I am unable to actually get my head across the empty block factor. I do not see the purpose in doing that. If an empty block goes onto the chain, it should nonetheless comprise the hash of the earlier block, and the subsequent block has to comprise the hash of the empty block.
All an empty block would do is trigger everybody who’s mining to should restart mining once more as a result of the hash has modified. The rogue state would even have to begin mining from the present block too.
However as I perceive it, each transaction within the block can be signed by the proprietor of the pockets with their secret key. So they might solely forge transactions if that they had entry to everybody’s secret key. I could possibly be quick sighted right here, however the one factor {that a} 51% assault can obtain that I see is reversing transactions (by publishing a block-chain that ignores the unique transaction). If that they had 51% and will beat the community to publishing transactions they might money of their bitcoins, obtain the fiat cash or items, then return to the block earlier than their transaction and mine a brand new block with out their transaction printed.
It is one of many causes they are saying it is best to wait as much as 7 blocks to substantiate one thing is actually, really locked in. To undo that, the rogue state with 51% processing energy would want to begin from 7 or 8 blocks again and begin mining blocks till they’ve extra blocks than the present chain. The unique chain continues to develop, so it turns into a race for the rogue state. They should catch up, then over-run the unique chain. The protocol dictates that the LONGEST fork of the chain wins. So that they should overtake it, after which I presume announce to the community that they’ve rejoined. Everybody then sees they’ve an extended chain that begins from that seventh or eighth block again they usually settle for it because the king.
To carry out this assault, not solely do you want greater than 50% processing energy however you additionally want to make sure you keep forward of the processing energy. You possibly can have 51% however then a bunch of energy is added to the 49% and the stability has gone from 51:49 to 48:51.
Additionally, I’m not 100% positive however there may be the mechanism to extend complexity when blocks are found too rapidly. It is not modified typically from reminiscence but when the common block creation is lower than 10 minutes then complexity will increase to make it more durable. I feel this mechanism can be ingrained within the rogue states chain as properly so whether it is trying to carry out this over a protracted interval there could also be a problem with the complexity not matching as much as what it ought to and it could possibly be rejected by the community when becoming a member of.
All thought-about I do not actually have a lot information of the workings of Bitcoin however I joined right here to ask a number of questions and felt like I had one thing to contribute right here, so I hope that helps. Take it with a grain of salt.