power than all the honest nodes"?

"The community" would come here, start a topic and warn about the shit, it gets viral and the attacker and his coins are doomed in a few hours. Full nodes aren't helpful in most attack scenarios anyway.


The full nodes validates, that every transaction/block follow the consensus rules. If a miner mines an invalid block, it won't be relayed be the nodes.


How? Let's dive in:

There is a very efficient, secure way of running a bitcoin full node on commodity mobile devices very efficiently in economic mode, called UTXO commitment. According to this model miners would have to commit to the UTXO (state of the bitcoin machine) by somehow including its hash in their blocks and a light full-node could besides synchronizing headers like a usual SPV wallet continue to downloading the full state of the machine as of latest couples of hundreds of blocks and act like an ordinary pruned full node thereafter. Right?


If "that" doesn't validate and relay transactions/blocks, then it's not doing anything for the network, and therefore not part of the network.
legendary
Activity: 1456
Merit: 1174
Always remember the cause!
For the purposes of the OP, I'd say it's likely you are correct in the assertion that it's mainly game theory keeping that part in check.  But that shouldn't in any way be interpreted to mean we don't still need a healthy node-count.

We are arguing on the basic premise that having a healthy full-node count is a desirable situation or not. Your argument is that full nodes are useless in terms of keeping miners in check because the game theory will keep the rational miners in check. Those of us who think that full nodes aren't completely useless say so because  of two reasons:

1. Bitcoin network is equally a network of users/ businesses running full nodes that validate and propagate well-formed transactions, which of course is the only thing they can watch out for and not double spends. (You said in reply to @Wind_Fury that block propagation is not an issue. Is it because in a hypothetical 'miner-collusion scenario' propagation will any way happen between their own full-nodes over relay networks like FIBRE ?)
2. Having this network of full nodes is the best way to remain vigilant. If we depend on, say, a few guardian nodes and then media to keep the game theory going then you are again dependent on centralized authorities as DooMad had been saying.

Keeping the ability to maintain and run full nodes should always remain a low-barrier activity not just because of fear of miner collusion/ attacks but because a lot of properties of bitcoin arise from it, namely decentralization and being your own bank, even in the D-day situations, even if media becomes dishonest, even if a concerted attack targets miners in some jurisdictions rendering the miners disconnected. If we just accept that all of this is paranoia and in reality, such attacks are not possible then of course there is no need for full nodes.
 
couples of hundreds
Home miners plus full nodes is not a backup plan for D-day, it is the original plan which failed in 2011-2012 after pooling pressure falw showed its power and pools started to dominate the mining scene of bitcoin. Since then we are running plan B: Centralized mining, no home miner, less full nodes AND game theory.
Thanks for the link to your topic on PoCW. It aims to solve the problem of pooling because i guess you do believe that centralized pools can coordinate and they reduce decentralization.(??) Yet, if miners are to be trusted and no full-nodes are needed then doesn't that create the same problem?? Huge mining farms can coordinate. Instead of debating about need of full-nodes, i will go and read about these proposed scaling solutions you think are being ignored due to the love of full-nodes..
I think there is a deep, deep, misunderstanding: Actually, I am the one who is in favor of having millions of full nodes and the guys like @DooMAD and @Wind_FURY are the ones who are against it, practically!  Cheesy

How? Let's dive in:
There is a very efficient, secure way of running a bitcoin full node on commodity mobile devices very efficiently in economic mode, called UTXO commitment. According to this model miners would have to commit to the UTXO (state of the bitcoin machine) by somehow including its hash in their blocks and a light full-node could besides synchronizing headers like a usual SPV wallet continue to downloading the full state of the machine as of latest couples of hundreds of blocks and act like an ordinary pruned full node thereafter. Right?

For this to happen, you need a simple soft fork which is not getting support, why? Because people are paranoid about miners being susceptible to commit to bad UTXOs for say 500 blocks!

Are we clear? This full-node, full-node propaganda is totally fake and misleading. It is not a campaign in favor of empowering bitcoin users by giving them an opportunity to run a full node, it is just a trick to relying less and less on miners in a baseless and paranoid way: Who in the hell can imagine a scenario in which miners are colliding for 3-4 days to inject a few false UTXOS in bitcoin blockchain? A paranoid or a politician.

Pages:
Jump to: