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NewbieActivity: 55Merit: 0 Guild pool a 51% threat? March 22, 2013, 12:36:24 PM #1



http://blockchain.info/pools



http://www.btcguild.com/index.php?page=pool_stats



The guild pool speed has increased +400% in the last 6 weeks.





I dont know how guild pool operates so i ask you:



Is there a possible threat for a 51% attack?





Lets make some calculations:





Gmax = Gn + (k x h)



X = Xn + (k x h)





Gmax : guild pool speed for becoming a 51% threat. (Gh/s)



Gn: guild pool speed now (Gh/s)



X: total network hash rate if Gmax is reached (Gh/s)



Xn: total network hash rate now (Gh/s)



k: number of ASICs



h: ASIC hash rate (Gh/s)





Assume that the network's computation speed (do not include guild pool speed in the networks total hash rate) does not grow so fast as the guild pool speed does.

A good assumption because the networks computation speed has grown +100% in the last 6 weeks Vs a +400% increase in guild pool speed.



http://bitcoin.sipa.be/speed-lin.png



Also the +100% increase includes the +400% guild pool increase. So the increase of the network's computation speed without including the guild pool increase is less than 100%.

Guild pool has added 16000Gh/s to the network the last 6 weeks. The rest network has added 10000Gh/s to the whole network the last 6 weeks.

So the rest network computation speed has a +40% increase Vs a +400% increase of guild pool speed.



How many ASICs should be added in the guild pool in order to become a threat?



Gmax / X > 0.51 =>



[ Gn + (k x h) ] / [ Xn + (k x h) ] > 0.51 =>



.

.

.



k > [ Gn-0.51Xn ] / [ 0.51h-h ]



Gn = 20000Gh/s



Xn=50000Gh/s



h=60Gh/s

.

.

.

k>187







So 187 ASICs (60Gh/s each) or 11000gh/s must be added to guild pool in order to become a 51% threat assuming that the rest network grows very slowly.



This means that guild pool will reach the threatening point in 3-4 weeks if the situation does not change. BTC guild pool has the 40% of the total network power.The guild pool speed has increased +400% in the last 6 weeks.I dont know how guild pool operates so i ask you:Is there a possible threat for a 51% attack?Lets make some calculations:Gmax = Gn + (k x h)X = Xn + (k x h)Gmax : guild pool speed for becoming a 51% threat. (Gh/s)Gn: guild pool speed now (Gh/s)X: total network hash rate if Gmax is reached (Gh/s)Xn: total network hash rate now (Gh/s)k: number of ASICsh: ASIC hash rate (Gh/s)Assume that the network's computation speed (do not include guild pool speed in the networks total hash rate) does not grow so fast as the guild pool speed does.A good assumption because the networks computation speed has grown +100% in the last 6 weeks Vs a +400% increase in guild pool speed.Also the +100% increase includes the +400% guild pool increase. So the increase of the network's computation speed without including the guild pool increase is less than 100%.Guild pool has added 16000Gh/s to the network the last 6 weeks. The rest network has added 10000Gh/s to the whole network the last 6 weeks.So the rest network computation speed has a +40% increase Vs a +400% increase of guild pool speed.How many ASICs should be added in the guild pool in order to become a threat?Gmax / X > 0.51 =>[ Gn + (k x h) ] / [ Xn + (k x h) ] > 0.51 =>k > [ Gn-0.51Xn ] / [ 0.51h-h ]Gn = 20000Gh/sXn=50000Gh/sh=60Gh/sk>187So 187 ASICs (60Gh/s each) or 11000gh/s must be added to guild pool in order to become a 51% threat assuming that the rest network grows very slowly.This means that guild pool will reach the threatening point in 3-4 weeks if the situation does not change.

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VIPLegendaryActivity: 980Merit: 1000 Re: Guild pool a 51% threat? March 22, 2013, 02:35:52 PM #2 I do regularly chat with the Operator of BTCGuild, he is concerned at the rapid growth too, if you look in his thread he even mentions it



despite many peoples worst thoughts the vast majority of pooloperators are here to provide good quality mining experience to miners, verify Bitcoin transactions and support Bitcoin, not to destroy it...





Ozcoin Pooled Mining Pty Ltd https://ozcoin.net Double Geometric Reward System https://lc.ozcoin.net for Litecoin mining DGM| https://crowncloud.net VPS and Dedicated Servers for the BTC community

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LegendaryActivity: 1750Merit: 1007 Re: Guild pool a 51% threat? March 22, 2013, 02:57:31 PM #3 Quote from: Graet on March 22, 2013, 02:35:52 PM I do regularly chat with the Operator of BTCGuild, he is concerned at the rapid growth too, if you look in his thread he even mentions it



despite many peoples worst thoughts the vast majority of pooloperators are here to provide good quality mining experience to miners, verify Bitcoin transactions and support Bitcoin, not to destroy it...







I have been increasingly active, especially in threads that are voicing concerns. While it makes no economic sense to perform a 51% attack (it would kill confidence, thus tank the value of Bitcoin), it is always a concern just because the possibility it could happen is enough to cause some of that panic.



Right now, BTC Guild is a little under 40% in the last 24 hours, and had decent luck in these last 24 hours which slight boost to that percentage (assuming overall network luck was neutral). If we see consistent upward percentage movement and reach a higher level, I will be killing the getwork side of the pool with very short notice in order to prevent 51% from happening.



I'm hopeful that the shipment of Avalons outside of China will level out the pool speeds more, and that ASICMINER's next round of speed will be added to Ozcoin or another pool, rather than stacking more onto BTC Guild. These two factors should put the pool speeds into a more balanced state. I have been increasingly active, especially in threads that are voicing concerns. While it makes no economic sense to perform a 51% attack (it would kill confidence, thus tank the value of Bitcoin), it is always a concern just because the possibility it could happen is enough to cause some of that panic.Right now, BTC Guild is a little under 40% in the last 24 hours, and had decent luck in these last 24 hours which slight boost to that percentage (assuming overall network luck was neutral). If we see consistent upward percentage movement and reach a higher level, I will be killing the getwork side of the pool with very short notice in order to prevent 51% from happening.I'm hopeful that the shipment of Avalons outside of China will level out the pool speeds more, and that ASICMINER's next round of speed will be added to Ozcoin or another pool, rather than stacking more onto BTC Guild. These two factors should put the pool speeds into a more balanced state. RIP BTC Guild, April 2011 - June 2015

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Sr. MemberActivity: 406Merit: 250LTC Re: Guild pool a 51% threat? March 22, 2013, 03:03:02 PM #4 If one pool operator wants to go evil, he may just drop PPS fee to 0, then he will get +51% in a short time (new asic units concentrate alot of mobile hashpower in few user hands).

So, in the end, the question is how much we trust pool operators.

https://bitcointalk.org/index.php?topic=310926

Litecoin FPGA shop -> 25Khs at 5W Litecoin USB dongle (FPGA), 45kHs overclockedLitecoin FPGA shop -> http://ltcgear.com

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LegendaryActivity: 1428Merit: 1000Okey Dokey Lokey Re: Guild pool a 51% threat? March 24, 2013, 07:34:19 PM #7 Quote from: eleuthria on March 22, 2013, 02:57:31 PM Quote from: Graet on March 22, 2013, 02:35:52 PM I do regularly chat with the Operator of BTCGuild, he is concerned at the rapid growth too, if you look in his thread he even mentions it



despite many peoples worst thoughts the vast majority of pooloperators are here to provide good quality mining experience to miners, verify Bitcoin transactions and support Bitcoin, not to destroy it...







I have been increasingly active, especially in threads that are voicing concerns. While it makes no economic sense to perform a 51% attack (it would kill confidence, thus tank the value of Bitcoin), it is always a concern just because the possibility it could happen is enough to cause some of that panic.



Right now, BTC Guild is a little under 40% in the last 24 hours, and had decent luck in these last 24 hours which slight boost to that percentage (assuming overall network luck was neutral). If we see consistent upward percentage movement and reach a higher level, I will be killing the getwork side of the pool with very short notic e in order to prevent 51% from happening.



I'm hopeful that the shipment of Avalons outside of China will level out the pool speeds more, and that ASICMINER's next round of speed will be added to Ozcoin or another pool, rather than stacking more onto BTC Guild. These two factors should put the pool speeds into a more balanced state.

