Bitcoin Forum

All you need is 10% to 20% of hashpower.

What you do:
Shortly before an anticipated natural (or forced by selling) decline in hashrate you put your extra hash on BTC to make difficulty go up.
Now you sell off massively or use natural dynamics to your advantage. Once the miners drop out (10% to 15% of the network is enough) you withdraw your extra-hash from it.
Result: bitcoin is stuck at high difficulty as it retargets only every 2016 blocks. Blocks could take hours to solve. This will cause a further decline in value and people selling off as soon the news spread (selling can be reinforced at this point by the attacker) which in turn will lower hashrate until solving blocks takes so long the next difficulty adjustement can't be reached. Basically bitcoin remains stuck at high diff and with no network.

So if someone wanted to destroy bitcoin he just needed to find a way to collapse hashrate by 30% to 50% which can be easily done with a combined strategy of:
-providing parts of the hash yourself to cause higher difficulty and to be withdrawn later
-using anticipated natural decline
-selling coins in massive amounts

it's cheaper and more effective than any other attack. Every government or bank can do it.

Every time a decline in hashrate would be anticipated this attack becomes possible. (like right now - this exact attack could actually be on its way as we speak)


reference:
https://bitcointalk.org/index.php?topic=912190.0

sure. They don't want to adress it though.

Pumping up the price before and then dumping it would also help.

If you would additionally spam the network with microtransactions it would be defunct immediately.

The tech is much more fragile and totally not as secure as people like to think especially bitcoin with his old design. This wouldn't be possible with most altcoins as they have faster difficulty retarget. Bitcoin is much more vulnerable to these attacks than any of the newer, more advanced alts.

10 to 15% increase of 10 minutes is not 'hours'.  It is in fact 11 minutes.

10% to 15% is what you directly control. It's about controlling hashrate indirectly with priceaction aswell as using natural movements which can easily amount to much more.
The point is: it's actually possible to force a drop of hashrate of 40% or more by pumping it artificially before a natural drop would occure.

The attack consists of many components and needs good timing but would end bitcoin on the spot.

needs quite some recouces but would be much more fatal than just a 51% attack
And it's cheaper than 51% for sure.
Shocking stuff.

Explain again your "hours to solve" part.

for the same difficulty but half the hashrate will just mean blocks take double the time to be confirmed. so indeed we will end up with a slow network but not to the extend that it is unable to recover. Anyway this will only happen if the price of bitcoin crashes but if this becomes true then there is no value in bitcoins thus no need to employ your method to crash the bitcoin network.

hashrate drops on high difficulty by a considerable amount. The remaining miners now need much more time to solve blocks. Read up on what difficulty and difficulty retarget is.

i think this is a false assumption as diff should be calculated with another algo

would you be able to explain this further?
outputs of good hash functions can be accepted to be a uniform distribution

no this would not work and it would be wasting money for nothing.

https://en.bitcoin.it/wiki/Difficulty


can you explain why?

That wouldn't end Bitcoin. It might make some trouble, but even that wouldn't that big.
Even if you could drop the hashrate 50%(which is complete bullshit, since if it drops miners with older hardware just go in again), that just means double confirmation time. So what? It adjust after 4 weeks instead of 2 weeks, big deal ...

why would miners with old gear go in on high difficulty? The hashrate doesn't make a difference for them, the difficulty does.
Well, we assume a further decline as time passes eventually leading to everyone drop out.

Price fall, mining even more unprofitable for the reason of low price aswell as long blocksolving. It's a chainreaction that just needs to be properly started.

And there you are wrong. The overall hashrate tells them if they find the block or somebody else finds the block. The difficulty just tells them how long it will take them(or someone else) to find it.
Why would we assume a further decline? Everybody knows, that there will be a new adjustment in 4 weeks max.

the situation would be: high difficulty stuck and low hashrate
clones of bitcoin died this way before so it's actually not new.
What makes it possible is the long times between difficult adjustements.

The Bitcoin network is much stronger than that of his clones. You can't really compare them.
There are even people in the network, who still mine for the fun of it or just to support Bitcoin, not to make a profit.

sure. The way presented here makes it affordable though.
The few hobbyminers left will not want to mine if they can't even find a block in a day.
Clones is just smaller scale and happend on accident (or not) with large hash being on and off.

Do you really think, professional miners would trash their expensive hardware, they can't use for anything else than mining, when the difficulty goes up? That would be pretty stupid from an economical POV.

