Doublespend on longest chain? | Bitcointalksearch.org

PhoenixZephyrus

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I have no idea why this was even considered newsworthy?! It has happened probably numerous times in the past before, and this seemed like a way to reduce the trust of the general public in bitcoin, riding on its volatility and turning it over by a huge amount within a week. This kind of FUD paved the way for headlines like these :

Quote

Bitcoin heads for worst weekly loss in months

https://www.gadgetsnow.com/tech-news/bitcoin-heads-for-worst-weekly-loss-in-months/articleshow/80404657.cms

News in a lot of countries, and bitcoin media in general have further promoted this fall as bitcoin being in a bubble (seriously how is this stuff still ongoing?!) and TV news have shown the subsequent fall in price as "further proof that bitcoin isn't a real currency" and it being "just a speculation bubble" for investors.

In reality, this wasn't anything major at all, just a block reorganization of the longest chain winning out in the long run, but BitMEX research was probably using words that they thought would grasp a lot of attention, which, if nothing else, confused a lot of people who haven't been following bitcoin, and didn't know about block reorganization, and it even caused a few people to sell-off.

thecodebear

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Quote from: OgNasty on January 21, 2021, 03:19:19 PM

Seems like everything worked as it should. I don’t think this is the cause for the recent drop and the media is just not used to Bitcoin’s volatility while grasping at answers. I imagine this next year will be full of all sorts of ridiculousness from news outlets desperate to have a beat on Bitcoin.

Yeah Bitcoin worked exactly as it is supposed to. But this absolutely 100% is the reason for the drop. The drop started immediately after this lie about a double spend started hitting the internet. The only question is how damaging this lie will be to the price in the short term. Price looked like it was coming back up after the initial double spend panic sell, bouncing back over $32500 but has since dumped again back to $30k.

Either some of the market still hasn't realized the double spend was a lie, or people are simply now just reacting to the dump through support levels at $33k/$34k caused by the double spend "news" so we are seeing more dumping just because people are panicking at the price dropping. What a shame. Price is now going after the $30k support level. Would be a shame if we break back down under $30k and this correction is extended all just because a false story was spread on the internet, when there was likely no way Bitcoin would have ever even visited $30k again otherwise. Also shows how immature the Bitcoin market still is when such an obviously false story can lead to a dump through support levels. Hopefully $30k will hold today and the market gets the news that there was no double spend and people stop selling based off a lie!

OgNasty

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Seems like everything worked as it should. I don’t think this is the cause for the recent drop and the media is just not used to Bitcoin’s volatility while grasping at answers. I imagine this next year will be full of all sorts of ridiculousness from news outlets desperate to have a beat on Bitcoin.

NotFuzzyWarm

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Quote from: ?? on ??

I thought cointelegraph was a reliable source, now I know for the future

A reliable source? ROFL!
They and most other crypto news sites on the web pretty much just immediately post any 'news' sent to them by contributors without any sort of editorial checks for accuracy. Sometimes like in this case - the author was pretty clueless about what happened... Then there is the issue of pay-to-print where PR firms literally pay the sites to carry 'news' announcements of some new service/product/etc. Again, rarely any checks for accuracy Roll Eyes

I use such sites only as a very general heads-up on what is happening in the crypto space. If I see something interesting I then always dig into the source of the news to get the complete story - not just cherry-picked tidbits that attract eyballs. In short - always take their 'news' with a grain of salt.

bitmover

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Quote from: fillippone on January 21, 2021, 01:12:06 PM

Said in my comment above the LOWER FEES transaction was confirmed, AND this transaction appeared AFTER the one with higher fees.
So definitely not a standard RBF transaction. Like the sender “colluded” with the miner to have this second lower transaction in the block.

Before or after makes no difference, the block height of both transactions were the same.

Nobody knows who the next miner will be, there are about 20-30 pools mining blocks everyday.

The miner who mined the next block received the chain (with a transaction that paid less) first. That previous transaction made no difference for him. But that chain was broadcasted first to him and for him it was always the longest chain. He ignored the other one.

Every milisecond counts. Transactions are valid, they just move on.

pawanjain

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Quote from: bitmover on January 21, 2021, 10:20:05 AM

No. No double spend happened.

Cointelegraph is asking opinion about BSV and BCH scammers.

This is a very common situation, which was specified in the whitepaper 12 years ago.

Two miners mined a block at the same time with different transactions, and a RBF uin one of them.

After a few blocks this situation will be normalized, as predicted in the whitepaper. This is very common, and COINTELEGRAPH is spreading FUD to get clicks.

