Show Posts
Hi world! 
Please, need an answer for a very tricky question - if a bitcoin price falls much and miners will quit, the mining difficulty should fall.
Does this mean that it will become easier to attack the whole bitcoin system? (the whole amount of calculations need to be made will decrease as long as mining difficulty decreased).
Sorry of not the right forum branch!
Please, need an answer for a very tricky question - if a bitcoin price falls much and miners will quit, the mining difficulty should fall.
Does this mean that it will become easier to attack the whole bitcoin system? (the whole amount of calculations need to be made will decrease as long as mining difficulty decreased).
Sorry of not the right forum branch!
At this moment, the total hashrate is 19500 Ph/s.
In order to perform a 51% attack, you'd need a mining farm producing ~10.000 Ph/s, that's 10.000.000 Th/s
A single antminer S9 hashes at 14 Th/s.
So, you'd need about 700.000 S9's to perform a 51 attack right now.. The diff would have to drop a whole lot before a 51% attack is feasible.
That's what i mean - i guess that current hashrate is high due to high btc price. But IF price falls 10 times (for example), lots of miners (for ex 80%) will quite. then just 150 000 antminers will be enough (we should keep in mind the quited number of miners, they will be happy to get rid of the wasted equipment)
Another thing - when all the bitcoins will be mined, of course the hasharate will decrease greately. How then the attacks will be prevented?
In theory, you're right... In case of a 80% drop 150.000 S9's will be sufficient... However, buying, setting up, running and maintaining 150.000 S9's is a collosal (and expensive) task. I mean, even after setting everything up, the power draw of such a mega farm would be enormous...
The price of 150.000 second hand antminers would still be over 10 million USD (my guesstimation), you'd need thousands of racks, you'd need special serverrooms with cooling, tech guys, cabling,... Just to be able to perform a 51% attack. A 51% in itself is also limited regarding the amount of history that can be rewritten. Even if you controll 51% of the hashrate, i don't think it would be wise to try to re-mine the last 10 blocks...
My point is: i think it would be pretty obvious who is executing a 51% attack if this person hash to spend multiple millions and dozens of tech guys to setup his infrastructure. I think that at this point, most people *might* have chosen the path of an altcoin that doesn't use sha256d as it's POW algo.
If word gets out that somebody untrustworthy might be preparing for a 51% attack, i guess most people will switch, lowering the bitcoin price, lowering the FIAT equivalent amount of BTC the attacker can effectively steal, making the whole endaveour even less profitable.
As for your second question: i don't know what will happen after all coinbase rewards are claimed. The theory is that bitcoin will be so valuable that miners will earn enough from mining fees. In reality, the reward halves every ~4 years anyways, so i think that sooner or later there'll be an equilibrium anyways. In my opinion, it won't take another 3 halvings before the income from collecting fees outweighs the income of the block reward anyways. Combine this with innovations on the ASIC front, changes in the protocol, regulation or deregulation, banning, changing electricity prices and it becomes completely impossible to make a prediction about the future of mining.
So i guess there is no point in organizing such attack because if it happens, it will destroy all the value of the whole Bitcoin system.
I understand the idea about millions of dollars for a equipment buyout (though i believe that for already repaid investment in equipment the selling price might be even less than 1000 dollars).
But what about electricity consumption?
Also you say about limitations regarding the amount of history that can be rewritten, what do you mean? As far as i know there are (or at least were) no such limitations. so all the history theoretically can be rewritten.
Speaking about equilibrium between reward and fees - that's possible, but the bitcoin will may become so valuable, that the fee will be too high for costumers to continue use bitcoins as a payment system (its original purpose). Than the price will more and more depend on the necessity to return investment in mining equipment. it will go higher and will fall after all coinbase rewards are claimed. And so on and so further.
Also another idea - how can we be sure that if this attach happens and one will be able to obtain some crypto gold, the rest will drop off it? it will still bitcoin, and its fame is spreading fast across the world, so maybe some investors will still try to hold it.
