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Topic: nothing to see here, move along. (Read 9427 times)

legendary
Activity: 1764
Merit: 1002
July 16, 2015, 11:50:13 AM
#48
So a block size limit increase would fix the problem because for this to be profitable, the attacker needs to have at least half of the block be legitimate transactions and that there still be a backlog of transactions, yes? And since there isn't that much real transaction volume, raising the limit to the suggested compromise of 8 Mb would solve this issue for now since it suddenly becomes unprofitable to continue to attack until transaction volume increases.

Good post, totally get the math... all in on the theory...

Looking at the actuals, I'm not convinced that this is actively happening, though I see how you theorize it could.

Checking block shares, and the biggest fish only holds 20%

source: https://chain.so/btc

Though I will concead that it may be possible that the smaller pools are actually the larger holders running "shadow miners" that appear to be anon, but are really wholly owned subsidiaries of the bigger players.

Another problem I see is that blocks are not full by any stretch.  Miners (for reasons that are their own) are leaving many blocks 2/3 empty.

source: https://tradeblock.com/blockchain/

So any miner that had less than 38% the share could simply start filling blocks to the brim.  Perhaps I'm on a tangent here, but I've never understood why miners running rooms full of ASICs don't devote a few high power CPUs (useless for mining) to doing block stuffing.  It seems like getblocktemplate and hashing would be non-intersecting.  So pooring $$ into CPU could be independent to pooring money into hashing.

I still have questions tho, like how high can they push transaction fees and dose this mean the end of micro transactions in the long term?

If I followed, the condition they are driving is not the fee price, but rather the spam ratio.  As long as they can continue to mine some percentage X of their own spam then they make a profit even if fees go to 1 satoshi.  The "canaibalism" ration X would float depending on two factors... what their current share of hash rate is, and how much normal traffic there is.

but this graph from Tradeblock shows that more recent avg block sizes are just over 700kB:



yeah, the table you put up is wrong.  it shows the max block size to be 776kB which is clearly wrong.  we've had a consistent stream of 950kB+ come thru over the last few weeks. 
legendary
Activity: 1764
Merit: 1002
July 16, 2015, 11:31:17 AM
#47
So a block size limit increase would fix the problem because for this to be profitable, the attacker needs to have at least half of the block be legitimate transactions and that there still be a backlog of transactions, yes? And since there isn't that much real transaction volume, raising the limit to the suggested compromise of 8 Mb would solve this issue for now since it suddenly becomes unprofitable to continue to attack until transaction volume increases.

Good post, totally get the math... all in on the theory...

Looking at the actuals, I'm not convinced that this is actively happening, though I see how you theorize it could.

Checking block shares, and the biggest fish only holds 20%

source: https://chain.so/btc

Though I will concead that it may be possible that the smaller pools are actually the larger holders running "shadow miners" that appear to be anon, but are really wholly owned subsidiaries of the bigger players.

Another problem I see is that blocks are not full by any stretch.  Miners (for reasons that are their own) are leaving many blocks 2/3 empty.

source: https://tradeblock.com/blockchain/

So any miner that had less than 38% the share could simply start filling blocks to the brim.  Perhaps I'm on a tangent here, but I've never understood why miners running rooms full of ASICs don't devote a few high power CPUs (useless for mining) to doing block stuffing.  It seems like getblocktemplate and hashing would be non-intersecting.  So pooring $$ into CPU could be independent to pooring money into hashing.

I still have questions tho, like how high can they push transaction fees and dose this mean the end of micro transactions in the long term?

If I followed, the condition they are driving is not the fee price, but rather the spam ratio.  As long as they can continue to mine some percentage X of their own spam then they make a profit even if fees go to 1 satoshi.  The "canaibalism" ration X would float depending on two factors... what their current share of hash rate is, and how much normal traffic there is.

but this graph from Tradeblock shows that more recent avg block sizes are just over 700kB:

