Do you think another 51% attack will happen?

[BitcoinNoob12345]

Like when the big money starts to get involved do you think the chances are it will happen again and at a much larger scale?
If it does do you think people might migrate to other alts or other types of coins like peercoin?

[Sindelar1938]

Not going to happen, mate
But if it did, expect mass migration to other alts...

[DannyHamilton]

Another?

Apparently I wasn't paying attention.  When was the previous attack?

[CIYAM]

Apparently I wasn't paying attention.  When was the previous attack?

Exactly - there has not been such an attack on Bitcoin (only 1 alt I think has been attacked in this way).

[Sutters Mill]

Gnash.io came close by almost having 51% of bitcoins mining power in their pool but they've said they're putting measures in place to make sure it never reaches 51%. If it was a more unscrupulous group then maybe things could have gone badly but who knows if it will happen in future. Remember that if someone does do it, their own bitcoins would likely become worthless too.

[DannyHamilton]

Gnash.io came close by almost having 51% of bitcoins mining power in their pool but they've said they're putting measures in place to make sure it never reaches 51%. If it was a more unscrupulous group then maybe things could have gone badly but who knows if it will happen in future. Remember that if someone does do it, their own bitcoins would likely become worthless too.

Almost coming close to controlling 51% of the hashing power for a short time is not an "attack".

If they were unscrupulous, it is rather likely that many miners would quickly leave the pool and they would then drop back to a lower percentage of the network hashing power.

During that short amount of time that they could have unscrupulously controlled 51% of the hashing power, what unscrupulous thing exactly do you think they might have done?

[MA3A]

51% could of happen about a week or two ago. The biggest pool gnash.io
( https://blockchain.info/pools?timespan=4days ) could of done that if wanted, they are smart and went opposite way - not exploiting this vulnerability.
If interested you can read a bit more here http://arxiv.org/abs/1311.0243
BTC guild is next biggest pool… basically once some one reaches certain computing power they could of employ this.
As other mates suggested it would be very unwise to exploit it, as it would end BTC on the spot, imho.

[Sutters Mill]

Gnash.io came close by almost having 51% of bitcoins mining power in their pool but they've said they're putting measures in place to make sure it never reaches 51%. If it was a more unscrupulous group then maybe things could have gone badly but who knows if it will happen in future. Remember that if someone does do it, their own bitcoins would likely become worthless too.

Almost coming close to controlling 51% of the hashing power for a short time is not an "attack".

If they were unscrupulous, it is rather likely that many miners would quickly leave the pool and they would then drop back to a lower percentage of the network hashing power.

During that short amount of time that they could have unscrupulously controlled 51% of the hashing power, what unscrupulous thing exactly do you think they might have done?

Well I'm sure you've read the same things everyone has about how it works and what 'extra powers' they would have had. A quick google could give the answers you're looking for.

[trumbadera]

Thats why I preffer mine at smaller pools and have other backup pools.
There is not reason to mine at biggest pools

[DannyHamilton]

Gnash.io came close by almost having 51% of bitcoins mining power in their pool but they've said they're putting measures in place to make sure it never reaches 51%. If it was a more unscrupulous group then maybe things could have gone badly but who knows if it will happen in future. Remember that if someone does do it, their own bitcoins would likely become worthless too.

Almost coming close to controlling 51% of the hashing power for a short time is not an "attack".

If they were unscrupulous, it is rather likely that many miners would quickly leave the pool and they would then drop back to a lower percentage of the network hashing power.

During that short amount of time that they could have unscrupulously controlled 51% of the hashing power, what unscrupulous thing exactly do you think they might have done?

Well I'm sure you've read the same things everyone has about how it works and what 'extra powers' they would have had. A quick google could give the answers you're looking for.

I've studied bitcoin for over 2 years.  I know exactly what "extra powers" they would have had.  I also know that "a quick google" will turn up a lot of rumors, mistaken beliefs, and complete FUD.

That's why I specifically asked "what unscrupulous thing exactly do you think they might have done?"

If you are fearing things that aren't possible, then I'd have an opportunity to educate and help understand that having a bit over 50% of the network hash power for a short period of time does not really allow the person in control to accomplish much that needs to be feared.

