Topic: Question regarding the role of miners vs nodes in securing the network - page 3. (Read 487 times)

It depends on what type of malicious activity we are talking about.

If we are talking about a malicious actor with the intent to destroy the Bitcoin system at any cost, then you are correct. The entity with more than 50% of the global hashpower can do that regardless of what the nodes can or can't enforce.  This would be a VERY expensive attack, but is theoretically possible.

On the other hand, if we are talking about a malicious actor with the intent to profit from their power, then the entity with more than 50% of the global hash power is MUCH more limited in what they can accomplish.  Any action that would destroy trust in the system as a whole would simultaneously destroy their ability to profit from it.

And why would the bold part be important? It seems insignificant to me. The word “merely” should be meant ironically here. If they can “merely” censor transactions, they can also delete the whole transaction history and make the whole system useless.

Yes, they indeed cannot force anyone to change the total amounts of coins ever issued, or increase their wealth from other people's money, but they can force the nodes to accept their defeat; to accept that their system is no more secure; that they essentially dug their own holes with the rules they all agreed to follow.

OP, the bolded part is a very important point. The miners that have successfully controlled 51% of total network hashing power still cannot spend coins that they do not have, or “print them out if thin air”, or send invalid transactions/blocks, or change the rules. They can merely censor transactions.

If you were to acquire 51% of the total computational power, it'd be enough for you to attack the network. You don't need 51% of the nodes, you just need one node who'll broadcast the chain with the most work.

No, they couldn't, because that would make it susceptible to censorship. The nodes just verify what they receive based on the consensus rules they follow. They can't deny a chain if it contains more work than the one they follow. Even if the blocks are empty, even if there are transactions reversed in prior blocks.

The whole system relies on the fact that there'll be honest miners outpacing anyone who'll try to attack it.

Hello everyone,

Recently, I've been reading a lot about how the bitcoin governance/development process works.
I read the book "The blocksize War", and one thing that caught my attention was how central in the blocksize debate was the role of miners vs nodes.

So I've been trying to understand what's the role of miners vs nodes in securing the network, and I have a couple of questions/doubts that I'd love to get answered.

As far as I understand, miners are in charge of confirming transactions, they secure the network by making it costly to falsify transactions (create unforgeable costliness, as Nick Szabo would put it). On the other hand, nodes are in charge of validating, propagating, and keeping a copy of transactions, they make sure that miners act according to the protocol rules, not acting maliciously (i.e. introducing false transactions, or try to double spend).

My question is, in order to make a successful 51% attack: One would need to have 51% of mining power, 51% of nodes, or both?
For example, in the case that someone gets to have 51% of mining power, could nodes protect the network from that attack by not validating transactions? In other words, could the network be secure if the nodes are decentralized even if the mining pool is not?

IMO, in the answer to this question lies the key of what keeps the network decentralized.

I'm new to this forum. So I'm sorry if this question would better fit into another topic. In that case, just make me know and I will move it to the right place.