hero member
Activity: 714
Merit: 500
July 16, 2015, 10:24:43 AM
#46
I'm assuming since the original post and thread title has been edited, it turns out this wasn't the case?  Even if the initial conclusions may have been a little premature in this particular instance, it's still reassuring to know that people spend time considering all the possibilities and doing their best to make sure this system continues to function as intended.  I applaud the OP's enthusiasm, but just suggest tempering it a touch and having others check the figures before announcing your findings.  Don't let this prevent you from asking bold questions in future, though, it could well pay off next time.
The only premature thing, was to delete his first post.
There is nothing wrong with posting a theory. The whole point about posting a theory is so people can look into it and tell if the author has made some errors.
Nothing to be ashamed of.
legendary
Activity: 3948
Merit: 3191
Leave no FUD unchallenged
July 16, 2015, 10:20:49 AM
#45
I'm assuming since the original post and thread title has been edited, it turns out this wasn't the case?  Even if the initial conclusions may have been a little premature in this particular instance, it's still reassuring to know that people spend time considering all the possibilities and doing their best to make sure this system continues to function as intended.  I applaud the OP's enthusiasm, but just suggest tempering it a touch and having others check the figures before announcing your findings.  Don't let this prevent you from asking bold questions in future, though, it could well pay off next time.
legendary
Activity: 1386
Merit: 1053
Please do not PM me loan requests!
July 16, 2015, 10:07:36 AM
#44
Lets imagine your mine with half hashpower. Lets imagine that a block can contain 6000 transactions.  Attacker has 1/2 hashpower.  Offered load is 4000 tx/block.

Attacker crafts 2000/tx block at 1coin/tx fee level. Making the rest match him (plus episilon, which we'll disregard).

His average cost for spam is 1000 coin/block (2000 * 1-rate).
His average income is 2000 coin/block (4000 * rate).  (He doesn't get income from his spam, he saves its cost however; see prior line)
His net income is 1000 coins/block, on average.
Well, what if the attacker's block is orphaned, and other pools pick up the now-unconfirmed transactions with 1 BTC fees? Would the attacker be able to prevent that?
legendary
Activity: 1988
Merit: 1012
Beyond Imagination
July 16, 2015, 09:48:38 AM
#43

Lets imagine your mine with half hashpower. Lets imagine that a block can contain 6000 transactions.  Attacker has 1/2 hashpower.  Offered load is 4000 tx/block.

Attacker crafts 2000/tx block at 1coin/tx fee level. Making the rest match him (plus episilon, which we'll disregard).

His average cost for spam is 1000 coin/block (2000 * 1-rate).
His average income is 2000 coin/block (4000 * rate).  (He doesn't get income from his spam, he saves its cost however; see prior line)
His net income is 1000 coins/block, on average.


Is that possible? Wink

His average cost for spam is 1000 coin/block, but his average income is not 2000 coin/block. Because even there are 2000 transactions with a fee of 1 BTC stay at the top of the queue and get transacted immediately, the rest 4000 transactions might still pay a fee of  0.01 bitcoin, they were just pushed back in the queue, not obliged to follow the highest paying fee. The fee would only rise to 1 coin/tx if all those transactions are willing to pay for that. In a word, the spammer can only raise the fee to the amount of money he spent, the rest is not up to him

And of course he could spend huge and spam all the 6000 transactions with 1 coin/tx to occupy all the block space, then as you said that will only benefit the non-spamming miners, and those miners would still include the transactions that they want to broadcast in their blocks with a minimum fee (like exchange-mining farm cooperation)
legendary
Activity: 1988
Merit: 1012
Beyond Imagination
July 16, 2015, 09:24:29 AM
#42
Suppose that there are 10 blocks, each with a fee of 2 btc (in future). Now a large mining pool commanding 50% of hash power decided to spam the network and raise the fee for each block to 3 btc. So he spend 1 bitcoin at each block as fee for his spamming transactions, that's 10 bitcoins total, and he mined 5 of them back, his net loss is 5 bitcoins, how would he become profitable?

legendary
Activity: 1386
Merit: 1009
July 16, 2015, 08:39:51 AM
#41
   In a future bitcoin economy where most of the revenue is from tx fees this won't be an issue either, unless the blocksize is kept the same. I like this post though, becuase it creates a good case against fee contention (which is created by limited blocksize). Increasing the blocksize/removing the cap entirely solves this problem (and many others) permanently.
It also creates/worsens other problems. This has been discussed on the dev mailing list countless times.

Moreover, by dropping the cap you don't really kill the fee market, just change it. Including additional transactions in a block has its cost, e.g. increased orphaning probability.

