Blockchain split of 4 July 2015

[Amph]

I sent btc to yobit but its weird that my btc did not show up on account instead auto withdrawal to another btc address,i never encounter such thing before,does this blockchain problem or what i dont know,i only know i lost my bitcoin

that btc address to who belongs, it is your? because it sounds like your account there is hacked(your pc is infected maybe) or something, and this has nothing to do with the blockchain split

[intrader]

I sent btc to yobit but its weird that my btc did not show up on account instead auto withdrawal to another btc address,i never encounter such thing before,does this blockchain problem or what i dont know,i only know i lost my bitcoin

that btc address to who belongs, it is your? because it sounds like your account there is hacked(your pc is infected maybe) or something, and this has nothing to do with the blockchain split

I have 2fact on my account,i dont know who belongs that btc withdrawal address,its happen automatically i eve check on my account history its not recorded for deposit nor withdrawal just like its happened on blockchain

[Amph]

I sent btc to yobit but its weird that my btc did not show up on account instead auto withdrawal to another btc address,i never encounter such thing before,does this blockchain problem or what i dont know,i only know i lost my bitcoin

that btc address to who belongs, it is your? because it sounds like your account there is hacked(your pc is infected maybe) or something, and this has nothing to do with the blockchain split

I have 2fact on my account,i dont know who belongs that btc withdrawal address,its happen automatically i eve check on my account history its not recorded for deposit nor withdrawal just like its happened on blockchain

2fact with email or phone? because it looks more and more like a steal and not a related issue of the blockchain split, that will not cause such a thing btw

but i'm curious can you post the address?

[intrader]

I sent btc to yobit but its weird that my btc did not show up on account instead auto withdrawal to another btc address,i never encounter such thing before,does this blockchain problem or what i dont know,i only know i lost my bitcoin

that btc address to who belongs, it is your? because it sounds like your account there is hacked(your pc is infected maybe) or something, and this has nothing to do with the blockchain split

I have 2fact on my account,i dont know who belongs that btc withdrawal address,its happen automatically i eve check on my account history its not recorded for deposit nor withdrawal just like its happened on blockchain

2fact with email or phone? because it looks more and more like a steal and not a related issue of the blockchain split, that will not cause such a thing btw

but i'm curious can you post the address?

I am using google 2fact for android this is my btc address https://blockchain.info/address/14s5Fnf2twWsDaDvskkrBFqorrnSub7JSn
You can see there are a withdrawal at 18:48:30,i dont know why my bitcoin will sent to there

[intrader]

I sent btc to yobit but its weird that my btc did not show up on account instead auto withdrawal to another btc address,i never encounter such thing before,does this blockchain problem or what i dont know,i only know i lost my bitcoin

that btc address to who belongs, it is your? because it sounds like your account there is hacked(your pc is infected maybe) or something, and this has nothing to do with the blockchain split

I have 2fact on my account,i dont know who belongs that btc withdrawal address,its happen automatically i eve check on my account history its not recorded for deposit nor withdrawal just like its happened on blockchain

2fact with email or phone? because it looks more and more like a steal and not a related issue of the blockchain split, that will not cause such a thing btw

but i'm curious can you post the address?

I am using google 2fact for android this is my btc address https://blockchain.info/address/14s5Fnf2twWsDaDvskkrBFqorrnSub7JSn
You can see there are a withdrawal at 18:48:30,i dont know why my bitcoin will sent to there

I just received my bitcoin on yobit,seem its delayed for hours now is fine

[turvarya]

I sent btc to yobit but its weird that my btc did not show up on account instead auto withdrawal to another btc address,i never encounter such thing before,does this blockchain problem or what i dont know,i only know i lost my bitcoin

that btc address to who belongs, it is your? because it sounds like your account there is hacked(your pc is infected maybe) or something, and this has nothing to do with the blockchain split

I have 2fact on my account,i dont know who belongs that btc withdrawal address,its happen automatically i eve check on my account history its not recorded for deposit nor withdrawal just like its happened on blockchain

2fact with email or phone? because it looks more and more like a steal and not a related issue of the blockchain split, that will not cause such a thing btw

but i'm curious can you post the address?

