Quote from: AlexGR on January 26, 2018, 01:43:10 PM

Quote from: dinofelis on January 26, 2018, 01:27:17 PM

Quote from: AlexGR on January 26, 2018, 12:39:02 PM

Actors from outside the system that want bitcoin to die, can spam it to death - AND include the blocks on their own / at their own expense, because the cost of bitcoin back in 2010 was peanuts.

The point is that by PoW consensus, every previous block is voted over by PoW by the peer miners. So if the PoW consensus is working, you might think that even if a crazy attacker makes a 10 GB block that is correct according to the bitcoin protocol, the next miner should most probably decide NOT to build upon it because he estimates this not to be the good consensus of the bitcoin state.

But another miner might see that another block was issued as #xxxxx instead of the 10gb block and then reject that one for not building upon the 10gb one. So it's a gamble that others will do the same...

This is why this is a consensus decision. If a majority of hash rate thinks that the 10GB block is a good thing, then it will be included (as you say). If the majority of hash rate thinks that it is a spam block that shouldn't be part of the consensus, they will mine on top of the smaller block.

A miner can put a lot of considerations in his decision ; in as much as other miners agree with it, his decisions are confirmed, in as much as other miners disagree with it, his decisions are rejected.

Note that the risk for the second miner is also on his side if he mines on top of the 10 GB block. After all, the third miner may be of the same opinion as the first one, and think that such a large 10 GB block is not reasonable, and orphan the 10 GB block plus the second miner's block. So the second miner has to try to guess what is the most likely consensus decision that will be taken by the third miner. And so on.

Most probably, it was with this in mind that Satoshi introduced his 1 MB block size. When he introduced it, 1 MB was way larger than any reasonable block at that time, so it was a good "miner directive" to say that blocks larger than 1 MB should be considered as spam (given we measured blocks in KB at that time). It was a "good miners' directive" not a "protocol standard". The idea was most probably, in Satoshi's mind, to give a clear rule to the miners as what was to be considered "prohibitive spamming". It could systematically be put a factor of 100 or so above the "usual block size". It was a trivial formalization of the good practice "don't accept obvious spam in the consensus decision".

But then it became part of the "protocol of bitcoin" by some crazy narrative.

It is important to realize that in mining, there's no "accumulation of success". At the point that the second miner receives the small block from his peer, even if he was already mining (without success) on top of the 10 GB block, he doesn't lose any opportunity from switching to his peer's smaller block. It is not because he has been mining for 5 minutes on the 10 GB block that his chances are bigger when he continues to do so.

But on top of that, chances are that he has faster the full small block of his peer rather than the 10 GB block, if his network connection is of limited capacity. So from the moment that 10 GB is a network issue, *in any case* it will arrive late at the miner's place.

So there are enough arguments to say that there's no reason to expect that the block chain could have been spammed by gigantic blocks: miners would sensibly reject them in their consensus decision, and those blocks pay already a penalty because they lose time in network transmission.