This is why exchanges asks for a 6 block confirmation before accepting your transation.

https://twitter.com/aantonop/status/1352250328960229377

This is exactly what am telling people whom I know that they shouldn't panic so much. It just happened out of a coincidence and the bitcoin protocol remains intact.
As soon as the next block was mined the previous block on the second chain became stale and thus the longest chain was still secure with no double spends.
FUD is spread in the Social media but I take it as a good thing since bitcoin price dumped good giving opportunities for others to dive in at this price Grin

Am just telling everyone I know to buy bitcoin at this price as a good opportunity has arrive to stock in some BTC

P.S : Boycott Cointelegraph

Mr_Akbar

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Quote from: fillippone on January 21, 2021, 01:12:06 PM

The only thing that does not add up is, as I said in my comment above the LOWER FEES transaction was confirmed, AND this transaction appeared AFTER the one with higher fees.
So definitely not a standard RBF transaction. Like the sender “colluded” with the miner to have this second lower transaction in the block.

This is the bit that seems so suspect to me...

But I'm thankful that it's not a blatant double spend at least.

fillippone

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Quote from: bitmover on January 21, 2021, 12:33:40 PM

Quote from: fillippone on January 21, 2021, 11:09:31 AM

As I said, the mined fee has a lower, not higher fee. So this is very strange to me.

This is not strange.

RBF is, in simple terms, a second transaction that you will send with a higher fee to get a faster confirmation.

His first transactions with lower fee was not confirmed, so he sent a RBF.
But both of those transactions were confirmed at the same height, in different chains.
<...>

The only thing that does not add up is, as I said in my comment above the LOWER FEES transaction was confirmed, AND this transaction appeared AFTER the one with higher fees.
So definitely not a standard RBF transaction. Like the sender “colluded” with the miner to have this second lower transaction in the block.

thecodebear

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Quote from: bitmover on January 21, 2021, 12:33:40 PM

Quote from: fillippone on January 21, 2021, 11:09:31 AM

As I said, the mined fee has a lower, not higher fee. So this is very strange to me.

This is not strange.

RBF is, in simple terms, a second transaction that you will send with a higher fee to get a faster confirmation.

His first transactions with lower fee was not confirmed, so he sent a RBF.
But both of those transactions were confirmed at the same height, in different chains.

Miner A mined the RBF and miner B mined the lowest one (maybe the RBF tx was not broadcasted to him yet when he mined) at THE SAME TIME! It is a coincidence, and the longest chain will survive.
Both chains are valid now.

In the end the chain mined by miner B was the longest chain. Miner A lost his block reward, his chain is not valid anymore and all transcitons in his block are not valid (but most of them were mined by miner B at the valid chain).

So the RBF is not valid anymore, because you cannot doouble spend an already spent coin. there is no RBF of that transaction in the longest blockchain now.

Yeah exactly. There was no double spend. Just a normal event for a blockchain. The article(s) that are saying there was a double spend are spreading FUD, and unfortunately panic sellers in the market reacted as they do and dumped the market. Once the market realizes this wasn't true I would assume we'll see a quick rebound. Market just went back down $1000 so I guess the market hasn't realized whats going on yet haha.

bitmover

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Quote from: fillippone on January 21, 2021, 11:09:31 AM

As I said, the mined fee has a lower, not higher fee. So this is very strange to me.

This is not strange.

RBF is, in simple terms, a second transaction that you will send with a higher fee to get a faster confirmation.

His first transactions with lower fee was not confirmed, so he sent a RBF.
But both of those transactions were confirmed at the same height, in different chains.

Miner A mined the RBF and miner B mined the lowest one (maybe the RBF tx was not broadcasted to him yet when he mined) at THE SAME TIME! It is a coincidence, and the longest chain will survive.
Both chains are valid now.

In the end the chain mined by miner B was the longest chain. Miner A lost his block reward, his chain is not valid anymore and all transcitons in his block are not valid (but most of them were mined by miner B at the valid chain).

So the RBF is not valid anymore, because you cannot doouble spend an already spent coin. there is no RBF of that transaction in the longest blockchain now.

fillippone

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Quote from: ranochigo on January 21, 2021, 10:52:43 AM

Quote from: fillippone on January 21, 2021, 10:44:37 AM

What is the difference in the two transactions?

I linked it with my post.

You were too fast for me!

Quote from: ranochigo on January 21, 2021, 10:52:43 AM

Quote from: fillippone on January 21, 2021, 10:44:37 AM

The fees? (after an initial claim of an RBF transaction being bumped up, it appears the was not the case)

One of the transaction actually do have a higher fee and that makes me think that the transaction that was on the losing block was actually the RBF'ed transaction, since the lower fee transaction actually signals optin RBF.

Following the explorer links, looks like the transaction with with higher fees, and that was NOT included was submitted BEFORE the transaction that was included in the block, with a lower fee. Looks like the sender passed the lower fee transaction directly to the miner, so that to be included in the block. Otherwise the mempool manager of teh miner would have included this later, lower fee bearing transaction on their block.

Quote from: ranochigo on January 21, 2021, 10:52:43 AM

Quote from: fillippone on January 21, 2021, 10:44:37 AM

I guess this was intentional.

No. Both pools mined the transactions within seconds apart, and it's likely that SlushPool didn't manage to replace the existing transaction with the RBF transaction that spends a higher fee. Unless the attacker owns either of the pool, it's highly unlikely that it was planned at all.

