Pages:
Author

Topic: Majority is not Enough: Bitcoin Mining is Vulnerable - page 2. (Read 51045 times)

legendary
Activity: 2506
Merit: 1030
Twitter @realmicroguy
So you admit not knowing who the Bitcoin developers and the forum admin are and state that Bitcoin is "abandoned" a few posts apart?

What I said was, "Bitcoin's developer abandoned the project years ago and disappeared into thin air". I think this is a well-established fact.
legendary
Activity: 1050
Merit: 1003
In my opinion, bitcoin cannot survive if the US gov't decides to take the ax to it.

Don't you think that also depends on what the EU, Russia and China do?
I dunno. I guess I expect the EU to go along with whatever the US says.
I expect China to ban bitcoin if/once it gets really big regardless of what happens elsewhere.
I don't fell informed enough to speculate about the rest of the world.

Just to be clear i don't think the us will ban bitcoin. Say what you like i still believe that the us provides the world's leading environment for innovation. They are not so stupid as to fuck this up.
hero member
Activity: 714
Merit: 500
Martijn Meijering
In my opinion, bitcoin cannot survive if the US gov't decides to take the ax to it.

Don't you think that also depends on what the EU, Russia and China do?
legendary
Activity: 1050
Merit: 1003
What does this mean? It means that as long as bitcoin mining is a continuous process rather than a one time thing, then cooperating is the rational thing for miners to do (regardless of selfish mining and other such nonsense).

Thank you for your analysis. That's what I felt from the beginning about that "strategy". Miners do not care (so much) about the number of coins they get than about the number of stuff they can buy with them.

However, does it apply to someone who wants to destroy Bitcoin ?
Is it easier with this strategy than with a traditional "51% attack" ?
Probably. But it was never very difficult to begin with. Moreover there are other ways of destroying bitcoin that make much more sense.

Say I'm the US gov't out to destroy bitcoin.

Step 1) Make it illegal and start rounding people up. Watch price plummet.
Step 2) Buy up hardware and conduct 51% attack on the cheap to neutralize remaining participants. [Once price plummets the used ASIC devices will be very, very cheap.]

In my opinion, bitcoin cannot survive if the US gov't decides to take the ax to it. I don't think this is going to happen. I also don't think that it will make sense for a private actor to do this. (many different guys will benefit from burying bitcoin, but they are not going to be able to coordinate an attack aside from lobbying gov't. Going it alone and destroying bitcoin is not going to be sufficiently profitable to any one company to make it worthwhile.)

The bigger danger is the falling block reward. If this is not addressed, it will cause problems in the long term (i.e. say starting 10 or 20 years from now).

legendary
Activity: 1050
Merit: 1003
I wasted enough insomnia time on this that I thought it deserved its own thread.

https://bitcointalksearch.org/topic/cuniculas-rebuttal-to-bitcoin-is-broken-idiocy-327292

This is a mathematical explanation of why the article uses incorrect methodology.
I use the appropriate methodology (where a miner cares about the future value of his mining hardware) and show that their conclusion no longer holds.

Note: You may want to refer to the following wikipedia articles to help with understanding my argument.

http://en.wikipedia.org/wiki/Dynamic_programming
http://en.wikipedia.org/wiki/Subgame_perfect_equilibrium
http://en.wikipedia.org/wiki/Dynamic_game
http://en.wikipedia.org/wiki/Folk_theorem_(game_theory)

Well, to give you a flavor. Here is the single most relevant slice of the wikipedia articles.
Quote
For example, in the Prisoner's Dilemma, both players cooperating is not a Nash equilibrium. The only Nash equilibrium is given by both players defecting, which is also a mutual minmax profile. The folk theorem says that, in the infinitely repeated version of the game, provided players are sufficiently patient, there is a Nash equilibrium such that both players cooperate on the equilibrium path.

What does this mean? It means that as long as bitcoin mining is a continuous process rather than a one time thing, then cooperating is the rational thing for miners to do (regardless of selfish mining and other such nonsense).

Why is bitcoin mining a continuous process? Because miners own hardware and will be stuck with paperweights if bitcoin collapses. This ownership of hardware underpins the bitcoin incentive system. The hardware is essentially a proxy for proof-of-stake. I don't think people adequately understand this.  '

Note: An important takeaway message here is the deficiency of standard computer science approaches in analysis of bitcoin incentives. Typically, computer scientists will ignore things like incentives to maintain the value of hardware. This just doesn't seem like part of the problem to them. For economists (e.g. me), effects of behavior on asset prices is a standard part of the problem. You cannot analyze one part of the system in isolation from the other and expect to obtain a reasonable model of human behavior. It is quite shocking to me how much credibility this theory has obtained despite its obvious deficiency.

 
hero member
Activity: 896
Merit: 1000
This is nonsense. Bitcoin still has numerous developers working on it.

Let's just hope it's not the same developers responsible for keeping this forum running. J/K Tongue

So you admit not knowing who the Bitcoin developers and the forum admin are and state that Bitcoin is "abandoned" a few posts apart?