I have been increasingly active, especially in threads that are voicing concerns. While it makes no economic sense to perform a 51% attack (it would kill confidence, thus tank the value of Bitcoin), it is always a concern just because the possibility it could happen is enough to cause some of that panic.Right now, BTC Guild is a little under 40% in the last 24 hours, and had decent luck in these last 24 hours which slight boost to that percentage (assuming overall network luck was neutral). If we see consistent upward percentage movement and reach a higher level,e in order to prevent 51% from happening.I'm hopeful that the shipment of Avalons outside of China will level out the pool speeds more, and that ASICMINER's next round of speed will be added to Ozcoin or another pool, rather than stacking more onto BTC Guild. These two factors should put the pool speeds into a more balanced state. What exactly would that do? Boot off all GPU miners? Im still aimed at 8332

GAWminers and associated things are not to be trusted, Especially the "mineral" exchange http://bitcoin-otc.com/viewratingdetail.php?nick=DingoRabiit&sign=ANY&type=RECV https://bitcointalk.org/index.php?topic=857670.0 GAWminers and associated things are not to be trusted, Especially the "mineral" exchange

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LegendaryActivity: 1750Merit: 1007 Re: Guild pool a 51% threat? March 24, 2013, 07:42:12 PM #8 Quote from: JackRabiit on March 24, 2013, 07:34:19 PM Quote from: eleuthria on March 22, 2013, 02:57:31 PM Quote from: Graet on March 22, 2013, 02:35:52 PM I do regularly chat with the Operator of BTCGuild, he is concerned at the rapid growth too, if you look in his thread he even mentions it



despite many peoples worst thoughts the vast majority of pooloperators are here to provide good quality mining experience to miners, verify Bitcoin transactions and support Bitcoin, not to destroy it...







I have been increasingly active, especially in threads that are voicing concerns. While it makes no economic sense to perform a 51% attack (it would kill confidence, thus tank the value of Bitcoin), it is always a concern just because the possibility it could happen is enough to cause some of that panic.



Right now, BTC Guild is a little under 40% in the last 24 hours, and had decent luck in these last 24 hours which slight boost to that percentage (assuming overall network luck was neutral). If we see consistent upward percentage movement and reach a higher level, I will be killing the getwork side of the pool with very short notic e in order to prevent 51% from happening.



I'm hopeful that the shipment of Avalons outside of China will level out the pool speeds more, and that ASICMINER's next round of speed will be added to Ozcoin or another pool, rather than stacking more onto BTC Guild. These two factors should put the pool speeds into a more balanced state.

I have been increasingly active, especially in threads that are voicing concerns. While it makes no economic sense to perform a 51% attack (it would kill confidence, thus tank the value of Bitcoin), it is always a concern just because the possibility it could happen is enough to cause some of that panic.Right now, BTC Guild is a little under 40% in the last 24 hours, and had decent luck in these last 24 hours which slight boost to that percentage (assuming overall network luck was neutral). If we see consistent upward percentage movement and reach a higher level,e in order to prevent 51% from happening.I'm hopeful that the shipment of Avalons outside of China will level out the pool speeds more, and that ASICMINER's next round of speed will be added to Ozcoin or another pool, rather than stacking more onto BTC Guild. These two factors should put the pool speeds into a more balanced state.

What exactly would that do? Boot off all GPU miners? Im still aimed at 8332

It would remove ~15% of the pool's hash power, including the part of the pool that contains the most undetected botnets, which is yet another plus for getting rid of getwork. However, I don't think it will be needed. BTC Guild is still under 40% at this time. It would remove ~15% of the pool's hash power, including the part of the pool that contains the most undetected botnets, which is yet another plus for getting rid of getwork. However, I don't think it will be needed. BTC Guild is still under 40% at this time. RIP BTC Guild, April 2011 - June 2015

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LegendaryActivity: 1750Merit: 1007 Re: Guild pool a 51% threat? April 04, 2013, 08:17:00 PM #12 Quote from: Isokivi on April 04, 2013, 07:57:36 PM ..this is irresponsible.

