28:43 For those who are not getting the same result when using online sha256 tools, the echo command is adding a newline character to the output, so the text isn't just what is in the quotes. If you write his command using echo -n, you will get the same result as online tools.
I'm wondering the following about "useful proof of work": Isn't the entire point of proof of work to attach an economic cost to mining? Mining costs electricity and the miner is compensated through the coinbase transaction. That makes complying with the network a net positive operation but makes misbehaving very expensive. If proof of work had some secondary use, the miner could "sell" the result of that computation making the mining process less costly which would defeat the purpose. What am I missing?
1:11:35 Did he just compare the energy wastage of bitcoin mining to the colonial exploitation of precious metals like that was a defense??? Am I crazy???
Question: all a 51 percent attacker would need to do would be to do his fraudulent transaction and rewrite the chain for a few blocks. After that all the other nodes would pick up from his longest chains. Correct? Meaning he wouldnt need to have 51 percent of the computing power forever- rather just long enough so that the rest of the network goes with it... is that right?
That's correct, after the fork becomes accepted, you could drop your compute power. There's no need to hold on, unless there's an adversarial party trying to fork you too :) On the notion of "holding on for few blocks": Do note that 51% only makes you marginally faster, and that it is still a stochastic process. Your next malignly placed fork might just happen to be one of those blocks that take an hour to compute while the benign people get a few lucky blocks, then you need to catch up with that with only a marginal speed difference. So there's still a reasonable chance that targeting the replacement of even a recent block requires pushing your own fork alone for many blocks, when the edge over the rest is that small. Of course, an attacked could get lucky too, and with a little more luck, they could succeed at a reorg even at
For 100 blocks. There's a maturity period before a block producer gets paid for their Proof of Work. So they'd have to win 100 more blocks without the network orphaning them.
I'm losing my mind here trying to replicate the hash at 28:59 online with a basic sha256 online tool and getting a completely different hash output... am i missing something?
I love the slides. They are easy to read, no distracting graphics, and the dark background doesn't burn my eyes watching it at night. You can tell he's a programmer with slides like these.