As I said, the mined fee has a lower, not higher fee. So this is very strange to me.

ranochigo

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Quote from: fillippone on January 21, 2021, 10:44:37 AM

A single UTXO double spend on two chains is possible.
Is this the case?

Correct.

Quote from: fillippone on January 21, 2021, 10:44:37 AM

What is the difference in the two transactions?

I linked it with my post.

Quote from: fillippone on January 21, 2021, 10:44:37 AM

The fees? (after an initial claim of an RBF transaction being bumped up, it appears the was not the case)

One of the transaction actually do have a higher fee and that makes me think that the transaction that was on the losing block was actually the RBF'ed transaction, since the lower fee transaction actually signals optin RBF.

Quote from: fillippone on January 21, 2021, 10:44:37 AM

The recipient address? Well, this would technically be a double-spend. But is this what happened?

The transaction had an additional output that was spent to a P2SH address and a few different UTXOs being spent as well.

Quote from: fillippone on January 21, 2021, 10:44:37 AM

I guess this was intentional.

No. Both pools mined the transactions within seconds apart, and it's likely that SlushPool didn't manage to replace the existing transaction with the RBF transaction that spends a higher fee. Unless the attacker owns either of the pool, it's highly unlikely that it was planned at all.

webtricks

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Just because a stupid Exchange wanna stand out in the competition and credit the deposits after only 1 confirmation, it doesn't mean Bitcoin is supposed to work that way. This is an unnecessary FUD spread by Bitmex. Such events happen and there is nothing to worry if parties accept the transactions after more than 1 confirmation (3-6 preferred).

Added @Cointelegraph website to my ignore list.

fillippone

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Sorry, I need a clarification on what happened.

A single UTXO spent twice on the same block it is clearly not possible. It is a not valid transaction, so it would be incredibly low possibility to happen.
A single UTXO double spend on two chains is possible.
Is this the case?
What is the difference in the two transactions?

The fees? (after an initial claim of an RBF transaction being bumped up, it appears the was not the case)
The recipient address? Well, this would technically be a double-spend. But is this what happened?

I guess this was intentional.
Please remember today is the day 21 of the first month of the 21 year of the 21 century, the dollar amount was roughly 21 USD...... who bet on the sender on the 21 minutes after 21 hour Time Zone?

ranochigo

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There's a discussion here: https://bitcointalksearch.org/topic/is-1-confirmation-enough-for-bitcoin-transactions-5311173

Let's get some facts right. Here's the replaced transaction: https://www.blockchain.com/btc/tx/a13c2bdefcd51ef2a162f232179676c848b853b11596ac3381b70726758cfd41 and the original transaction, which was confirmed in the longest chain: https://www.blockchain.com/btc/tx/9e19bc72f3b9bb23351311f88dc6f5c2e7a209a4fb0ad80b35d50f765e343e29. In this case, both of the transactions were mined at the same height in different blocks and one of the blocks eventually prevailed to be the longest chain. Unlike what usually happens in normal circumstances, it appears to be the one with a much lower fee. This is something that is already known and is not a network weakness.

To prevent this from happening, the merchants should operate a well connected node to monitor for any possible forks and/or competing transactions on the blockchain and delay the provision of goods and/or services if that transaction is not included in both blocks. If it isn't, then the merchant has to wait for another confirmation for the transaction to be confirmed in the longest chain. Note that lengthy block reorgs are not common and I would expect 3 confirmations to be more than sufficient for larger amounts and 1 confirmation to still be safe in day to day use for smaller transactions provided that the above has been met.

Upgrade00

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There seems to be individuals pushing the double spend fud using the mainstream media inorder to scare holders to sell off cheap. A search for:

Code:

Bitcoin double-spend spotted in the wild

shows a series of coordinated publications by various news outlets spreading FUD.
Here's a detailed explanation from Andreas Antonopoulos on twitter - https://twitter.com/aantonop/status/1352258125932371968?s=19

TryNinja

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It's literally on the link you posted:

Quote

Multiple blocks were produced at height 666833. As new blocks are mined that reference one of these blocks as their parent, the heaviest chain survives and the other blocks become stale.

The longest chain won, as always. Wake me up when you find the same UTXO spent twice in the same block.

bitmover

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No. No double spend happened.

Cointelegraph is asking opinion about BSV and BCH scammers.

This is a very common situation, which was specified in the whitepaper 12 years ago.

Two miners mined a block at the same time with different transactions, and a RBF uin one of them.

After a few blocks this situation will be normalized, as predicted in the whitepaper. This is very common, and COINTELEGRAPH is spreading FUD to get clicks.

This is why exchanges asks for a 6 block confirmation before accepting your transation.

https://twitter.com/aantonop/status/1352250328960229377

Mr_Akbar

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Following this post... Trying to understand the significance of this occurrence.

I've done RBF transactions before when I've been too cheap on fees, but this is apparently not that?

LongTimeAgo

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https://forkmonitor.info/stale/btc/666833

Did a doublespend occur?

Topic: Doublespend on longest chain? (Read 270 times)