No.
The transaction and block are valid. The only potential safeguard is hashing power and that just makes it more difficult but not impossible. However one has to consider the value of the loss. All forms of trade (cash, check, credit cards, gold, barter) involve fraud. It will never be eliminated not in Bitcoin, not anywhere.
However the amount of fraud is what matters. To have the ability to generate any more than a token amount of revenue in attacks requries a huge amount of hashing power and a large transaction.
So yeah if someone wants to perform a finney attack to get something that costs small number of BTC it is likely is impossible to avoid. However the increased gain on their capital expense (hashing hardware) is not significant and that likely will keep most miners honest. Large transaction should require 1+ confirmations.
I don't really seel much value in insurance because small transactions are unlikely to be double-spent and large transactions are likely uninsurable against a Finney attack. It is precisely these large transactions which would be the target of a Finney attack (to justify the capital cost required).
I agree with you, but, theoretically, the miners could see that this was a double spend attempt and mine the next block based not on your block, but on the previous one. This would create a fork and invalidate your chain (unless of course you have 51%). But allowing something like this would probably have lots of other implications... |
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I don't agree. Note that we are talking about conflicting transactions only. Which means that if I see 2 transactions spending the same coins from the same address, I will include the one I saw first. Seems like a pretty good strategy for me. Otherwise you can triple-spend, quadruple-spend, ...., N-spend. You just need to keep issuing transactions with higher fees than the others.
The decision strategy for non conflicting transactions can and should be based on fees.
There is no method of enforcing a miner to include or not include a particular transaction. The network specifically allows a miner to include whatever transactions he wishes to in a block. I think you may be confusing nodes with miners. Nodes will only relay the first transaction and ignore the rest. There is no financial incentive to do otherwise. Why would it matter which transaction a miner includes in the block? If this is a 0-confirm attack then the attacker already has the merchandise. He doesn't care which (if any) transaction ever gets included in any block. Yeah... You're right. My post doesn't make sense  |
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Why? His block would be perfectly valid, he would not be violating any protocol rule. Transaction priority should not and probably cannot be defined by the protocol - each miner is free to make its own policy. We should not expect miners to adopt a policy that rejects a transaction for another that pay less fees, at least not when transaction fees become a substantial part of mining reward.
I don't agree. Note that we are talking about conflicting transactions only. Which means that if I see 2 transactions spending the same coins from the same address, I will include the one I saw first. Seems like a pretty good strategy for me. Otherwise you can triple-spend, quadruple-spend, ...., N-spend. You just need to keep issuing transactions with higher fees than the others.
The decision strategy for non conflicting transactions can and should be based on fees. |
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Attempts of the attack I linked to can not be detected, so you would only notice it once its too late.
BDPIC could require 1 block confirmations for merchants with detected double-spend attempts... Your attack is actually the only potential problem. If BDPIC monitors the network correctly, it is almost impossible to double-spend without a pre-mined block. Which makes me wonder (and this is probably a dumb question) if it isn't possible to detect the attack and reject your pre-mined block once you release it. Could the network do this? |
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You'll succeed in the vast majority of attempts if you just add a higher transaction fee to the double-spend.
Transaction fees have nothing to do with it. The only way you will be able to pull this off is with a Finney attack, like jav described, but you will need a decent amount of computational power. 2% of the network is 100GHash/second. |
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Deal made --- I bought a physical copy of Starcraft 2 and I want to the sell the game key because I already have the game registered in my battle.net account (with another key). This will give you full access to the game. You just need to add the key to your battle.net account and then download the game from here. Note that you will only be able to play on european servers because the game was bought in England. I will send you a photo of the CD key so it will be just like owning the game without having the box  The price is 35€ 30€, which is around 14.6 10 bitcoins at current prices. I have never traded here but I have an ebay account with 100% feedback and a good reputation at Bitcoin SE (if that matters...). Send me a PM if you are interested and we can discuss the details. |
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Eu sei o comando para iniciar, com usr, pw e pool. Mas postei só o que retorna o erro. É erro do Ubuntu 11.10?