I am personally in favor of some flexible cap that is adjusted based on actual transaction volume.
legendary
Activity: 1137
Merit: 1001
July 16, 2015, 08:27:03 AM
#40
A pool with 30% of mining power may have an incentive to do this. But increasing fees means the pool with a 10% share increases its revenue without doing any work. So, in an ironic twist, this should prevent a monopoly forming? Its better to be the 2nd biggest mining operation, and let #1 push up the fees.

but there are no pool with more than 17-18% for now, so how can they do this attack? are the pool working together to do this and then split the profit?

if this is the case, this is really a miners's monopoly, chinese miners working together to screw bitcoin is an understimated issue, they can also perform a 51% if there will be a real reason to do it

higher fees means more miners. These new miners do not want to be part of the "monopoly", but do want monopoly prices.
hero member
Activity: 639
Merit: 500
July 16, 2015, 08:20:45 AM
#39
A pool with 30% of mining power may have an incentive to do this. But increasing fees means the pool with a 10% share increases its revenue without doing any work. So, in an ironic twist, this should prevent a monopoly forming? Its better to be the 2nd biggest mining operation, and let #1 push up the fees.

but there are no pool with more than 17-18% for now, so how can they do this attack? are the pool working together to do this and then split the profit?

if this is the case, this is really a miners's monopoly, chinese miners working together to screw bitcoin is an understimated issue, they can also perform a 51% if there will be a real reason to do it
legendary
Activity: 1137
Merit: 1001
July 16, 2015, 08:14:49 AM
#38
A pool with 30% of mining power may have an incentive to do this. But increasing fees means the pool with a 10% share increases its revenue without doing any work. So, in an ironic twist, this should prevent a monopoly forming? Its better to be the 2nd biggest mining operation, and let #1 push up the fees.
legendary
Activity: 1596
Merit: 1027
July 16, 2015, 06:44:44 AM
#37
Is this really going on right now!? and if it can happen it means that the protocol is broken.
Now that you find out this anomaly what are your options to solve it?
legendary
Activity: 2674
Merit: 1083
Legendary Escrow Service - Tip Jar in Profile
July 16, 2015, 05:45:05 AM
#36
I would like to add that at this point i would prefer that transactions have to pay fees depending on the amount of outputs, similar like litecoin prevents spam attacks. I think there is no reason not to handle it that way. A transaction with more than 2 outputs are simply more than one transactions. If you send 100 letters by mail then you dont pay a fee once only because you bring all the letters to the post office in a big box. You still have to pay for all letters. You might be able to save some percent but its very different.

So why should transaction be handled so differently? We could solve the whole thing quick i guess.
legendary
Activity: 2674
Merit: 1083
Legendary Escrow Service - Tip Jar in Profile
July 16, 2015, 05:16:45 AM
#35
I think its not needed to look at if any player has the needed amount of hashpower, we know that miningcorporations in china hold the majority of the hashingpower (i believe i read something >60%) and there is no one stopping them from building a monopoly in secret. Means they will still mine alone but they put money together to spam the network. The costs would be low enough for them to force the fees up and still earn. And since chinese miners most probably have the advantage of cheapest power cost and cheapest way to create miners, the profit the rest of the miners has from this rise in fees would not be so high anymore.

This of course only works when the blocks are nearly filled already, so with 8MB blocks it would not work first but at one point it would work again i guess.

What i fear is this kind of ruling over bitcoin. I mean Satoshi wanted to be free from banks and their rules and now its possible to enforce fees, like a bank would do. Dont like that.

The price of bitcoin didnt drop because of the spam attack, in fact it went up considerably. So i think the spam attack had no real effect on the bitcoin price.

I sometimes read we would simply need to raise the fees so that miners get paid "fairly". This is not possible. Block halving will happen and there is no way fees will back that. If miners could enforce this then bitcoin would be dead by fees.

So there is no way that miners can proceed the way they do. They will earn less. This is nothing new, mining hardware was old all the time and replaced. So a fair payment only will come from adoption. Spamming the network effectively hinders adoption. One can see this easily in numerous posts on the net. And newbies coming to bitcoin, seeing that bitcoin doesnt work, is bad for sure.
-ck
legendary
Activity: 4088
Merit: 1631
Ruu \o/
July 16, 2015, 04:50:19 AM
#34
Even if the math does work out (which I'm having trouble believing), in all honesty I think you're grossly overestimating the capabilities of the two pools that could possibly be doing this...  and their own block size handling is working against such an "attack" with regular (transaction) empty block solves Roll Eyes
legendary
Activity: 2674
Merit: 3000
Terminated.
July 16, 2015, 03:23:14 AM
#33
This is quite a interesting story. I wonder how this is going to work for them once we have bigger blocks, or sidechains or lightning network, etc.?
Everything is prone to abuse in some way until someone does something about it. It is actually quite possible that someone is being very malicious about this. However, more proof is required as you're just making an assumption that someone is doing it because it is most likely profitable for them.
legendary
Activity: 1302
Merit: 1008
Core dev leaves me neg feedback #abuse #political
July 16, 2015, 03:19:07 AM
#32
sorry if I'm a bit slow but I don't get it.

if a 38% miner spends fees that he gets back, how does that help him?
and how does it hurt other miners ? if anything it would seem that the other
miners would pick up extra fees, making them more competitive, not less.

someone please explain this.