6 Blocks in a row..this is irresponsible.

This isn't the first time a single pool has made 6 blocks in a row, nor will it ever be the last. Ozcoin did it before with less than 25%. BTC Guild is only at 35% of the last 2016 blocks. That's a LONG way off of 51%. ~10 TH/s would have to leave other pools and join BTC Guild (extremely unlikely), or ~15 TH/s of new speed would have to join the network and all point at BTC Guild (even less likely). This isn't the first time a single pool has made 6 blocks in a row, nor will it ever be the last. Ozcoin did it before with less than 25%. BTC Guild is only at 35% of the last 2016 blocks. That's a LONG way off of 51%. ~10 TH/s would have to leave other pools and join BTC Guild (extremely unlikely), or ~15 TH/s of new speed would have to join the network and all point at BTC Guild (even less likely). RIP BTC Guild, April 2011 - June 2015

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ModeratorLegendaryActivity: 3178Merit: 4298 Re: Guild pool a 51% threat? April 05, 2013, 10:58:29 PM #16



Here was my response:



On Fri, Apr 5, 2013 at 2:30 AM, Melvin Carvalho

<

> There was some chat on IRC about a mining pool reaching 46%

> http://blockchain.info/pools



The estimates on there may be a bit lossy.



> What's the risk of a 51% attack.



The whole fixation on "51" as a magic number is a bit confused I'll

say more below.



> I suggested that the pool itself is decentralized so you could not launch

> one



None of the pools listed there are meaningfully decentralized before

Luke whines, in theory the ones supporting GBT could be if used in a

way that no one actually uses them. P2Pool is decentralized based on

the same technology as Bitcoin itself, but it's certainly not as point

and click easy as a centralized pool.



> On IRC people were saying that the pool owner gets to choose what goes in

> the block



That is correct.



Though I'd point out the major pool ops all seem to be great folks

who care about the future of Bitcoin and the continued success of

their very profitable businesses: a 50% mining pool with a 3% fee

rakes in 54 BTC per _day_.



The more likely threat isn't that pool owners do something bad: It's

that their stuff gets hacked (again) or that they're subjected to

coercion. ... and the attacker either wants to watch the (Bitcoin)

world burn, or after raiding the pool wallet can't exploit it further

except via blockchain attacks.



> Surely with random non colliding nonces, it would be almost impossible to

> coordinate a 51% even by the owner



That makes no sense. A centralized pool is the miner, the remote

workers are just doing whatever computation it tells them to do.

Certainly these remote workers might switch to another pool if they

knew something bad was happening... but evidence suggests that this

takes days even when the pool is overtly losing money. Miners have

freely dumped all their hashpower on questionable parties (like the

infamous pirate40) with nary a question as to what it would be used

for when they were paid a premium for doing so. It seems even those

with large hardware investments are not aware of or thinking carefully

about the risks.



> It would be great to know if this is a threat or a non issue



It's important to know exactly what kind of threat you're talking

about someone with a large amount of hash-power can replace

confirmed blocks with an alternative chain that contains different

transactions. This allows them to effectively reverse and respend

their own transactions clawing back funds that perhaps had already

triggered irreversible actions.



This doesn't require some magic "51%" its just that when a miner has

>50% the attack would always be successful if they kept it up long

enough (long enough might be years if you're talking really close to

50% and he gets unlucky). Likewise, someone with a sustained

supermajority could deny all other blocks but that attack's damage

stops when they lose the supermajority or go away.



More interesting is this: An attacker with only 40% of the hashpower

can reverse six confirmations with a success rate of ~50%. There is

source for computing this at the end of the Bitcoin paper. I did a

quick and really lame conversion of his code JS so you can play with

it in a browser:



