It's about time to turn off PoW mining

[achimsmile]

POS has one fundamental flaw. Stake does not equal exposure as pirateat40 proved back in 2011 / 2012 https://bitcointalk.org/index.php?topic=50822.0. Show me a POS system that can deal with pirate.

Edit: Without the help of the US Government.

Could you elaborate? I'm not sure what you mean.

Could you describe attack scenario in details? After reproducing it in simulation we would like to pay you pretty good bounty

P.S. Good description on practical impossibility of N@S by JordanLee http://www.peercointalk.org/index.php?topic=2976.msg27303#msg27303

I will elaborate on the idea against nxt.
But that link you sent regarding PPC is not about practical impossibility of N@S. It's only about practical impossiblity of the particular attack that the writer describes. This was proven by my attack on APEX. Also, it has some flaws:

"They must wait 90 days to get another optimal chance to attack after a failed attempt"

is wrong, if you mine your chain in private and publish it only when it has accumulated more work than the main chain then you can attempt this after every block.

"If you buy 1% of Peercoins and put them all in the same output (similar to an address), you might have about a 3% chance of finding the next block."

is also wrong: 1% gives you about 20% chance of a block. 5% guarantees success.

So it I understand this correctly an attacker could borrow rather than buy say 10% of the target POS coin. This could be done for example using a pirateat40 type scheme. Sell half of the borrowed POS coins short, and use the remaining 5% of the borrowed coins to launch the attack. This would cause the price of the coin to collapse creating massive profits for our short seller / attacker. There is some real Bitcoin history here that is a must for anyone either attacking or defending a POS coin. Here is a good place to start. https://bitcointalk.org/index.php?topic=50822.0. pirateat40 failed with Bitcoin but Bitcoin is POW! I can just imagine what would have happened to Bitcoin if pirateat40 could have used the borrowed XBT to launch an attack on the Bitcoin blockchain. This would indeed have been the case if Bitcoin had been POS. 

https://bitcointalk.org/index.php?topic=897488.msg10178740#msg10178740

Ah, ok. Since he only attacked a dead coin and did it by building up coin age, and coin age is not used in all PoS systems, I would argue that not all PoS coins are susceptible to this attack.

But I'm interested to hear details from him.

I think I know what you mean now. "If 50% of all stake is minting/forging, you only need 26% of total stake to do a 51% attack", right?

[achimsmile]

I would say that POS requires a centralized authority to prevent collapse.

That is a statement, not an argument.
Who is this authority?

[inBitweTrust]

I would say that POS requires a centralized authority to prevent collapse.

That is a statement, not an argument.
Who is this authority?

In both open source versions of PoS and PoW the authority is split between miners or stakeholders/ users or nodes / and developers.

The difference is within PoW the target is always moving and is wasteful (both a valid criticism and a strength) so the power structures are always shifting based upon technological development and business advantages. This has been proven by changes in not just with mining pools but asic manufacturers, and miners themselves over time. Miners are forced to distribute most their coins to cover business and electrical costs.

With PoS the largest shareholders are fixed targets who are less likely to be unseated due to not being dependent upon constantly reinventing their business model and technology to be competitive. Stakeholders can choose to horde or sell off their coins from forging/stake holding thus ensuring some early adopters remain in positions of authority.

Rather than discussing changing Bitcoin over to PoS, I think we should merely add a TaPoS layer or sidechain to PoW to further strengthen Bitcoin's security and allow for quicker confirmations. The environmental concerns will eventually be addressed anyways by the exponentially decreasing block reward and market forces.

Another thing that I like about PoW that is rarely discussed is that it is a technological arms race that spurs ASIC development and cooling technologies.

