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Topic: Fragmentation attack (Read 2384 times)

empoweoqwj

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Quote from: DeepCryptoanalist3 on December 28, 2013, 10:21:49 AM

Quote from: empoweoqwj on December 28, 2013, 03:19:49 AM

Quote from: DeepCryptoanalist3 on December 28, 2013, 03:05:06 AM

Why would it be? For now only just for fun hacks are possible. Who may be interested to spend money on this attack now? BitCoin is not adopted in any country. There is no wealthy bitcoin hater at this point.

The bitcoin network is worth 10 billion dollars now. There are lots of ways to profit from "hacking" the network, should it be possible. Lots of people hack for free, just to show the vulnerability in what they are hacking.

That is exactly what I say. Lots of people hack for free. What if you need some amount of money to organize attack? Even now you can raise transaction fee to unacceptable value for a day if you have 10,000 BTC. Then if the block default size will be raised you will need another billion USD to spam blockchain to the size when the current network clients won't be able to operate. This will literally switch bitcoin network off.

If you think you have identified dangers in the current network that a very rich dude could exploit to bring down bitcoin, you should really report them to to the bitcoin development team

DeepCryptoanalist3

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Quote from: empoweoqwj on December 28, 2013, 03:19:49 AM

Quote from: DeepCryptoanalist3 on December 28, 2013, 03:05:06 AM

bitpop

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That would be awesome. Output will be 0 after transaction fees.

QuestionAuthority

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You lead and I'll watch you walk away.

I think these threads might prove to be entertaining reading for you OP:

https://bitcointalksearch.org/topic/do-you-think-satoshidice-is-blockchain-spam-drop-their-txs-solution-inside-150405

https://bitcointalk.org/index.php?topic=86679.20

empoweoqwj

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Quote from: DeepCryptoanalist3 on December 28, 2013, 03:05:06 AM

Quote from: empoweoqwj on December 27, 2013, 10:16:56 PM

I think any attack on the bitcoin network that works would have happened by now. How many have their been?

DeepCryptoanalist3

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Quote from: empoweoqwj on December 27, 2013, 10:16:56 PM

I think any attack on the bitcoin network that works would have happened by now. How many have their been?

empoweoqwj

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Quote from: DeepCryptoanalist3 on December 27, 2013, 02:09:53 AM

Quote from: Meizirkki on December 27, 2013, 02:06:07 AM

Afaik the block would still get rejected, if it surpasses the hard limit of 1Mb

Yes this limit ruined all my evil plans Angry

I think any attack on the bitcoin network that works would have happened by now. How many have their been?

Meizirkki

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Quote from: DeepCryptoanalist3 on December 27, 2013, 02:09:53 AM

Quote from: Meizirkki on December 27, 2013, 02:06:07 AM

Afaik the block would still get rejected, if it surpasses the hard limit of 1Mb

Yes this limit ruined all my evil plans Angry

Were you going to set up an evil pool? Cheesy

DeepCryptoanalist3

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Quote from: Meizirkki on December 27, 2013, 02:06:07 AM

Afaik the block would still get rejected, if it surpasses the hard limit of 1Mb

Yes this limit ruined all my evil plans Angry

Meizirkki

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Afaik the block would still get rejected, if it surpasses the hard limit of 1Mb

Meizirkki

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Quote from: DeepCryptoanalist3 on December 27, 2013, 01:59:45 AM

Quote from: Meizirkki on December 27, 2013, 01:50:47 AM

As DeathAndTaxes said it would take a small fortune for anyone to successfully include a gigantic transaction into a block. If you tried to send 1Gb transaction without any fee it'd get rejected by every standard node in the network.

We already discussed this and now are discussing scenario in which you are an admin of a mining pool and you can just add some spam data to the block you are forming. This spam data shouldn't prevent others from using your block as a previous in a chain. Its just a business. If your block is ending the longest chain others will adopt it no matter how big it is.

ah, got it

DeepCryptoanalist3

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Quote from: Meizirkki on December 27, 2013, 01:50:47 AM

Meizirkki

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DeepCryptoanalist3

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Quote from: DeathAndTaxes on December 27, 2013, 01:22:57 AM

Quote from: DeepCryptoanalist3 on December 27, 2013, 01:15:45 AM

Fee to miners I mean... fraction of a mined coins which pool grabs. It doesn't matter anyway in context of attack.

Of course it matters in the context of an attack. It will cost you at least 0.08192 per MB added to the blockchain in fees to miners excluding any value sent to outputs.

Why it will cost me something if I add spam data to the block? If there is no transaction with good enough fee in the network. But it looks like I miss something. Propagation time. Reading next...

Quote from: DeathAndTaxes on December 27, 2013, 01:22:57 AM

Larger blocks take longer to relay and confirm. Orphan rates depends on relative differences in block size.

I thought that at least biggest miners have a rather good internet connection and will download this huge block in a minute or two. Also the size of a block shouldn't be a problem for such a long lived peer nodes in a network. It is a big surprise to me that the size of a block related to the speed of its adoption as a previous block by other big miners.

DeathAndTaxes

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Gerald Davis

Quote from: DeepCryptoanalist3 on December 27, 2013, 01:15:45 AM

Quote from: DeathAndTaxes on December 27, 2013, 01:06:03 AM

Eligius is not free from any fee.

