Double spending has already happened when will protocol be fixed?

[cryptopaths]

Double spending has already happened and will continue to do so the 51% attack feared by many is just a larger scale also many people theorize Gash has 51%+ currently anyway. My question is when will the 51%/double spending problem be fixed? Why aren't p2p pools implemented better to mitigate this? When will the devs make an effort to fix this obvious flaw? It's common knowledge that double spending has happened and if there is really any naive people I'll build up some sources and put some links here.

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[franky1]

Double spending has already happened and will continue to do so the 51% attack feared by many is just a larger scale also many people theorize Gash has 51%+ currently anyway. My question is when will the 51%/double spending problem be fixed? Why aren't p2p pools implemented better to mitigate this? When will the devs make an effort to fix this obvious flaw? It's common knowledge that double spending has happened and if there is really any naive people I'll build up some sources and put some links here.

double spend ATTEMPTS have happened. but show me the actual tx's of a successful double spend (injection of fresh coins that were not mined)

[Soros Shorts]

I guess a definition of "Double Spend" is required here. At the very least, the number of confirmed blocks between the first and second spend attempts needs to be specified.

[12648430]

double spend ATTEMPTS have happened. but show me the actual tx's of a successful double spend (injection of fresh coins that were not mined)

That's not what double-spending is.

Successful double spends happen, usually against people who accept 0- or 1-confirmation transactions in situations where they have no recourse. The solution is not to do that.

[franky1]

I guess a definition of "Double Spend" is required here. At the very least, the number of confirmed blocks between the first and second spend attempts needs to be specified.

the addition of the word "attempt" is needed....

id love to see 2 output tx's which used the same original coin input, to BOTH show confirmations where the coins can then be moved on and respent, instead of one of the output tx's showing as stuck in a no confirm limbo

That's not what double-spending is.

Successful double spends happen, usually against people who accept 0- or 1-confirmation transactions in situations where they have no recourse. The solution is not to do that.

there are no blockchain/bitcoin double spend successes. there are just recipient acceptance failures (human error)

[Peter R]

Last time we polled the community to determine the accepted definition of "successful double spend," the results were as follows:

[franky1]

Last time we polled the community to determine the accepted definition of "successful double spend," the results were as follows:

35 voters is not the community determining the definition.

i can get 35 people to determine that superman is real and that kryptonite can be bought for $12 at a 7-11

edit:
a double spend:
imagine a bank note, you give it to a cashier. and buy a ice-tea. the cashier in a moment of panic accidently gives you back that whole banknote back as change. you then buy a cake from another shop. at the end of the day the ice-tea cashier is missing a bank note. and is at a loss. because there is only one bank note that has been spent twice

human error counterfeit:
however. what most people perceive as a bitcoin double spend is where the sender sends 2 exact same bank notes (copies) one to a ice-tea shop and one to a cake shop. where only 1 of those recipient confirms its a legit bank note which thy can re-use later, and the other realises they got a dud counterfeit that will never be confirmed as a real bank note that they can never then spend later.

so its not a double spend.. its a human error to not confirm counterfeits

[keithers]

Given that BTC is still so new, I think the network has done a very good job preventing double spends.   No new system is ever going to be perfect, but the one we have going so far has worked far better than anyone probably could have initially imagined...

[kjj]

Last time we polled the community to determine the accepted definition of "successful double spend," the results were as follows:

Nonsense.  The blockchain defines the order of transactions.  If we had some way to determine which transaction was "broadcast first", we wouldn't bother with all of the hashing.

[cryptopaths]

Last time we polled the community to determine the accepted definition of "successful double spend," the results were as follows:

35 voters is not the community determining the definition.

i can get 35 people to determine that superman is real and that kryptonite can be bought for $12 at a 7-11

You're still ignoring what the community defines as double spending just to twist this around and give your argument more credibility. When your comment isn't what I'm talking about and you know it.

[franky1]

Double spending has already happened and will continue to do so the 51% attack feared by many is just a larger scale also many people theorize Gash has 51%+ currently anyway. My question is when will the 51%/double spending problem be fixed? Why aren't p2p pools implemented better to mitigate this? When will the devs make an effort to fix this obvious flaw? It's common knowledge that double spending has happened and if there is really any naive people I'll build up some sources and put some links here.