I am using google 2fact for android this is my btc address https://blockchain.info/address/14s5Fnf2twWsDaDvskkrBFqorrnSub7JSn
You can see there are a withdrawal at 18:48:30,i dont know why my bitcoin will sent to there

I just received my bitcoin on yobit,seem its delayed for hours now is fine

Try their support first, when you encounter a problem.
I think, most services you sent Bitcoin to, don't keep it in the address you sent it do, but forward it to another address where they accumulate all inputs.
But I seriously have never checked, if that is really true. Looking at the blockchain is not an easy way to get any information. You should just do that, as a last resort.

[intrader]

I sent btc to yobit but its weird that my btc did not show up on account instead auto withdrawal to another btc address,i never encounter such thing before,does this blockchain problem or what i dont know,i only know i lost my bitcoin

that btc address to who belongs, it is your? because it sounds like your account there is hacked(your pc is infected maybe) or something, and this has nothing to do with the blockchain split

I have 2fact on my account,i dont know who belongs that btc withdrawal address,its happen automatically i eve check on my account history its not recorded for deposit nor withdrawal just like its happened on blockchain

2fact with email or phone? because it looks more and more like a steal and not a related issue of the blockchain split, that will not cause such a thing btw

but i'm curious can you post the address?

I am using google 2fact for android this is my btc address https://blockchain.info/address/14s5Fnf2twWsDaDvskkrBFqorrnSub7JSn
You can see there are a withdrawal at 18:48:30,i dont know why my bitcoin will sent to there

I just received my bitcoin on yobit,seem its delayed for hours now is fine

Try their support first, when you encounter a problem.
I think, most services you sent Bitcoin to, don't keep it in the address you sent it do, but forward it to another address where they accumulate all inputs.
But I seriously have never checked, if that is really true. Looking at the blockchain is not an easy way to get any information. You should just do that, as a last resort.

Yes,like you said its forward then back to my account again

[newb4now]

I have a hard time believing that F2pool and AntPool did this by accident.

However I also cant see their profit motive in this case since everyone knew what was happening.

It seems they just wasted time/money on the wrong chain with no benefit.

What am I missing?

[Mayer Amschel]

So are we back to normal

[DooMAD]

I have a hard time believing that F2pool and AntPool did this by accident.

However I also cant see their profit motive in this case since everyone knew what was happening.

It seems they just wasted time/money on the wrong chain with no benefit.

What am I missing?

Deliberate actions can lead to an accident, which is what happened here.  It's like knowing the route to get somewhere, but making a decision to take a shortcut and then getting hopelessly lost as a result.  Their intention was to cut corners by only doing part of the job they're supposed to be doing.  As a result they went heading off in the wrong direction and paid the consequences.  If they had done their job properly, they wouldn't have got "lost".

If blockchain.info had reported the correct blockchain all along, everyone would be laughing at those two Chinese pools who decided to (unsuccessfully) form their own version of the "blockchain" on the same day as the USA Independence celebrations... Priceless!

Blockchain.info are the ones I blame the most for this incident!  They are the ones that created confusion within the community. They didn't do their job (again?).  They have an official wallet and they are (were?) the source of blockchain statistics that people came to trust. They should have validated blocks for their users - they didn't.  Didn't they also had a bug, a few months ago, on bitcoin addresses generation, related to entropy?  bc.i should have insured that the correct blockchain (v3) was displayed on their stat page - not the (v2-based) fork - they knew better!  (and if they didn't, they do now...)

I'd be a little more cautious about placing such trust in third parties.  Saying that Blockchain.info have an "official" wallet is the same as saying that Gox had an "official" wallet because the community trusted them at one point.  It's the same mistake people make with the traditional banking sector and we should be wary about repeating it here.  At the end of the day, they're just a company and you have to decide whether to rely on them or not.  Thankfully, there were enough users who noticed the problem because they weren't trusting a third party to provide the information for them.  If everyone was relying on a third party, the mess could have been much worse.