You have answered your own confusion with the bolded part. The one that would pick up "more" miners fee will be the one that owns more hashing power. The miners fee will be increasing because people will want their transaction to get confirmed faster if there is someone spamming the network thus this means that if the spammer is a person behind who owns atleast 38 % of the hashing power then this person will get profit with the increasing fee ( this would be somewhat a miners fee cartel )

Let's work the math.  If 2/3 of the transactions actually processed are "real", then whoever is maintaining the backlog is paying the tx fees for 1/3 of every block. If this is someone with half the mining power then they get half of their third back, so their average cost per block is the fees for 1/6 of the block.  If we are talking about someone with half the mining power, their average return per block is 1/2 the fees for a block.  Because 1/2 is greater than 1/3, they are making a profit.  

-snip-

 It is not in their best interests to add bogus transactions to the queue because with a smaller fraction than 38% of the mining power they would lose money on the fees they invest.

-snip-

Miners for whom this is profitable must control at least 38% of the mining power.  Therefore there can be no more than two miners doing it at a profit.  

That makes NO sense.
 
If a block of fees is, say $100...

You could argue that they make
a "profit" of $50-$33 = $17 but
the other half of the network
makes $50-0 =$50.

The rest of the network is earning
MORE per hashrate.  I think others
d4n13, gmaxwell have more precisely
detailed it mathematically.
full member
Activity: 210
Merit: 104
“Create Your Decentralized Life”
July 16, 2015, 03:10:23 AM
#31
Good post, totally get the math... all in on the theory...

Thinking it over a bit (beer++)

Let's work the math.  If 2/3 of the transactions actually processed are "real", then whoever is maintaining the backlog is paying the tx fees for 1/3 of every block. If this is someone with half the mining power then they get half of their third back, so their average cost per block is the fees for 1/6 of the block.  If we are talking about someone with half the mining power, their average return per block is 1/2 the fees for a block.  Because 1/2 is greater than 1/3, they are making a profit.  

I think I found your bug....

You fail to account for the revenue of the other pools.  You state the profit per block won but not the loss per block lost.

Proof:


In the end the spammer (Bob) ends up making more money for the honest miner (Alice).

It's a zero sum game.  Bob is the only one dumping extra money into a system that both Bob and Alice draw from.

 
legendary
Activity: 2562
Merit: 1414
July 16, 2015, 03:05:13 AM
#30
sorry if I'm a bit slow but I don't get it.

if a 38% miner spends fees that he gets back, how does that help him?
and how does it hurt other miners ? if anything it would seem that the other
miners would pick up extra fees, making them more competitive, not less.

someone please explain this.

You have answered your own confusion with the bolded part. The one that would pick up "more" miners fee will be the one that owns more hashing power. The miners fee will be increasing because people will want their transaction to get confirmed faster if there is someone spamming the network thus this means that if the spammer is a person behind who owns atleast 38 % of the hashing power then this person will get profit with the increasing fee ( this would be somewhat a miners fee cartel )

Let's work the math.  If 2/3 of the transactions actually processed are "real", then whoever is maintaining the backlog is paying the tx fees for 1/3 of every block. If this is someone with half the mining power then they get half of their third back, so their average cost per block is the fees for 1/6 of the block.  If we are talking about someone with half the mining power, their average return per block is 1/2 the fees for a block.  Because 1/2 is greater than 1/3, they are making a profit.  

-snip-

 It is not in their best interests to add bogus transactions to the queue because with a smaller fraction than 38% of the mining power they would lose money on the fees they invest.

-snip-

Miners for whom this is profitable must control at least 38% of the mining power.  Therefore there can be no more than two miners doing it at a profit.  
legendary
Activity: 3248
Merit: 1070
July 16, 2015, 02:59:35 AM
#29
is this spamming attack so profitable that they will keep it indefinitely?

how much they are actually doing in comparison to their normal mining activity

it can't be that big, they(we are assuming that chinese are doing this, because of high % of the network in their hand) are already controlling the majority of the minign activity, do they really need more tiny profit?
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