Please put some links.

he wont link you, because there are no transactions that have confirmations where it was the same exact coin used twice. there are however many times there the same 'coin' is on more then one transaction, but one is revealed as a fake (unconfirmed). its not a bug or a protocol issue. its a human error for not doing any checks to confirm its real (zero confirm)

[Peter R]

Nonsense.  The blockchain defines the order of transactions.  If we had some way to determine which transaction was "broadcast first", we wouldn't bother with all of the hashing.

Imagine that an observer creates two transactions, A and B, that both spend the same outputs. He structures A so that it sends a few bits to an on-chain miner because he knows Eligius won't accept it into mempool.  He broadcasts A to the network at t=0 s according to his clock and then broadcasts B at t=10 s.  Eligius finds the next block and B gets mined into the blockchain instead of A.  

For the observer to deny that A was actually sent first is to deny objective reality.  Transaction A was sent first!  The fact that the rest of the world has no way to prove this fact does not make it false.  

[Peter R]

35 voters is not the community determining the definition.

I agree.  The word "determine" was too strong for this small of a poll.  But I think it is correct: IMO most people mean definition 2 when they say "successful double spend."

But the point I was trying to make is valid: very few people use your definition.  According to your definition, double-spends are impossible.  But if they are impossible, we wouldn't worry about them.  So your definition is not useful because people do worry about double spends.  

To me, definition 3 is correct.  A "successful double spend" occurs when an attacker is able to spend the same coins twice.  For example, if he uses 5000 bits to buy a coffee at Starbucks, and then (for example by using Peter Todd's replace by fee tools) uses those same coins to buy lunch, then that's a "successful double spend."  Either Starbucks or the lunch restaurant has lost out on 5000 bits because the attacker was able to "spend them twice."

[tl121]

For the observer to deny that A was actually sent first is to deny objective reality.

There is no such thing as objective reality in a distributed system (unless one is God).  There are two problems here, first physical reality itself is not totally ordered, and second, each person has access to only his individual sense perceptions and measurements unless he trusts others.  In short, your "objective" reality is not mine, especially if I don't happen to trust you.  (From recent forum posts, it would seem prudent not to trust a large number of posters, so please don't take my remark personally.)

It is logically impossible to achieve reliable consensus in a distributed asynchronous system.  This was proven decades ago by Nancy Lynch et. al., and the proof didn't even require malicious nodes, just nodes that could fail or run slowly. Bitcoin doesn't circumvent this proof.  That's because Bitcoin does not ever give 100% confirmation that a transaction was committed.  Bitcoin does not and can not do what is logically impossible. One can circumvent this situation by positing the existence of a reliable central authority who controls the network and serves as "the decider", but then everyone will have to trust this "decider". (And when this "decider" goes "out to lunch" one will still have to wait to see if one's transaction was confirmed.)   This is not what bitcoin is about.

One can make a case, possibly a good case, that the bitcoin protocol can be improved to minimize the time constants involved, which are presently nowhere near the underlying physical limits because each node does extensive computation prior to forwarding transactions and blocks.  But this is not going to change the underlying situation, which is that there simply is no such thing as "objective reality" just a ceaseless flow of events that are relative to time, place and person.

[Peter R]

For the observer to deny that A was actually sent first is to deny objective reality.

There is no such thing as objective reality in a distributed system (unless one is God)...

You're missing the point.  I'm talking about what is true in reality and not about the limitations of a distributed consensus system.  

If Bob throws rock A into the lake and 10 seconds later throws rock B into the lake, then he threw rock A into the lake first.  For Bob to deny this fact is to deny objective reality.  Alice might not be able to confirm this fact, but it is still true.