Obvious troll is obvious. Its ignore link color may change.
legendary
Activity: 1050
Merit: 1002
Another thing about those MBRNs...

Earlier in this tread in response to this quote:

...
Low latency connection itself is expensive, and we can nullify its advantage by relaying unverified block headers. People will always assume a block header is valid unless it is proven otherwise, and always mine on top of the first seen header. (I think creating invalid block header is very expensive and no one is trying to do this. Any stats for this?)
...

I said that broadcasting headers before the final set of transactions doesn't help because miners are never sure what block to mine on top of until they know the winning block. Trolling the network is possible by anyone with any size hash capacity and no worry about block reward.

That's still true, but a MBRN can add trust into the equation. When hearing of a block header from any random node one isn't sure of the rest of the block. Hearing of a block header from a MBRN is different since it's acting as a known source of good, verified information. It's worth the risk mining on top of only a block header then since a header which doesn't match up with the transactions sinks any credibility the MBRN has built up. As justusranvier points out propagation of block headers can be very fast, near instantaneous.

The real value of a MBRN is in the most effective use of hash-rate. It's almost always directed at the most profitable block, near zero waste. This appears to me to completely nullify the Sybil attack dynamic the paper counts as valuable to an attacker.
legendary
Activity: 2576
Merit: 1186
Even though it's a little taboo to mention, the truth is: Bitcoin's developer abandoned the project years ago and disappeared into thin air. If he was still around he would be actively evolving the coin and addressing issues like this one in a clever manner. Bitcoin without Satoshi is like Apple without Jobs.
This is nonsense. Bitcoin still has numerous developers working on it.

To my understanding, the only coin actively developing a 51% defense is Goldcoin whose developer is actively building upon Satoshi's unfinished work.
"51% defence" is nonsensical. As long as you're entrusting decisions to majority hashpower, someone with a majority is making that decision. If you're not doing that, then you're throwing out the entire innovation that Satoshi solved with Bitcoin, and your solution has nothing at all to do with Satoshi.

I'm not saying it's a bad idea to try to solve double spending some other way, just that it's not where Satoshi was going with Bitcoin.
hero member
Activity: 896
Merit: 1000
Even though it's a little taboo to mention, the truth is: Bitcoin's developer abandoned the project years ago and disappeared into thin air. If he was still around he would be actively evolving the coin and addressing issues like this one in a clever manner. Bitcoin without Satoshi is like Apple without Jobs.

To my understanding, the only coin actively developing a 51% defense is Goldcoin whose developer is actively building upon Satoshi's unfinished work.

You mean one of the coins that I blacklisted in my scrypt miners because my up-to-date node was on a forked branch? You have some balls to come advertise Goldcoin in this thread!
legendary
Activity: 2506
Merit: 1030
Twitter @realmicroguy
Even though it's a little taboo to mention, the truth is: Bitcoin's developer abandoned the project years ago and disappeared into thin air. If he was still around he would be actively evolving the coin and addressing issues like this one in a clever manner. Bitcoin without Satoshi is like Apple without Jobs.

To my understanding, the only coin actively developing a 51% defense is Goldcoin whose developer is actively building upon Satoshi's unfinished work.
legendary
Activity: 1638
Merit: 1001
Quote
I wonder if Cornell professors are accountable for lapses in ethical academic behaviour?

Take away five CS scholarships and ban them from College Bowl for two years. 
staff
Activity: 4284
Merit: 8808
Call me old fashioned but I thought a research paper normally involves research (here: discourse with core dev), and also involves peer review before publishing. Or has Cornell abandoned such archaic practices?
On the subject of Bitcoin fairly few academics have bothered to communicate with the experts in "industry" (e.g. core devs, folks here posting with books-badges, etc). It's a shame: the failure has resulted in a lot of really confused papers which could have been very easily improve a lot with some expert pointers.

But there are a lot of broken things out there— e.g. no ethical review on experimentation, etc. (I loved one paper I saw that said something like there was no ethical concerns with their live fire privacy attacks on the unwitting public "because anyone else could have performed the same attacks").
legendary
Activity: 1078
Merit: 1006
100 satoshis -> ISO code
I am an academic myself and I think telling people to sell their bitcoins definitely crosses a line when it comes to intellectual discourse.
I wonder if Cornell professors are accountable for lapses in ethical academic behaviour?

Call me old fashioned but I thought a research paper normally involves research (here: discourse with core dev), and also involves peer review before publishing. Or has Cornell abandoned such archaic practices?
legendary
Activity: 1400
Merit: 1013
I am an academic myself and I think telling people to sell their bitcoins definitely crosses a line when it comes to intellectual discourse.
I wonder if Cornell professors are accountable for lapses in ethical academic behaviour?
legendary
Activity: 1008
Merit: 1000
Here is the tweet about selling bitcoins: https://twitter.com/el33th4xor/status/397219415025934336

It is clear now they are not acting in good faith. Apparently they have no idea at all there's something wrong with their extreme arrogance and spreading factual lies and FUD.