Title needs to be changed to, "How to slightly inconvenience bitcoin by throwing 70 million dollars away"

no they don't of course. That's why the attack takes place at exact the time many miners close down due to being unprofitable anyways (on their own). But it says that in the OP aswell. Short: Anticipated natural decline of hash (due to being unprofitable) would be reinforced by the attacker.
The attacker uses an anticipated and predictable decline in hash (which would be happening without him doing anything) to his advantage.

I wonder, what such an attack would actually cost. I think, even if you have the money to buy it, the market might not be able to provide the hardware instantly.
Try buying 10% of all iPhone 6.

Do you really think there is more then 0.000000001% of the hashrate provided by people who mine at loss just to support bitcoin?

POW fanatics you are so delusional.

Yah I think you'd have to buy up 3 or 4 months of Antminer production or something.

this attack dwarfs a 51% attack by several orders of magnitude. Does this attack have a name or wiki-page yet?

Heh, hyperbole/math fail. I don't have to think, I know so. I have 0.00006% of the network running at a loss at the moment, wrong by a factor of 60,000 just for one guy running a few gh? You should be a politician. You're not even close to right if it was only one guy in the world still running a single AM USB miner.

Wat? 15-20% is now "several orders of maginitude" different than 51%?


Can we get some numerically literate commentary PUHLEASE.

not that i was aware of



mining doesn't make sense when you don't find blocks. You can mine all you want in that situation without finding blocks once it has gone down too far.

i was talking about the fatality of the attack which would be enorm compared to a little doublespend.
Do you even comprehend the topic or you just try to deny it without even looking at/understanding it?

What the guy means is total doomsday; and relatively cheap considered the possible successrate and impact.
To resolve this issue one would need to hardfork bitcoin and change difficulty retarget. It's a total vulnerability as it is now.

Well, although technically is possible but what if the fundamental on strong buying kicks in once you force the price down? Bitcoin will be too cheap which will attract buying and cause the price to go up again before the miners shuts off. Maybe we underestimated this factor.

OP, it's an outdated shitcoin, we know that. Why cry so much about it? Are you holding the bag or what?
It's a non-issue for every other coin. People telling you Bitcoin would be the only thing and can't fail obviously are detached from reality.
I think it's interesting but no big deal for crypto in general. It's a bitcoin-only issue.

Better diversify and stop crying. It's going down the drain one way or another.

people won't be buying when they can not transact it - they will sell instead.

If a transaction takes half a day you get huge overload on the chain too as everyone wants to transact. The thing once started is a chainreaction.
Slow blocks, long time to wait to get into a block with the tx, etc
The queue for transactions will be enorm with the slow blocks as all of a sudden more transactions need to be processed too. As was suggested spamming the network at the same moment with microtransactions makes sure it's imediately defunct and almost nobody will be able to transact. The very few who get lucky to get a their tx through will have to wait for hours.
And you know how it is: once the big selling is initiated it can go on for weeks - only making it all worse.

https://i.imgur.com/s8NR5QI.png

 ::)

Ohhhh, like the millennium bug, I'm seeing what you're smoking now.

just wait for it after that idiot posted it here. The enemy is reading it too. Last time in here some spam was suggested to attack the network and 3 weeks later it happened. Can't wait for this to be tried out. Will certainly be epic.

+1

Summer 2011, hashrate dropped off 33%, bitcoin didn't die.
January 2013, hashrate dropped off 15%, bitcoin didn't die.

of course. 40% to 60% would be problematic. But i see everyone is just busy denying without acknowledging it or looking for ways to resolve the issue. I think that's a dangerous notion too.
The constant denial by the fanboys of everything that threatens their ability to find the greater fool to sell to as fast as possible is another strong reason not to be invested in btc too much. Just too much denying of facts

This is what a solution does not look like:
http://www.askingsmarterquestions.com/wp-content/uploads/2012/08/Ostrich-man-head-in-sand.gif

the problem is not new and the solution is developed already. All i did was combining known vulnerabilities to a bigger picture showing some risks which many didn't even know were there.

if you would DDOS some larger pools at the same time and would be able to at least temporary take them down this could be a ride.
Getting better by the minute.  :P

Don't say it wouldn't be possible for a rich individual to turn the killswitch with an orchestrated attack because it is.

if 1 block takes 10minutes to solve and the hashrate dropped 50%, this would mean a block would take, what 20 minutes to solve?

so lets just say that bitcoin network dropped 80% of it's hashrate, how long would it take the network to find a block and process transactions?

Still faster than WU or my bank for sending value to the other side of the world.

i do not see your apocalyptic scenario killing the bitcoin network

So, let's look at the counterarguments again:

- you can't just buy 15% of the hash rate
- miners wouldn't just shut down and make an even higher loss, because the bought costly hardware they now don't use.
- even in an event of 50% hash rate loss, that just means 20 min for a confirmation and 4 weeks for an adjustment and than it is back to normal

The only argument you bring in here is some kind of network effect, but you just can't predict, how other actors would react.

Should I be prepared for an assault by dragons too? I mean, as long as you're accusing me of sticking my head in the sand when confronted by purely imaginary risks?

So, what? Pools don't actually have any hashing power. People go to another pool. Just another scenario, where there is just a short disturbance.

some potent stuff here. You guys are pretty wicked though cooking stuff like this up.

The denying bagholders is just normal. I consider it 'noise' at this point.



depends on who you are

A very short disturbance, mining software lets you set failover pools, pretty much every miner is set up with them, can't contact pool for a few seconds, NEXT!

Oh, I forgot about that mighty wizard living in this big dark castle.

What about my other arguments?

i think one shouldn't be too sure about things because being too sure about oneself greatly increases the risks to be caught off guard.
The attack pointed out here is not easy to carry out but in case it would be successful it would be the end of bitcoin. I've also not seen it in this form before and the combination of these different attacks makes it quite potent.
Talking it down to the point of denial is always a good strategy  ::)    (not)

So, please tell me, who can buy 15% of the hash rate, in what time schedule? It's not like, I go in the store and say: "Here is 1 billion dollar, one 15% of Bitcoin hash rate, please".

Still, nothing about my other counter arguments.

if i was a gov or a central bank i'd probably get all the hash i wanted. If nobody would deliver to me i would have the recouces to build my own asics. Does this even need to be explained?

other arguments are false very likely. The claim 50% drop would cause 20 minutes blocks is likely wrong. I'd think they would take much longer.
Let's ask the other way: at what hashrate loss would a block take 3,10 or 12 hours to solve?

So, they would compete with all the other ASIC-developers.
You can't enter a market as a newbie and become one of the big players in a short time.

I'm sure a government can hire their experts. This discussion becomes tiring.

lol. rly. its math boy.

So, you are sure. That is really convenient.
That is just another way to say, you have no idea what you are talking about.

Go ahead and make a list of costs and constraints (manufacturing, logistics, etc.) for achieving 15%.
Please, take into account the time necessary to build these 15% (currently 50 PH/s) from scratch; and your actual hashrate share by the time you're done...
Finally, make a list of actors that could meet those costs and actually be able to achieve 15%.

to answer your question:

if you want ~3h blocks you need to bring the hashrate down to only: 5%
if you want ~12h blocks you need to bring the hashrate down to only: 1.4%

good luck with that.


the more interesting (and hypothetical) part is: what happens after the difficult adjustment, after all the hashpower comes back at a very low difficult :P

Please, go ahead. Here are the basic formula :

target_hashrate = DIFFICULTY * 7.158278826666667 # target hashrate (MH/s)
actual_hashrate = target_hashrate * (600 / TIME_PER_BLOCK) # hashrate for a block that took TIME_PER_BLOCK seconds to solve (MH/s)

This is what people say when they have ran out of facts or analysis to back up there claims, fuck the math & facts, send the bogey man in

what happens after they come back at low diff should be the next 2016 blocks will be mined very fast. So 2 weeks of mining in maybe a day or two (depending on how big the difference). So actually everyone would mine like mad in case the attack doesn't kill it, right?

This is certainly more interesting now.

I'm very sorry to inform you that due to a very large dump of stupid on this forum of late, it's currently worth nothing, not even the usual 2 cents. Maybe you should save it up in a cold wallet for a while.

someone should at least try it just to make sure

... And don't forget to account for the time and money required to build a leading semiconductor fab. And the requisite wafer manufacturing facility. Nevermind that the production of all the significant inputs of required unique equipment is watched closely and reported by trade magazines. This just cannot be done in stealth.

Yes, this is a known vulnerability. Indeed, several alts have been tanked in this manner. However, it was done with several times the previous hashrate, not a fraction.

Inconvenience, not fatal wound. OP needs to rethink the magnitudes involved.

Go for it.

The reason this could be done, is because 100s even maybe 1000s of times the equipment for that hashrate existed outside of those altcoins. Even before bitcoin was on ASICs it would have been extremely difficult to round up as many GPUs as bitcoiners were using at the time, and that was a device that had general purposes, like gaming, and was being used for scientific computation in some larger supercomputers.

So, there does not exist a significantly large amount of SHA256 hash power outside of the bitcoin network, there's a percentage on some SHA256 Altcoins, there's some old avalons that suck 10 times in electricity what they make in bitcoin, you could buy up every single one of those, blackout a decent sized city trying to power them up, and probably not even be able to pick them out from the noise/luck variation on the network hash graph.