Bitcoin is a distributed system designed to achieve consensus on the ordering of competing transactions.  If the network is 100% objective and if information flows instantly and accurately, then the order between physical reality and the blockchain will be preserved perfectly.  But we don't have 100% objectivity due to attackers, so proof-of-work is used to force them to expend resources in this reality to influence the order agreed upon by the network.  Mining is useful because it translates a fact of nature into a fact of mathematics, thereby providing a tether to what is objectively true.  Still, if the attacker gains 51% of the network hashrate and burns sufficient resources in physical reality, he can freely spend the same coins for as long as he can fool people into thinking the network is still objective.    

This also explains the history-rewrite problem (nothing-at-stake) that proof-of-stake systems suffer from.  Because there is no tether to objective reality, an attacker can rewrite history for very little real cost.    

[shorena]

There are double spends from time to time.

You can find some here. https://blockchain.info/double-spends

They usually come from orphaned blocks though. What I understand as a doublespend is:

Transaction A spends coins from A₁ to B₁ and gets confirmed at least once. So A is in one block and there have been 0 or more blocks after this block.
Now if this block or the chain of blocks after it get orphaned and the identical transaction A is in another block, thats no double spend, because the coins have been send to the very samd B¹ it just took them longer.
A successfull doublespend would be a new transaction E which sends coins from A₁ to E₁.

Why is this a double spend?

Because whoever made A could have gotten some good from whoever controls B₁. The owner of B₁ has no coins and no goods, thus the coins can be spend again (twice, thus the word doublespend). With the transaction E the attacker makes sure that the old transaction A can not be confirmed because the inputs have been used otherwise, thus A is no longer a valid TX.

[tl121]

I'm talking about what is true in reality

Bob says he threw one rock before the other. But perhaps he threw it higher or further from Alice and she heard the second one splash first.  Charlie wasn't there but he heard what Bob said and what Alice said. Who should Charlie trust?

Mathematically, the ordering of events in a distributed system is a partial ordering. There is a total ordering of events at individual nodes and a causal ordering that a rock doesn't splash before it was thrown.  That's it. This was described by Leslie Lamport back in 1978.

http://www.stanford.edu/class/cs240/readings/lamport.pdf

[franky1]

no one can show a true double spend where a single input has 2 outputs which both have confirmations.

the double spend as people call it is not a bug on the protocol. the protocol has no double spend bugs. the bug is human error.. lazyness to not do checks and not wait for confirmations.

bitcoin is a thing of beauty that truly works, yet humans choose to ignore the rules of bitcoin, humans choose to aimlessly accept unconfirmed payments, humans choose to send out payments twice because someone complains they never received the funds.

you cant fix a human no matter what code you put in its way.

even if new code was added to somehow prevent the relaying of a tx input twice.. humans would find a way to be stupid and lose funds by ignoring certain aspects of bitcoins function

[kjj]

No, Bob never said anything to anyone in my example.  He simply threw rock A into the lake, and then 10 seconds later he threw rock B into the lake.  This means that he threw rock A first.  If you disagree, then you're arguing that X != X.  If something happened then it happened.

If Charlie trusts Alice who claims that Bob threw rock B first, then Charlie's opinion doesn't change the fact the Bob actually threw rock A first.  Charlie and Alice could convince the entire world that Bob threw rock B first, and everyone might call Bob a liar.  But if he threw rock A first then he threw rock A first.  

Objective reality exists independent of our perception of it.  

Einstein is snickering at you from his grave.

Objective reality is like a platonic ideal of a sphere or a straight line.  One might exist, but you'll never see anything better than an approximation.  When time gets involved, relativity says that when information is constrained to finite speeds, like it is in our universe, even the approximations are personal to each observer.

At any rate, all that you can accomplish with this sophistry is to swap the labels on the problem around.

[zimmah]

Double spending has already happened and will continue to do so the 51% attack feared by many is just a larger scale also many people theorize Gash has 51%+ currently anyway. My question is when will the 51%/double spending problem be fixed? Why aren't p2p pools implemented better to mitigate this? When will the devs make an effort to fix this obvious flaw? It's common knowledge that double spending has happened and if there is really any naive people I'll build up some sources and put some links here.

P2P pools are not as easy as joining ghash.

More pools like ghash should be created, until that happens ghash will continue to be the facebook of mining pools.