[thebigtalk]

I'm experiencing delays when this happened. Good thing the transactions went through. Although Ive seen the notice, I still continued with the cash out and didn't wait for things to go back to normal. Now I learned my lesson and wouldn't proceed when this thing happens again.

[SebastianJu]

So does this mean we were 11% away from winning the wrong fork? Thats actually some feary news that could be created out of it.

What i dont understand... i can understand using SPV, but whats hindering the miner to mine on the new block and verify the actual block in the meanwhile. Only the miners are time sensitive, the computer controlling it most probably has spare cpu time. They could have saved quite some damage.

I think they wont disable SPV but at least implement a fix that verifies the blocks later.

[JorgeStolfi]

On a different note, here's one proposed solution for SPV nodes that does not require us to wait for 30 confirmations. Please comment on its correctness.

Let us assume that an "invalid chain" cannot be more than 50 blocks.

Step 1. We boot our SPV node "now", several days after the July 4 fork.
Step 2. We receive the mth block, say b_m. We ensure that b_m is version 3 block.
Step 3. We need to ensure that at least 50 previous blocks before b_m were also correct. We download those blocks (not just the headers).
  That is blocks b_{m-50}, b_{m-49}... b_{m-1}. Then we ensure that all were version 3, have correct signatures, etc, and correctly validate the next block (via the prevBlockHash).
Step 4. We can start counting b_m as a block of a valid chain if above checks pass.
Step 5. For any further received blocks, we follow steps 2, 4, 5 (skipping steps 1 and 3), since we have already validated 50 blocks before the "boot" block. Hence we validating only with block b_{m-1} is sufficient.

You are proposing is to modify the client so that it would do what a full node would do, only truncated to that last 50 nodes.

Just checking the version tag is not enough. This hacked client app must also know that the BIP66 rule became active at a certain block b_{n}.  Otherwise it would have to keep fetching blocks until it finds a "95% majority" event, or reaches a block before the v3 software was published.

[JorgeStolfi]

I have a hard time believing that F2pool and AntPool did this by accident.

However I also cant see their profit motive in this case since everyone knew what was happening.

It seems they just wasted time/money on the wrong chain with no benefit.

What am I missing?

According to this reddit comment, F2Pool did not even have the header of the invalid block B when they started mining on top of it.  The big pools monitor the instructions that other pools send to their members, to catch the hash of a recently mined block even before that block gets to the relay nodes.  They just did not notice (or had no way of knowing) that the hash came from a pool in the 5% that was still running v2, and therefore was likely to be invalid.

[QuestionAuthority]

They were cheating the system. Bitcoin has one variable that can't be predicted - human behavior. The system will always be flawed as long as someone sees an advantage in doing the wrong thing. Bitcoin isn't a worldwide corporation but it's players must act as if it were. Independent global actors must each do their part correctly and for the good of the whole except all of them are motivated differently. The problem with a system controlled by no one and everyone is the old adage, what's best for me is what's best.

[S4VV4S]

I have a hard time believing that F2pool and AntPool did this by accident.

However I also cant see their profit motive in this case since everyone knew what was happening.

It seems they just wasted time/money on the wrong chain with no benefit.

What am I missing?

It was an accident, or more like their speed "cheat" cost them a few thousands of dollars.
If it was intentional then there was going to be transactions included in the blocks they found.
And there were no transactions in their blocks.

[Brangdon]

So does this mean we were 11% away from winning the wrong fork?

No. The invalid chain would never have been accepted by up to date full nodes, regardless of how long it got, because it was invalid.

What i dont understand... i can understand using SPV, but whats hindering the miner to mine on the new block and verify the actual block in the meanwhile.

It sounds like they had code to do that, but disabled it because of a bug, and never got around to re-enabling it.

[Amitabh S]

On a different note, here's one proposed solution for SPV nodes that does not require us to wait for 30 confirmations. Please comment on its correctness.