https://people.xiph.org/~greg/attack_success.html



There was a post on this subject on bitcoin-development last night, but it hasn't shown up in the archives yet.Here was my response:On Fri, Apr 5, 2013 at 2:30 AM, Melvin Carvalho melvincarvalho@gmail.com > wrote:> There was some chat on IRC about a mining pool reaching 46%The estimates on there may be a bit lossy.> What's the risk of a 51% attack.The whole fixation on "51" as a magic number is a bit confused I'llsay more below.> I suggested that the pool itself is decentralized so you could not launch> oneNone of the pools listed there are meaningfully decentralized beforeLuke whines, in theory the ones supporting GBT could be if used in away that no one actually uses them. P2Pool is decentralized based onthe same technology as Bitcoin itself, but it's certainly not as pointand click easy as a centralized pool.> On IRC people were saying that the pool owner gets to choose what goes in> the blockThat is correct.Though I'd point out the major pool ops all seem to be great folkswho care about the future of Bitcoin and the continued success oftheir very profitable businesses: a 50% mining pool with a 3% feerakes in 54 BTC per _day_.The more likely threat isn't that pool owners do something bad: It'sthat their stuff gets hacked (again) or that they're subjected tocoercion. ... and the attacker either wants to watch the (Bitcoin)world burn, or after raiding the pool wallet can't exploit it furtherexcept via blockchain attacks.> Surely with random non colliding nonces, it would be almost impossible to> coordinate a 51% even by the ownerThat makes no sense. A centralized pool is the miner, the remoteworkers are just doing whatever computation it tells them to do.Certainly these remote workers might switch to another pool if theyknew something bad was happening... but evidence suggests that thistakes days even when the pool is overtly losing money. Miners havefreely dumped all their hashpower on questionable parties (like theinfamous pirate40) with nary a question as to what it would be usedfor when they were paid a premium for doing so. It seems even thosewith large hardware investments are not aware of or thinking carefullyabout the risks.> It would be great to know if this is a threat or a non issueIt's important to know exactly what kind of threat you're talkingabout someone with a large amount of hash-power can replaceconfirmed blocks with an alternative chain that contains differenttransactions. This allows them to effectively reverse and respendtheir own transactions clawing back funds that perhaps had alreadytriggered irreversible actions.This doesn't require some magic "51%" its just that when a miner has>50% the attack would always be successful if they kept it up longenough (long enough might be years if you're talking really close to50% and he gets unlucky). Likewise, someone with a sustainedsupermajority could deny all other blocks but that attack's damagestops when they lose the supermajority or go away.More interesting is this: An attacker with only 40% of the hashpowercan reverse six confirmations with a success rate of ~50%. There issource for computing this at the end of the Bitcoin paper. I did aquick and really lame conversion of his code JS so you can play withit in a browser:

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Poor impulse control.







DonatorLegendaryActivity: 2058Merit: 1007Poor impulse control. Re: Guild pool a 51% threat? April 07, 2013, 04:49:08 AM #17 Quote from: gmaxwell on April 05, 2013, 10:58:29 PM



Here was my response:



On Fri, Apr 5, 2013 at 2:30 AM, Melvin Carvalho

<

> There was some chat on IRC about a mining pool reaching 46%

> http://blockchain.info/pools



The estimates on there may be a bit lossy.



> What's the risk of a 51% attack.



The whole fixation on "51" as a magic number is a bit confused I'll

say more below.



> I suggested that the pool itself is decentralized so you could not launch

> one



None of the pools listed there are meaningfully decentralized before

Luke whines, in theory the ones supporting GBT could be if used in a

way that no one actually uses them. P2Pool is decentralized based on

the same technology as Bitcoin itself, but it's certainly not as point

and click easy as a centralized pool.



> On IRC people were saying that the pool owner gets to choose what goes in

> the block



That is correct.



Though I'd point out the major pool ops all seem to be great folks

who care about the future of Bitcoin and the continued success of

their very profitable businesses: a 50% mining pool with a 3% fee

rakes in 54 BTC per _day_.



The more likely threat isn't that pool owners do something bad: It's

that their stuff gets hacked (again) or that they're subjected to

coercion. ... and the attacker either wants to watch the (Bitcoin)

world burn, or after raiding the pool wallet can't exploit it further

except via blockchain attacks.



> Surely with random non colliding nonces, it would be almost impossible to

> coordinate a 51% even by the owner



That makes no sense. A centralized pool is the miner, the remote

workers are just doing whatever computation it tells them to do.

Certainly these remote workers might switch to another pool if they

knew something bad was happening... but evidence suggests that this

takes days even when the pool is overtly losing money. Miners have

freely dumped all their hashpower on questionable parties (like the

infamous pirate40) with nary a question as to what it would be used

for when they were paid a premium for doing so. It seems even those

with large hardware investments are not aware of or thinking carefully

about the risks.