Fee to miners I mean... fraction of a mined coins which pool grabs. It doesn't matter anyway in context of attack.

Of course it matters in the context of an attack. It will cost you at least 0.08192 per MB added to the blockchain in fees to miners excluding any value sent to outputs.

Quote from: DeathAndTaxes on December 27, 2013, 01:06:03 AM

If Eligius made massive, spammy blocks which took excessively long time to confirm the miners would simply leave.

Why It will took excessively long time to confirm if massive blocks were standard?

Larger blocks take longer to relay and confirm. Orphan rates depends on relative differences in block size. If the average block is 10 GB then making a 1 GB spam block is just pissing in the wind. It would be like trying to take down the internet by emailing everyone you know.

Spam is only an attack if it is large relative to genuine traffic. If Eligius was making 1 GB blocks and the other miners were making 0.5 MB blocks Elgius would have a much higher propagation time and thus would lose a much higher % of revenue to orphans. Net revenue (after orphan losses) would plummet, miners would leave in droves (if only to protect their own bottom line) and the power of the attack would be greatly reduced.

DeepCryptoanalist3

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Quote from: DeathAndTaxes on December 27, 2013, 01:06:03 AM

Eligius is not free from any fee.

Fee to miners I mean... fraction of a mined coins which pool grabs. It doesn't matter anyway in context of attack.

Quote from: DeathAndTaxes on December 27, 2013, 01:06:03 AM

If Eligius made massive, spammy blocks which took excessively long time to confirm the miners would simply leave.

Why It will took excessively long time to confirm if massive blocks were standard?

DeathAndTaxes

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Gerald Davis

Eligius is not free from any fee.

Quote

Will include transactions in its blocks if the sender pays a fee of at least 0.1 TBC (0.00004096 BTC) per 512 bytes.

http://eligius.st/~gateway/faq-page

Of course like I said using a public pool would be short lived. If Eligius made massive, spammy blocks which took excessively long time to confirm the miners would simply leave. Some would leave because they woudl view it as an attack on Bitcoin, others would leave simply because orphaned blocks are in effect lost revenue. Why mine at Eligius (in this hypothetical scenario) and lose 5% of gross revenue when you could mine just about anywhere else and lose less?

DeepCryptoanalist3

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Quote from: DeathAndTaxes on December 27, 2013, 12:44:01 AM

No it won't be denied. It isn't illegal, just non-standard. However the block limit still applies and larger blocks (but smaller than 1MB or current limit) are more likely to be orphaned. Of course running a massive hashing farm with a significant fraction of the network is a non-trivial cost as well. If you are a public pool, your attack is very public so I would imagine miners simply leave for other pools very quickly. If you are looking to build a private multi-PH pool plus continually upgrading to keep up with network growth I hope you have tens of millions of USD handy.

Then again average block is currently 250KB so you could add maybe 750KB to the blockchain per solved block. With 10% of the network it would only take you 100 or so days assuming 0% orphan rate.

ELIGIUS is free from any fee. Ok then the final frontier is the current block size limit. If there were possible to form a block larger than 1MB say 100MB it will be possible to eligius to populate blockchain with a few spam gigs through the day, fragmenting only a few btc.

DeathAndTaxes

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Gerald Davis

Quote from: DeepCryptoanalist3 on December 27, 2013, 12:37:29 AM

But it could be compressed in that case. It couldn't if addresses are different.

Not in any meaningful way.

Quote from: DeathAndTaxes on December 27, 2013, 12:28:03 AM

Still even before IsDust this attack wouldn't work. Low priority tx are not relayed unless they pay a fee and that fee would cost you 0.1 mBTC per KB. So sure you can add 1 GB to the blockchain, no problem. It just will cost you 100 BTC minimum in fees per GB plus the cost of the value of the tx themselves.

What if you are a big miner, a pool owner for example, and you can produce such block with such transaction by you own will? This block will be declined by others only because of IsDust function.
[/quote]

No it won't be denied. It isn't illegal, just non-standard. However the block limit still applies and larger blocks (but smaller than 1MB or current limit) are more likely to be orphaned. Of course running a massive hashing farm with a significant fraction of the network is a non-trivial cost as well. If you are a public pool, your attack is very public so I would imagine miners simply leave for other pools very quickly. If you are looking to build a private multi-PH pool plus continually upgrading to keep up with network growth I hope you have tens of millions of USD handy.

Then again average block is currently 250KB so you could add maybe 750KB to the blockchain per solved block. With 10% of the network it would only take you 100 or so days assuming 0% orphan rate.

DeepCryptoanalist3

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Quote from: DeathAndTaxes on December 27, 2013, 12:28:03 AM

Quote from: DeepCryptoanalist3 on December 27, 2013, 12:05:08 AM

The idea was to send 100 million outputs per BTC to different addresses of course.

Which is no different than sending 100 million outputs to the same address. The number of unique addresses is irrelivent.

But it could be compressed in that case. It couldn't if addresses are different.

Quote from: DeathAndTaxes on December 27, 2013, 12:28:03 AM

What if you are a big miner, a pool owner for example, in this case you aren't depend from relay and you can produce such block with such transaction by your own will? This block will be declined by others only because of IsDust function.