Let us assume that an "invalid chain" cannot be more than 50 blocks.

Step 1. We boot our SPV node "now", several days after the July 4 fork.
Step 2. We receive the mth block, say b_m. We ensure that b_m is version 3 block.
Step 3. We need to ensure that at least 50 previous blocks before b_m were also correct. We download those blocks (not just the headers).
  That is blocks b_{m-50}, b_{m-49}... b_{m-1}. Then we ensure that all were version 3, have correct signatures, etc, and correctly validate the next block (via the prevBlockHash).
Step 4. We can start counting b_m as a block of a valid chain if above checks pass.
Step 5. For any further received blocks, we follow steps 2, 4, 5 (skipping steps 1 and 3), since we have already validated 50 blocks before the "boot" block. Hence we validating only with block b_{m-1} is sufficient.

You are proposing is to modify the client so that it would do what a full node would do, only truncated to that last 50 nodes.

Just checking the version tag is not enough. This hacked client app must also know that the BIP66 rule became active at a certain block b_{n}.  Otherwise it would have to keep fetching blocks until it finds a "95% majority" event, or reaches a block before the v3 software was published.

I agree, we need a timestamp. Version 3 started from orphaned block 363731 onwards. That block was generated at 2015-07-04 02:09:40.
which turns out to be 1435955980000 in Unix time.

We ensure that any block with timestamp greater than above is checked using the above logic with appropriate modification (example, v3 check in previous blocks stops at block 363730). This is still cheaper than running a full node.

I don't think we would need to hack bitcoinj because it gives us hooks (onBlock, etc) where we can add this logic.

[QuestionAuthority]

I have a hard time believing that F2pool and AntPool did this by accident.

However I also cant see their profit motive in this case since everyone knew what was happening.

It seems they just wasted time/money on the wrong chain with no benefit.

What am I missing?

It was an accident, or more like their speed "cheat" cost them a few thousands of dollars.
If it was intentional then there was going to be transactions included in the blocks they found.
And there were no transactions in their blocks.

See this thread: https://bitcointalk.org/index.php?topic=700411.msg11790734#msg11790734

Miners will very much be impacted by the incident. Maybe you pay for this time, but you cannot continue to cover such a large loss. What about confidence? Do you think people should have confidence to mine with F2pool and no shady actions will occur?

There is no impact on miners at all, and our PPS fee is very low if you consider all those merged coins we are giving out: 7 NMC/IXC/I0C is about 0.019 BTC or 1.9% of your earning. The loss is also trivial to us. Our Bitcoin reserve is more than 10000 BTC and we also have many altcoins.

I do mine with F2pool at times, currently as a backup, and I think we deserve to hear more about how this does not impact us.
Care to comment on 'SPV mining' explanations being provided by the bitcoin folks?
The short version is they state you and antpool caused most of this because you were not validating blocks.

Do you have a response, or is this the way you plan to run your pool in the future?

We will continue do SPV mining despite the incident, and I think so will AntPool and BTC China. We will do it more carefully in the future however. Today's incident was caused by one of AntPool's outdated bitcoinds. BTC China and us simply followed AntPool's block announcement, only they have worse luck, so they did not generate as many blocks as us.

We will continue do SPV mining despite the incident, and I think so will AntPool and BTC China.

Another very good reason people should not mine on Chinese pools.  This is EXTREMELY bad for the Bitcoin network.

[JorgeStolfi]

They were cheating the system. Bitcoin has one variable that can't be predicted - human behavior. The system will always be flawed as long as someone sees an advantage in doing the wrong thing. Bitcoin isn't a worldwide corporation but it's players must act as if it were. Independent global actors must each do their part correctly and for the good of the whole except all of them are motivated differently. The problem with a system controlled by no one and everyone is the old adage, what's best for me is what's best.

Sorry, that was not the idea.  Players were supposed to behave in certain ways because of the economic incentives built into the protocol, not because of "the good of the whole".   If players find that it is more advantageous to them to behave in ways that are bad for the system, that is a flaw of the protocol, not a fault of the players.