> It would be great to know if this is a threat or a non issue



It's important to know exactly what kind of threat you're talking

about someone with a large amount of hash-power can replace

confirmed blocks with an alternative chain that contains different

transactions. This allows them to effectively reverse and respend

their own transactions clawing back funds that perhaps had already

triggered irreversible actions.



This doesn't require some magic "51%" its just that when a miner has

>50% the attack would always be successful if they kept it up long

enough (long enough might be years if you're talking really close to

50% and he gets unlucky). Likewise, someone with a sustained

supermajority could deny all other blocks but that attack's damage

stops when they lose the supermajority or go away.



More interesting is this: An attacker with only 40% of the hashpower

can reverse six confirmations with a success rate of ~50%. There is

source for computing this at the end of the Bitcoin paper. I did a

quick and really lame conversion of his code JS so you can play with

it in a browser:



https://people.xiph.org/~greg/attack_success.html





There was a post on this subject on bitcoin-development last night, but it hasn't shown up in the archives yet.Here was my response:On Fri, Apr 5, 2013 at 2:30 AM, Melvin Carvalho melvincarvalho@gmail.com > wrote:> There was some chat on IRC about a mining pool reaching 46%The estimates on there may be a bit lossy.> What's the risk of a 51% attack.The whole fixation on "51" as a magic number is a bit confused I'llsay more below.> I suggested that the pool itself is decentralized so you could not launch> oneNone of the pools listed there are meaningfully decentralized beforeLuke whines, in theory the ones supporting GBT could be if used in away that no one actually uses them. P2Pool is decentralized based onthe same technology as Bitcoin itself, but it's certainly not as pointand click easy as a centralized pool.> On IRC people were saying that the pool owner gets to choose what goes in> the blockThat is correct.Though I'd point out the major pool ops all seem to be great folkswho care about the future of Bitcoin and the continued success oftheir very profitable businesses: a 50% mining pool with a 3% feerakes in 54 BTC per _day_.The more likely threat isn't that pool owners do something bad: It'sthat their stuff gets hacked (again) or that they're subjected tocoercion. ... and the attacker either wants to watch the (Bitcoin)world burn, or after raiding the pool wallet can't exploit it furtherexcept via blockchain attacks.> Surely with random non colliding nonces, it would be almost impossible to> coordinate a 51% even by the ownerThat makes no sense. A centralized pool is the miner, the remoteworkers are just doing whatever computation it tells them to do.Certainly these remote workers might switch to another pool if theyknew something bad was happening... but evidence suggests that thistakes days even when the pool is overtly losing money. Miners havefreely dumped all their hashpower on questionable parties (like theinfamous pirate40) with nary a question as to what it would be usedfor when they were paid a premium for doing so. It seems even thosewith large hardware investments are not aware of or thinking carefullyabout the risks.> It would be great to know if this is a threat or a non issueIt's important to know exactly what kind of threat you're talkingabout someone with a large amount of hash-power can replaceconfirmed blocks with an alternative chain that contains differenttransactions. This allows them to effectively reverse and respendtheir own transactions clawing back funds that perhaps had alreadytriggered irreversible actions.This doesn't require some magic "51%" its just that when a miner has>50% the attack would always be successful if they kept it up longenough (long enough might be years if you're talking really close to50% and he gets unlucky). Likewise, someone with a sustainedsupermajority could deny all other blocks but that attack's damagestops when they lose the supermajority or go away.More interesting is this: An attacker with only 40% of the hashpowercan reverse six confirmations with a success rate of ~50%. There issource for computing this at the end of the Bitcoin paper. I did aquick and really lame conversion of his code JS so you can play withit in a browser:

This was a really helpful post, gmaxwell. It made a nice and easy read of the ideas behind this type of attack - you might consider stickying the essentials somewhere.



It might also be an idea if someone renamed this attack to something that doesn't include the number "51" in the name. This was a really helpful post, gmaxwell. It made a nice and easy read of the ideas behind this type of attack - you might consider stickying the essentials somewhere.It might also be an idea if someone renamed this attack to something that doesn't include the number "51" in the name.

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