[ArticMine]

I am dealing with a much more fundamental problem with POS namely that that an attacker can build up a very significant stake in the coin while at the same time having a large short exposure to the coin. This creates a situation where the attacker has a large stake and a vested interest in the collapse of the coin. Pirateat40 is relevant here because he did just that with Bitcoin by borrowing large quantities of XBT and selling some of them short. He also tried very hard to cause the price of Bitcoin to fall. If one combines this with the attack that cynicSOB is referring to then the effect is significantly magnified. I suspect cynicSOB is referring to a combination of the fact that a very significant portion of the coins are not staking, and a time warp attack. Time warp attacks have been used against POW coins that have low hashrates, and can be defended against by the use of time stamping. Essentially saying that one does not accept a longer chain that involves reorganization after a certain number of blocks.  

As for an authority one needs an authority to prevent the massive borrowing of the POS coin by for example a ponzi scheme. In the pirateat40 case this was the US SEC and the US Courts.

[ArticMine]

...
With PoS the largest shareholders are fixed targets who are less likely to be unseated due to not being dependent upon constantly reinventing their business model and technology to be competitive. Stakeholders can choose to horde or sell off their coins from forging/stake holding thus ensuring some early adopters remain in positions of authority.
...

No. With POS that largest "stakeholders" can in fact have a large short position, and have a vested interest in the collapse of the coin. There is no requirement in POS that one owns the coin in order to stake it.

[kodtycoon]

...
With PoS the largest shareholders are fixed targets who are less likely to be unseated due to not being dependent upon constantly reinventing their business model and technology to be competitive. Stakeholders can choose to horde or sell off their coins from forging/stake holding thus ensuring some early adopters remain in positions of authority.
...

No. With POS that largest "stakeholders" can in fact have a large short position, and have a vested interest in the collapse of the coin. There is no requirement in POS that one owns the coin in order to stake it.

how on earth did you come to the conclusion that you dont need the coins to stake? :/

[ArticMine]

...
how on earth did you come to the conclusion that you dont need the coins to stake? :/

You have the coins in your possession and stake them, they are just not yours. It is no different from borrowing a car and driving it. The car is in your possession but it does not belong to you.

[kodtycoon]

...
how on earth did you come to the conclusion that you dont need the coins to stake? :/

You have the coins in your possession and stake them, they are just not yours. 

so your talking about borrowing coins?

do you honestly think its even remotely possible to borrow 10% of any coins total cap? id love to see you try and borrow even 1% of bitcoin lol

[inBitweTrust]

...
how on earth did you come to the conclusion that you dont need the coins to stake? :/

You have the coins in your possession and stake them, they are just not yours. It is no different from borrowing a car and driving it. The car is in your possession but it does not belong to you.

With crypto currency, those who control the private keys technically own the currency, thus allowing a bank or exchange to control the private keys is actually a gift that you hope will be repaid based upon faith in them or regulators.

so your talking about borrowing coins?

do you honestly think its even remotely possible to borrow 10% of any coins total cap? id love to see you try and borrow even 1% of bitcoin lol

He is probably suggesting such an attack is easier with PoS than PoW , and he is correct.

[ArticMine]

...
how on earth did you come to the conclusion that you dont need the coins to stake? :/

You have the coins in your possession and stake them, they are just not yours. 

so your talking about borrowing coins?

do you honestly think its even remotely possible to borrow 10% of any coins total cap? id love to see you try and borrow even 1% of bitcoin lol

Pirateat40 came very close to doing just that. The liabilities of "First Pirate Savings and Trust" later called "Bitcoin Savings and Trust" approached 800.000 XBT when the total XBT emission was around 8,000,000 XBT. More recently we have MTGox. So a variant of this attack would be to "Gox" the POS coin. Keep in mind that only 5% is needed for the attack according to cynicSOB. The rest were sold short over time.

[ivonna]

...
how on earth did you come to the conclusion that you dont need the coins to stake? :/

You have the coins in your possession and stake them, they are just not yours. It is no different from borrowing a car and driving it. The car is in your possession but it does not belong to you.

With crypto currency, those who control the private keys technically own the currency, thus allowing a bank or exchange to control the private keys is actually a gift that you hope will be repaid based upon faith in them or regulators.

so your talking about borrowing coins?

do you honestly think its even remotely possible to borrow 10% of any coins total cap? id love to see you try and borrow even 1% of bitcoin lol

He is probably suggesting such an attack is easier with PoS than PoW , and he is correct.