If someone controls more than 50% of the network hashing power for a very long time, or if they control significantly more than 50%, then they can begin to be a bit more destructive.  However, it is extremely likely that many miners will switch pools if they feel that Ghash.io controls too much of the hashing power for too long.

[CryptoReaper]

I worry that a 51% attack on Bitcoin is inevitable. It is frightening to think that an organization could buy up enough mining equipment to fork the blockchain.

Perhaps that is implausible, but it's something we all have to be wary of, as that hypothetical organization could destroy one of the main pillars of Bitcoin, decentrlization.

[Sutters Mill]

Gnash.io came close by almost having 51% of bitcoins mining power in their pool but they've said they're putting measures in place to make sure it never reaches 51%. If it was a more unscrupulous group then maybe things could have gone badly but who knows if it will happen in future. Remember that if someone does do it, their own bitcoins would likely become worthless too.

Almost coming close to controlling 51% of the hashing power for a short time is not an "attack".

If they were unscrupulous, it is rather likely that many miners would quickly leave the pool and they would then drop back to a lower percentage of the network hashing power.

During that short amount of time that they could have unscrupulously controlled 51% of the hashing power, what unscrupulous thing exactly do you think they might have done?

Well I'm sure you've read the same things everyone has about how it works and what 'extra powers' they would have had. A quick google could give the answers you're looking for.

I've studied bitcoin for over 2 years.  I know exactly what "extra powers" they would have had.  I also know that "a quick google" will turn up a lot of rumors, mistaken beliefs, and complete FUD.

That's why I specifically asked "what unscrupulous thing exactly do you think they might have done?"

If you are fearing things that aren't possible, then I'd have an opportunity to educate and help understand that having a bit over 50% of the network hash power for a short period of time does not really allow the person in control to accomplish much that needs to be feared.

If someone controls more than 50% of the network hashing power for a very long time, or if they control significantly more than 50%, then they can begin to be a bit more destructive.  However, it is extremely likely that many miners will switch pools if they feel that Ghash.io controls too much of the hashing power for too long.

Appreciate it. Among other things, I also gleaned from your post that Bitcoin is more than 2 years old. I thought Coinye started this whole cryptocoin thing just recently, so that's good to know 

[DannyHamilton]

Appreciate it. Among other things, I also gleaned from your post that Bitcoin is more than 2 years old. I thought Coinye started this whole cryptocoin thing just recently, so that's good to know 

Not sure if trolling 

Just in case you're serious...

Bitcoin started in early 2009.  It is in it's 5th year. It is accepted for payment by many well known companies such as Reddit, WordPress, & Overstock.com. It is also accepted in many brick-and-mortar stores throughout the world. There is even a bitcoinstore.com that accepts ONLY bitcoin as payment.  Bitcoin has weathered some significant crises including a hack of what was the only significant exchange at the time, large scale thefts from popular web based wallet services, and a bug that caused a fork in the blockchain that lasted several hours before it was discovered and repaired.  Its continued success in the face of such disasters, as well as its vast and growing open-source developer community is a strong indication of potential future success.

Litecoin was the second crypto-currency created in 2011.  It has a loyal following and a pretty active community.  There are many who think of litecoin's financial relationship to bitcoin as analogous to silver's financial relationship to gold.

There has been a recent flood of "get rich quick!" alternative currencies (alt-coins).  Many were created by envious people who felt they "missed out" on the early days of bitcoin and who felt that if they created their own alt-coin then they could take advantage of the others that felt the same way.  Some were given silly names (probably as a joke) such as DogeCoin (doggy coin?) and Coinye (Kanye West).

Some of these alt-coins may acquire a loyal following and fill a niche market, but many will fall apart and collapse when the initial development team cashes out and abandons the project.

[Cryptopher]

Gnash.io came close by almost having 51% of bitcoins mining power in their pool but they've said they're putting measures in place to make sure it never reaches 51%. If it was a more unscrupulous group then maybe things could have gone badly but who knows if it will happen in future. Remember that if someone does do it, their own bitcoins would likely become worthless too.

Almost coming close to controlling 51% of the hashing power for a short time is not an "attack".

