Well do you have an algorithm that make such attack feasible with less energy and time?  I may have one before the universe ends. Or I may have a better computer that consumes less energy. Good luck ECDSA -- like all crypto based on the discrete logarithm -- lives from the fact that there is no algorithm known to calculate the discrete logarithm efficiently. It is not proven to be hard. (Same is true for factorization by the way.) |
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Well do you have an algorithm that make such attack feasible with less energy and time? I may have one before the universe ends. Or I may have a better computer that consumes less energy. |
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How much computing power would be needed? Dunno, probably more than the total energy output of the sun for more than the age of the universe... That's a worthless statement, because it depends on current computing technology and ECDSA-attacking algoithms. |
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looks like it's time for a ddos...
Not necessary. As I stated: Don't panic. Having 50 % in a mining pool does not make you an attacker. |
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You would have to break ECDSA with 256 bit keys. If you could do that, you could do a lot more than cracking Bitcoin addresses.
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Yes, but listen. IT IS FIXABLE. And smart minds are working on it. It is only the current manifestation of the pool system that allow these pool attacks to work. http://forum.bitcoin.org/index.php?topic=9137.0It is possible to have pools work with zero pool attack risk. It is being worked on by smart people. The new system will probably be adopted soon (within 6 months). That thread hasn't been touched in the past month. Who, exactly, is working on this? The fact that this shit is still going on, combined with the ridiculously pollyannaish mentality of most bitcoin users, is seriously alarming. Maybe the best way is to create a open source mining software solution that is good enough to be adapted by mining pools. Everything else is doomed to fail, nobody can enforce mining pools to take care about security. |
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If you look at the number of US Dollars in circulation, and you imagine that those are replaced by Bitcoins, you get a value in the order of $50k per BTC. EDIT: Some hard numbers added: New York FED says: $829 billion in circulation. There will be 20999999.9769 BTC (if the decimal point does not change - else it may be a little closer to 21M). This makes $39,476.19 per BTC. And this means current USD! As the USD will inflate, the value per Bitcoin will rise alike. You seem to be forgetting that while the USD is only divisible up to 2 decimals (in hard currency, not talking about representations in databases), a BTC is divisible up to 8 decimals. A number is just a number. If you compared the amount of satoshis to the amount of dollar cents, it would suddenly look a lot different - while these satoshis would still be parts of Bitcoins. What do you want to say? |
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I really thank you for your effort, but I could not find any claimed flaw that actually looked like one - except maybe the obvious. But those obvious flaws are mostly the disadvantages of certain features. We can't fix them in principle if we want to have those features.
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If you look at the number of US Dollars in circulation, and you imagine that those are replaced by Bitcoins, you get a value in the order of $50k per BTC.
EDIT: Some hard numbers added:
New York FED says: $829 billion in circulation.
There will be 20999999.9769 BTC (if the decimal point does not change - else it may be a little closer to 21M).
This makes $39,476.19 per BTC. And this means current USD! As the USD will inflate, the value per Bitcoin will rise alike.
I Like the sound of that. It looks a bit small to me though. The figure I have come across is, if just 1% of online trade in the US were to shift to Bitcoin each coin would be worth $10,000 I think your figure is unrealistic. It is higher if you combine currencies, there are a lot of worthy Euros out there. But it won't be much more than 10 times the figure I calculated. |
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If you look at the number of US Dollars in circulation, and you imagine that those are replaced by Bitcoins, you get a value in the order of $50k per BTC. EDIT: Some hard numbers added: New York FED says: $829 billion in circulation. There will be 20999999.9769 BTC (if the decimal point does not change - else it may be a little closer to 21M). This makes $39,476.19 per BTC. And this means current USD! As the USD will inflate, the value per Bitcoin will rise alike. |
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Block header contains also merkle root which is unpredictable but everything else must be consistent.
You could ignore that, you don't have to accept transactions anyway. |
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I already gave it to you. Multiple times. "In the last ~110 minutes only 6 blocks have been solved (135104-135109)"
You are right, sorry. At least the average meets your requirement. |
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6 blocks in a row that require twice the time are not statistically insignificant.
Yes it is. It happens many times every single week. Check the timestamps on blockexplorer.com 6 times in a row? Show me a single example! The whole point of the 6-blocks-makes-a-confirmation rule is that the probability falls exponentially, and that with 6 blocks in a row it is practically impossible to happen. |
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Another detail is that with the half mining power you only get 3 blocks per hour because of the difficulty.
So you need 2 hours in the first place to get a confirmation that MtGox accepts.
That's correct, and what I said from the beginning: the whole attack can be performed in 2h. 6 blocks in a row that require twice the time are not statistically insignificant. |
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Then the problem is insecure pool design.
I'm sorry. Have I somehow missed what this entire thread is about? Pools reduce the security of bitcoin. End of line. j Of course they do. That's trivial. But you cannot enforce that people don't do pools. So you have to discuss how pools could be more secure. EDIT: Btw. deepbit gets huge at the moment.  |
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Please answer to my posting: Your attack still assumes that you can split the internet. That you can dictate what blockchain each miner can see.
No need to "split the internet". The attacker simply withholds the block, on Tycho's server, that are being solved by the miners. Remember that these miners are not connected to the Bitcoin peer-to-peer network. There is no need to isolate them. But you have to distribute the block in the whole mining pool to generate the next one. No you don't. The pool pre-hashes all the data. The pool miners have no idea what they are working on, nor do they need to generate it themselves. Then the problem is insecure pool design. |
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Another detail is that with the half mining power you only get 3 blocks per hour because of the difficulty.
So you need 2 hours in the first place to get a confirmation that MtGox accepts.
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Please answer to my posting: Your attack still assumes that you can split the internet. That you can dictate what blockchain each miner can see.
No need to "split the internet". The attacker simply withholds the block, on Tycho's server, that are being solved by the miners. Remember that these miners are not connected to the Bitcoin peer-to-peer network. There is no need to isolate them. But you have to distribute the block in the whole mining pool to generate the next one. |
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