With NXT you can actually lease the coins that you control the private keys to a pool that will use many coins to "mine" and the reward will be split between participants based on how much they each contribute (in terms of number of coins). You would still remain in control of the coins the entire time and can send them freely.

The problem is that you cannot force the pool operator to send you the reward (although this is similar to PoW mining with the exception of p2pool)

[ArticMine]

POS is based on the premise that people will not lend or borrow money. This is its fundamental flaw.

[inBitweTrust]

With NXT you can actually lease the coins that you control the private keys to a pool that will use many coins to "mine" and the reward will be split between participants based on how much they each contribute (in terms of number of coins). You would still remain in control of the coins the entire time and can send them freely.

The problem is that you cannot force the pool operator to send you the reward (although this is similar to PoW mining with the exception of p2pool)

Yes, it is unfortunate that NxT took this footnote from Bitcoin and incorporated this security weakness.

[achimsmile]

POS is based on the premise that majority of all people will not lend or borrow money to the same guy. This is its fundamental flaw.

FIFY.

Bitcoin is based on the premise that that majority of all miners will not lend their mining power to the same mining pool.
Which flaw is more fundamental?

[ArticMine]

POS is based on the premise that majority of all people will not lend or borrow money to the same guy. This is its fundamental flaw.

FIFY.

Bitcoin is based on the premise that that majority of all miners will not lend their mining power to the same mining pool.
Which flaw is more fundamental?

POS of course. I can change the pool settings on my XBT miner any time I want. Now compare this with getting repaid by pirateat40 or MTGox.

[VectorChief]

PoW mining is the only way to keep the money system running without a permanent overseeing authority, as miners get into their positions by being better than others, rather than by decree like in fiat or PoS.

Either you mean that PoS systems don't run (which I doubt),
or you mean that PoS systems are controlled by a permanent overseeing authority.
So, who is this authority?

First they run, then they saturate, then they don't run.
Then PoW wins!

[inBitweTrust]

POS is based on the premise that majority of all people will not lend or borrow money to the same guy. This is its fundamental flaw.

Only 10% is needed.
With crypto currency how would you know you are lending to a million people or 1 person?

Bitcoin is based on the premise that that majority of all miners will not lend their mining power to the same mining pool.
Which flaw is more fundamental?

It is effortless to switch pools and history has proven that pools will fall out of favor quickly if an attack seems eminent or occurs. The power is still in control of the people with the actual hardware and burning the electricity ultimately. With PoW the power isn't even held as a monopoly with the ASIC manufacturers as another company could out compete the existing companies with better efficiency or innovative products at any moment.

[ArticMine]

This discussion gives a good perspective on POS. The security of a POS network is ultimately based upon the credit worthiness of the likes of Trendon Shavers and Mark Karpelès

[drkman]

...
With PoS the largest shareholders are fixed targets who are less likely to be unseated due to not being dependent upon constantly reinventing their business model and technology to be competitive. Stakeholders can choose to horde or sell off their coins from forging/stake holding thus ensuring some early adopters remain in positions of authority.
...

No. With POS that largest "stakeholders" can in fact have a large short position, and have a vested interest in the collapse of the coin. There is no requirement in POS that one owns the coin in order to stake it.

In general if you hold 1 billion US Dollars, it's not in your best financial interests to cause an action to plummet the price of the US Dollar.  Same for POS coins.  Also, please provide an actual example of a large short staking a POS coin by being short to successfully attack a POS coin.

[inBitweTrust]

In general if you hold 1 billion US Dollars, it's not in your best financial interests to cause an action to plummet the price of the US Dollar.  Same for POS coins.  

Banks and whales commit these types of attacks all the time on Forex.

Also, please provide an actual example of a large short staking a POS coin by being short to successfully attack a POS coin.

How would you know that these attacks haven't already been committed multiple times?