If they were unscrupulous, it is rather likely that many miners would quickly leave the pool and they would then drop back to a lower percentage of the network hashing power.

During that short amount of time that they could have unscrupulously controlled 51% of the hashing power, what unscrupulous thing exactly do you think they might have done?

Well I'm sure you've read the same things everyone has about how it works and what 'extra powers' they would have had. A quick google could give the answers you're looking for.

I've studied bitcoin for over 2 years.  I know exactly what "extra powers" they would have had.  I also know that "a quick google" will turn up a lot of rumors, mistaken beliefs, and complete FUD.

That's why I specifically asked "what unscrupulous thing exactly do you think they might have done?"

If you are fearing things that aren't possible, then I'd have an opportunity to educate and help understand that having a bit over 50% of the network hash power for a short period of time does not really allow the person in control to accomplish much that needs to be feared.

If someone controls more than 50% of the network hashing power for a very long time, or if they control significantly more than 50%, then they can begin to be a bit more destructive.  However, it is extremely likely that many miners will switch pools if they feel that Ghash.io controls too much of the hashing power for too long.

Appreciate it. Among other things, I also gleaned from your post that Bitcoin is more than 2 years old. I thought Coinye started this whole cryptocoin thing just recently, so that's good to know 

Lol Coinye is the bottom of the barrel stuff.

Bitcoin recently celebrated its fifth birthday, with the Genesis Block being mined on the 3rd January 2009.

[Sutters Mill]

Gnash.io came close by almost having 51% of bitcoins mining power in their pool but they've said they're putting measures in place to make sure it never reaches 51%. If it was a more unscrupulous group then maybe things could have gone badly but who knows if it will happen in future. Remember that if someone does do it, their own bitcoins would likely become worthless too.

Almost coming close to controlling 51% of the hashing power for a short time is not an "attack".

If they were unscrupulous, it is rather likely that many miners would quickly leave the pool and they would then drop back to a lower percentage of the network hashing power.

During that short amount of time that they could have unscrupulously controlled 51% of the hashing power, what unscrupulous thing exactly do you think they might have done?

Well I'm sure you've read the same things everyone has about how it works and what 'extra powers' they would have had. A quick google could give the answers you're looking for.

I've studied bitcoin for over 2 years.  I know exactly what "extra powers" they would have had.  I also know that "a quick google" will turn up a lot of rumors, mistaken beliefs, and complete FUD.

That's why I specifically asked "what unscrupulous thing exactly do you think they might have done?"

If you are fearing things that aren't possible, then I'd have an opportunity to educate and help understand that having a bit over 50% of the network hash power for a short period of time does not really allow the person in control to accomplish much that needs to be feared.

If someone controls more than 50% of the network hashing power for a very long time, or if they control significantly more than 50%, then they can begin to be a bit more destructive.  However, it is extremely likely that many miners will switch pools if they feel that Ghash.io controls too much of the hashing power for too long.

Appreciate it. Among other things, I also gleaned from your post that Bitcoin is more than 2 years old. I thought Coinye started this whole cryptocoin thing just recently, so that's good to know 

Lol Coinye is the bottom of the barrel stuff.

Bitcoin recently celebrated its fifth birthday, with the Genesis Block being mined on the 3rd January 2009.

Coinye is bottom of the barrel? Crap. Better beg for my job back!

DannyHamilton, I was trollin a bit, but I do genuinely appreciate the help.

[munchmunch]

Yes it is likely that a pool could gain 51% it is less likely that they would exploit it. I doubt bitcoin as is, is the crypo currency that makes it in the end. It will either change with new security features built in or alt coins which address it's weaknesses will take over.

[Stephen Gornick]

I worry that a 51% attack on Bitcoin is inevitable. It is frightening to think that an organization could buy up enough mining equipment to fork the blockchain.

Right now let's say that KNCMiner had ample supply of their KNC Neptunes -- one of the best rigs as far as cost/hash.  This is a hypothetical because KNC has sold out on what they accepted so far for pre-orders for future shipments.  But let's say you could place a large order and get it shipped overnight (or at least, before difficulty jumps again where you need to order more).