They can't even get their lies straight between the two of them - https://twitter.com/el33th4xor/status/397827176759697408

Wow. I really liked the paper when I first skimmed through it and I even sent a nice note to the authors... but that was all before the Business Insider press releases and this. I am an academic myself and I think telling people to sell their bitcoins definitely crosses a line when it comes to intellectual discourse.
donator
Activity: 2058
Merit: 1054
Here is the tweet about selling bitcoins: https://twitter.com/el33th4xor/status/397219415025934336

They are not acting in good faith. Apparently they don't see a problem with their behavior.

They can't even get their stories straight - https://twitter.com/el33th4xor/status/397827176759697408
legendary
Activity: 1050
Merit: 1003
So these two guys at Cornell University, an associate professor and a post-doc, publish a paper on Arxiv about what they believe to be a flaw in Bitcoin.

Rather than quietly and tastefully wait for some feedback on their ideas, the professor immediately Tweets "You heard it here first: now is a good time to sell your Bitcoins."  He then proceeds to blog "Bitcoin is Broken."  News outlets, seeing no reason to believe two guys with PhDs employed by prestigious Cornell University are spraying FUD with a large diameter hose, run with the story that a fatal flaw has been discovered in Bitcoin, and its collapse is iminent.

The central thesis of his paper is that you can make mining slightly more profitable by picking when to make public blocks you have mined, and that this will cause miners to join your pool until it increases to a size which threatens the decentralized nature of the Bitcoin cryptocurrency.

Now we've discussed the threat posed by large mining pools for years, and it makes little difference whether they attract clients by gaming the mining protocol, paying a premium for shares, promising a share of the windfall profits that result when they reach 51%, or giving away free toasters.

It is generally accepted that such shenanigans would be noticed by the community before any harm was done, and appropriate policies adopted.  Therefore, it is unlikely people will make the investment to try such things, only to have them nipped in the bud forthwith.

The professor reacts to skepticism about his attack by saying that all rebuttals must "include math" to be seriously considered, and goes on and on about the great burden he endures by having to put up with the stupid.

He deletes critical blog comments claiming they contain "profanity," which apparently includes the word "fraud" and Will Rogers quotes.  After a few days of being slow-roasted on the spit of Bitcoin community displeasure, he defiantly declares" I used to think that money brought out the worst in people, until I saw Bitcoin."

The reaction of the developers to the idea that this attack poses some serious real threat to Bitcoin has been somewhere between "yawn" and "snooze."

Now the paper is interesting, and it has resulted in some serious discussions about how such an attack might play out, although there are some questions whether the methodology is a perfect fit to the problem being described.  Had it simply been released without the accompanying egregious self-promotion and predictions of Bitcoin demise, it probably would have been warmly received, and constructive feedback cheerfully provided.

This whole scenario is like a guy walking up to show everyone a marvelous anti-gravity car he has invented.  He describes the engine in detail with complicated fluid dynamic equations and state diagrams, and refuses to entertain any rebuttals of his design methodology which don't use these tools.  Meanwhile, a less technical crowd has gathered, and noticed there is no hose connecting the engine to the fuel tank.



 

This sums it up nicely, particularly the paragraph in bold.
hero member
Activity: 896
Merit: 1000
So these two guys at Cornell University, an associate professor and a post-doc, publish a paper on Arxiv about what they believe to be a flaw in Bitcoin.

Rather than quietly and tastefully wait for some feedback on their ideas, the professor immediately Tweets "You heard it here first: now is a good time to sell your Bitcoins."  He then proceeds to blog "Bitcoin is Broken."

Wow, I didn't know about the "sell" tweet. I had to check on Twitter to believe it (and found lots of damage control and whining in the process).

After publishing a supposed security flaw without contacting the devs first which is already amateurish at best, the "sell" tweet now makes the professor suspect of having an agenda.
Even if his intentions weren't dishonest his public life is now checked under the microscope by hordes of people with various motivations. I wouldn't want to be in his position right now especially if he has anything to hide. Go easy on him people: with the way he is currently handling his paper he begins his career with quite an handicap already...
legendary
Activity: 3066
Merit: 1147
The revolution will be monetized!
The "exploit" he "discovered" has been discussed in 2010 on these very forums.
Indeed, apparently Satoshi also considered it. And, if I'm not mistaken, it is a modified "Sybil" attack. Which is also known.
sr. member
Activity: 336
Merit: 250
Rather than quietly and tastefully wait for some feedback on their ideas, the professor immediately Tweets "You heard it here first: now is a good time to sell your Bitcoins."  He then proceeds to blog "Bitcoin is Broken."  News outlets, seeing no reason to believe two guys with PhDs employed by prestigious Cornell University are spraying FUD with a large diameter hose, run with the story that a fatal flaw has been discovered in Bitcoin, and its collapse is iminent.
Based on his behaviour over the last few days, I give him an 8/10 for douchebag.

He's eligible for a perfect score if it turns out he posts on this forum as "revans" and if he's in any way related to the DDoS attempts on the exchanges and charting sites yesterday.


You are an idiot.
Pages:
Jump to: