Topic: Bitcoin's kryptonite: The 51% attack. - page 3. (Read 27720 times)

Uh, comrades?

The existing computing power of Bitcoin is 61 PFlops. To execute such an attack, wouldn't someone need ANOTHER 61 PEtaflops?

Well


I'm a bulldog for Bitcoin. I get a bit suspicious when the topic moves faster than those participating in the discussion. I do apologize. It'll probably happen again. I'm very defensive of this community. They've proven themselves.

And I don't expect people to work for me. I'm putting in drafts for plugins, loans, community building just like everyone else.


cue Harvey Keitel in Pulp Fiction: Pretty please with sugar on top.


The future of this network is worth at least a million times that. Cya tomorrow.

Dude, first of all, I like technology, but I am not precisely a programmer.

Second, you insulted me for nothing a couple of posts ago, and you expect now that I work for you? For starters, you should learn to be polite, and then buy me a couple of beers, or send me the bitcoin amount of those beers, preferably adding the price of a pizza too. Only then could we start taking about business. 

Ok, its late here, I logout for today.

Tell you what, help me get a draft of my towncoin (forkless because the difficulty / block reward is heavily yoked down) modification as a plugin. I only want to make it optional. The whole machine crumbles if we apply the possibilities. Due to the sharp reward drop the square root is necessary as a stretchy ratio rather than the hard drop.

Three new bitcoind options:
--accept_dynamic_difficulty_blocks
--enable_dynamic_difficulty
--enable_soft_gradient

The links are here:
Proposal: http://forum.bitcoin.org/index.php?topic=11541.msg162881#msg162881
Inception: https://github.com/bitcoin/bitcoin/issues/296

I'll have a pull request in the morning.

Couldnt agree more.

But social change is difficult in the current world. Thats why us geeks have so much hope in technology coming to the resucue. But I guess this time technology alone wont cut it. Lets find a hybrid solution. But I see lack of awareness in the bitcoin comunity of this shortcommings. Too much blind enthusiasm.

The final power is in peoples hand, the problem is that they give their power away to the system.

Which means that like CPUs much of their capabilities involve functions inefficient at hashing. This debate is about hashing power. Supercomputers are being outgunned.


Moving the goal posts again. Bitcoins in total are worth 2x that. The amount of capital necessary to create the bitcoin system is [X Tflops / (Tflops / Thash)] * (Cost / Thash).

For $4000 you could get 2Ghash/s using 3 6990s + PSU + cooling. So $8M for 4Thash/s. If a supplier offered GPUs in Bitcoins - the community could create a network 12.5x the size it is right now in a matter of weeks. Hell distributing the coins and GPUs to the BTC militia would be the bottleneck.

With my community modification (bet it's in the 2 digit range of lines of code) the bitcoin network would be back up and running in no time. An attack on the network would result in a major backlash and a huge strengthening of the network. At which point hashing speed would be ridiculous and BTC value would be even more absurd.

It's not a technology problem. It's a community commitment problem.


1 internet is worth 1000. Telecomix and Anonymous revived Egypt's Internet in days. A Bitcoin crash would only be a reboot. Nothing more.

Interesting statistics, although to evaluate a well organized attack on cryptocurrencies its not fair to compare supercomputers to Hashing GPUs, as they are made for very different purpouses. GPUs are really cheap dumb simple number crunchers. Supercomputers are much more expensive complex pieces of hardware to manipulate information.

The key point is compare the resources of each side. If the total combined mining infrastructure of the network is 50 million dollars worth, an attack is trivial. Even a country like Lichtenstein could beat our computing power. They would buy the gpus in the market, or sign a contract with China to build the GPUs over a period of months.

Really, there is no point in deluding oneself that a security system like Bitcoin based on brute hasing power is invulnerable. Right now Bitcoin is at the mercy of any small group of wealthy individuals that decided to attack.

Thats not necessary the end of the world. Most companies and groups in the world are in a similar position. But its important to be clear that Bitcoin is not going to change the power balance of the world without the consent of the establishment at this time. It can only survive if the establishment wants to. To me, right now, Bitcoin is just an extra layer of technology for our lives, that can make us early adopters rich, but that wont have any lasting impact in how this world is managed on a global scale.

Thanks, will check it out.

andes, the combined hash rate of the top 500 supercomputers can be seen here:

http://forum.bitcoin.org/?topic=7675.0

The total hash rate of bitcoin miners can be seen here:

http://www.bitcoinwatch.com/

Satoshi must have been trembling when he typed bitcoind getwork for the first time.

This thread is surreal. But hey if Bitcoin can survive an attack by the Minbari Empire, please go ahead. Check out my signature: first two links point to a quick and easy change that would allow millions to enter the network.

Thanks man! Will spend some time reading your suggestions.

And where are your statistics amincd? You did not answer my question regarding computing power. I am really interested in them.

Any links to these discussions?


You mean the people running the games? That wouldn't surprise me given there are millions of people playing 3d games. I don't see how it invalidates the point about the amount of hashing power that bitcoin miners have relative to supercomputers. Yes, cumulatively, gamers have a lot of hashing power too..


That's a good point, but it would have to be a variant not-dependent on proof-of-work, which leaves only one based on a decentralized PKI, which IMO is not feasible.


An attack is of course possible I just think unlikely. Point taken that dismissal of the threat doesn't serve the technology well. I'll also add that worrying about an unlikely threat could also be counter-productive by scaring people whose participation could help bitcoin's security.