Total network capacity (currently, using BitcoinWatch.com): 16,116 Th/s (SHA-256).
KNC Neptune performance: 3 Th/s.
KNC Neptune cost; $10K

So you would need 5,372 of those bad boys to get 51%.  That's a $54 million investment in hardware.

Now let's say you had that capacity online today -- mining secretly on your private fork of the blockchain.

What capabilities do you have?

You can send bitcoins to an exchange(s), and then on your private fork of the blockchain you can spend those same bitcoins elsewhere (to another address you control, for instance).   But to gain any value you need to take delivery of something of value in a non-reversible manner so that after you broadcast blocks from your private fork the exchange(s) you cheated have no recourse.

How are you going to get $54 million worth of value from an exchange(s)?   Withdraw Bitcoins?  Most exchanges emply hot wallets with a limited balance (with the remaining coins held in cold storage) -- there's no way tens of millions of dollars worth of non-reversible funds will be available for withdrawal immediately.  Even if there was, they wouldn't be available for withdrawal anonymously.

So there's really no economic incentive for performing a 51% attack for the purpose of double-spending against Bitcoin.

That doesn't mean it won't or can't happen, it just means the likelihood of it occurring is pretty small.

Now take a Dogecoin.  
Total network capacity (currently, using BitInfoCharts http://bitinfocharts.com/dogecoin ): 84 Mh/s (Scrypt).
"beefy" GPU performance: 0.75 Kh/s.
"beefy" GPU cost: $450 + $75 (1/3rd of a rig, assuming 3 GPUs per mobo+power/supply rig)

So you would need 112,000 of those bad boys to get 51%.  That's a $59 million investment in hardware.    

But ..., here we have some very immature pools (in terms of infrastructure spending and experience) with a good chunk of the hashing capacity (scroll to bottom to see pie chart):
 - http://www.doktorrf.com/dogecoin/pools.html

So you DDoS DogeHouse, Multipool and Fast-Pool, and now you only need maybe 40 Mh/s to be able to make your private Dogecoin blockchain fork to be the longest.  I don't know if there still are many cheap GPUs available yet but at one time you could have bought or leased a ton of GPUs -- meaning acquiring 50,000 of them was possible.

But even this approach, with a $20M investment in hardware is not going to be a profitable attack, as you aren't going to extract $20M of value from Dogecoin through exchanges.  

So today, Dogecoin (and Litecoin) appear to have a sufficient level of mining capacity as long as no attacker has invented and produced a Scrypt-based ASIC miner.

But let's say someone put in $4M of capital and has today 40 Mh/s of hashing capacity from the first week or two of production of the scrypt-based ASIC that party has produced.   Can that party extract $4M of value from alt exchanges that support Dogecoin?  Are there enough of these exchanges allowing anonymous accounts (or did poor enough KYC where a number of fake accounts exist?).   If so, then it is entirely plausible that a 51% attack against Dogecoin (or Litecoin even) could be performed successfully, and done so at a profit.

Worse, depending on the jurisdiction that those exchanges operate, the pain could be felt even by those who didn't touch a Doegecoin or Litecoin even.  

This is because in many jurisdictions, funds sent for deposit at a crypto-currency exchange are treated as liabilities owed by the exchange.   It doesn't matter if the attack was against Dogecoin, if the exchange goes bankrupt (unable to honor all withdrawal requests) all accountholders are in the same boat.   Your bitcoins at a Cryptsy are no safer than your Litecoins ... if Litecoin is successfully attacked.

So Bitcoiners who use alt-coin exchanges should be cautious with their funds left there.     Kraken is the only exchange that has published their policy plans on what would happen should an altcoin be attacked successfully with a 51% attack (or other failure that results in losses of customer's funds):
 - http://bitcointalk.org/index.php?topic=290799.msg3126507#msg3126507

[bitbitz]

Highly doubt it!

[Moogle]

The longer it takes to happen the more unlikely it will be surely. Obviously more power will be needed as time continues as more and more power is added to the pool. Theres been a few alt coins that have died from 51% attacked early on. Pretty hard to get a new one off the ground unless you've got some serious power behind you to stop an attack like that.

[howzar]

LOL another huh? if there was a first one lol I am sure there would have been a little more discussion about it happening and few hundred press posts about the risk of BitCoins.