O erro não é do Ubuntu. Tu é que tens qualquer coisa mal configurada. Ele dá o erro 'At least one server is required'. De certeza que puseste os argumentos bem? Se escreveres aqui o comando com user/pass escondidos se calhar era mais fácil... PS: o comando é algo deste género: ./poclbm.py server=http://user@youremailaddress.com:yourpoolpassword@pit.deepbit.net:8332 -d 1
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Como é que estás a executar o programa? Tens de dar o nome da pool, porta, username/password, etc.
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So, I haven't read 90% of the posts, but can you please stop arguing about whatever you are arguing and go back to the topic?
Also, 11% is very different from 49%...
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Têm de usar sempre pools de fallback caso a principal vá abaixo. Eu minei durante uns tempos na eclipsemc e nunca tive problemas, mas é uma pool pequena... Actualmente já não mino porque iria perder dinheiro com o hardware que tenho.
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Com um lucro de 17 USD/mes demoraria 3 anos para pagar o equipamento. Nesse tempo é claro que preço do bitcoin e a dificuldade de mineração variará bastante. Assim o tempo de retorno do investimento é muito mais um exercício de adivinha quanto será a dificuldade de mineração e o preço do bitcoin.
Isto é muito importante. Daqui a 3 anos a dificuldade será muito superior por isso se os preços se mantiverem é um investimento que não tem retorno. Se os preços subirem talvez dê dinheiro... Em relação a FPGA vs ASIC, convém ler isto. Actualmente não se podem comprar ASICs para mining porque ainda ninguém as fez. É preciso desenhar o circuito e isso é um investimento que ascende às centenas de milhares de dólares. |
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So does lower difficulty likely mean lower price for BTC? Do they correlate in both directions?
I know price definitely effects difficulty in the long run... but visa versa?
This means that miners will get additional 50/100 coins per hour (comparing to the last couple of weeks). I don't think there is a strong relation between difficulty and price, but the price is defined by a lot of factors and the amount of coins received by the miners is definitely one of them. |
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Difficulty down to 1,203,462. So where are all the new coins? |
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A clear breakout over $4 would confirm the reversal.
So are we still bear or are we experiencing the "weekend effect"? |
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The websocket is down, so they can't connect. You have to do all transactions via the site now.
My bot is still running through the old API. I need to change it to websockets, but I have been lazy lately... |
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Thank you very much. Yes I will do it privately. Tradehill is not known for ripping people off correct? They seem like a good company.
If anyone cares to comment on this, or this has ever happened to
you, please let me know.
It's probably going to be ok. It willl just take a little longer to confirm the transaction because they will have to manually process your request. |
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This is off topic, but I think there is no need for another thread: how long do you take to notify the merchant of the transaction? The waiting time may be important for merchants selling digital content for example.
The merchant has three choices for notification, high speed (immediate notification), medium speed (after 1 block), and low speed (after 6 blocks). Nice. If more exchanges/e-wallets implement green addresses it would be an interesting addition to the service. |
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This is off topic, but I think there is no need for another thread: how long do you take to notify the merchant of the transaction? The waiting time may be important for merchants selling digital content for example.
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It is still possible to send/receive money from/to europe, now without the cheap SEPA possibility it cost more fees - thats all.
you have to use the 'international wire' option at mtgox.
its a IBAN/SWIFT way, usually very fast (1-2 hours total on a businessday for my IBAN/SWIFT withdraws) but banking fees on both sides.
if you want to withdraw big money (>10.000 US$) its quite NO PROBLEM. Fees are together (both sides) about 45 US$.
You also can use intersango or bitmarket. I usually do my business at bitmarket when SEPA transfers are frozen at TradeHill/MtGox (which happens very often). Note that we are mining at 4/5 blocks per hour so (theoretically) there are also less bitcoins coming into the market |
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We don't seem to have a good rally thread going. So I decided to start one.
I have been wanting so say this for a while: is it just me or all the threads in the speculation forum are the same? I mean, the initial posts are usually related to the thread title, but after a couple of pages everybody is talking about market predictions, log charts, trends, etc. When I open the forum I feel that clicking in "9 days - 8 green 1 red is this unprecedented?", "How many of you Bears have ever been a victim of a Short Squeeze?" or "Is the price slowly climbing?" is the same. I will just see random content unrelated to the thread title. |
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