It'll become readily apparent when people that the bitcoin community trusts say their transactions are not going through. There is a social element that is more important to bitcoin's security than the hashing power being contributed to it.


I'm not trying to cavalierly dismiss your concerns, I just don't think it's likely that the community can or will be corrupted by any likely attacker through bribery or other means.

Man you cant be serious.   As said, the game here is the allocation of worlds resources via the control of the monetary system. And you say that tens of millions of dollars is a lot of money?

To put that in perspective:
Do you know how many people have a net worth of 1 million or more in the US? 10 million people.
Do you know how many people have a net worth of 5 million or more in the US? 1 million people. A handfull of these could finance tens of millions of dollar.
Do you know how much one single F22 Raptor plane costs? 350 Million. Just one.  Source http://www.time.com/time/photogallery/0,29307,1912203,00.html
Or think about how much money drug dealing makes.
Or illegal arms trading.
And the list goes on...

cmon!

So far only an ideological attack is really a concern. Supercomputers would have to dump whatever they were doing and stick to hashing. Amazon won't do that. Google might and blame Anonymous for slow search speed.

And yes it is easy to detect. Sometimes a canary (a victim) is better detection than whatever gas sniffing nanobots (some scheme or other) we could put in the mine.

The web of trust on #bitcoin-otc is pretty good.

Maybe my forkless towncoin idea can be applied here.

yes. i recommend looking up the posting history of the user 'bytecoin' and, though i don't want to flatter myself, you can look up mine as well if you'd like. it may also be worthwhile, if you have time, to read all satoshi's old posts; they exhibit more perspective and nuance than the way they're commonly echoed in this forum.

ben laurie's discussion and the comments to it at his blog at http://www.links.org may also be helpful in general.

by all the calculations given in other discussions, it's not nearly that expensive. i'm pretty sure i have the resources to do it myself, if i were of such a mind. many small corporations could easily do it.


than bitcoin. many games are likely running the equivalent of more than a few thousand gpus at any given moment.


this is too glib an objection. what if the variant is not subject to that particular attack vector?

you seem to want a 'magic bullet' response to all my points, but there isn't one, and the search is in vain. instead, what matters are overall likelihoods. you can respond with a better theoretical threat assessment, but mere dismissal of attacks by this community is not going to serve the technology well.


pump-and-dump spam for a penny stock may cost a lot, but it can have significant gains from market manipulation if it escapes regulation. the same is true of many attacks on bitcoin.


and among the several possibilities, which of the complainers are 'honest' and which are part of the attack? by what (non-bitcoin, non-proof-of-work) procedure is meta-consensus reached? do we go by reputation in the forum? (if so, is that for sale, and at what price?) an attack like the overflow bug in october(?) would, if it happened today, practically be irreversible unless we want to give up a significant part of bitcoin's decentralisation. and a bug like that, if timed strategically by an intelligent market manipulator, could divest the currently prominent block chain of almost all its value.

Unk, thanks for your extensive, clear and organized information. It was the most comprehensive answer so far to my questions.

Could you point to other groups of discussion / forums / websites where I can find people discussing this issues, and/or developing sound bitcoin alternatives? I would love to learn more about this fascinating area. The nicknames you mention are mostly found in this forum?

Tens of millions of dollars for hardware, and millions more for manpower is expensive for most groups in the world.


What do you mean many 3d-games have more hashing power than the top 500 supercomputers? You mean 3d MMOG server farms? Do you have any statistics on this? I'd like to learn more.


What's unlikely about there being 10s of millions of computers that can contribute to the network by simply visiting a web-based miner using WebCL?


I think that's highly unlikely but it's difficult to provide any solid evidence for why. I think that an attack would be far more likely to come from a closed organization than a grassroots movement, especially a web-savvy grassroots movement who are the most likely group of people to share in bitcoin's ideals of allowing p2p monetary transfers without the need of going through large banking intermediaries.


A strategic attack would not be profitable because it would benefit not only the attacker, but the attacker and all competing currencies. If an attack is done by someone with a stake in a bitcoin variant, it would undermine the very concept and be unprofitable.


A strategic attack could certainly be valuable to someone for ideological/non-monetary reasons, I just don't see any reason to think it could be profitable.


People start complaining about bitcoins they received suddenly being unconfirmed.

i think your concessions, andes, were premature.

the oft-repeated statistic about bitcoin being the largest supercomputer or exceeding 500 others is silly and almost intentionally misleading. many 3d-intensive games are much larger 'supercomputers' on the same metric, as probably is the global dns system or smtp. it's a laughably bad piece of marketing that should be stopped because it makes bitcoin look foolish to anyone willing to see past the initial gleam of the claim. in the world of uncritical bloggers, it may not make much difference, but any legitimate journalist would research that claim and end up calling an academic computer scientist who would explain how misleading it is to call a group of a few thousand gpus 'the world's largest supercomputer'.

as to reserve hashing power, it's unlikely that there's a significant amount of it that could easily be deployed. and it works both ways: what stops an anti-bitcoin lobbying group (say, one that opposes some illegal site that uses bitcoin) from distributing an attack? there are relatively few people who stand to make fortunes from bitcoin, and there are many more who potentially benefit from an attack. i wouldn't want to play those odds; instead, i'd want to develop alternative mechanisms for proof of work that make cpus impossible to use as an attack vector. (gpus do this already to some extent, fortuitously. but they have other problems.)

for the record, i say all this as a strong supporter of the technology, albeit one consistently disappointed by the extremism in this forum and the unthinking defenses of bitcoin often offered. like anything or anyone we like, bitcoin has problems and is not perfect.