How to do Double spend

[Kakmakr]

Now that you have a basic understanding of a double spend, you should consider the consequences of such an attack. Let's say you successfully execute a double spend, it would quickly get noticed and people will hear about this. The direct result of that would be that massive amounts of people will start dumping their coins, because the whole concept of "security" would be destroyed.

The demand for coins will dissapear and there will be a over supply of coins on exchanges .....the next thing you know, the price will go down to almost $0. So the attacker will never be able to do this again and the remaining coins they have will be worthless.

Never kill the Cow for it's meat, because you will lose the daily milk.     

[bitbunnny]

Now that you have a basic understanding of a double spend, you should consider the consequences of such an attack. Let's say you successfully execute a double spend, it would quickly get noticed and people will hear about this. The direct result of that would be that massive amounts of people will start dumping their coins, because the whole concept of "security" would be destroyed.

The demand for coins will dissapear and there will be a over supply of coins on exchanges .....the next thing you know, the price will go down to almost $0. So the attacker will never be able to do this again and the remaining coins they have will be worthless.

Never kill the Cow for it's meat, because you will lose the daily milk.     

Well, I don't think that he would actually succeed to make it in practice, I don't believe double spend is actually possible. And even if he did, that wouldn't have such deep impact like you describe, loss of confidence, price drop and everything. This is a little bit exaggerated.

[BitHodler]

Well, I don't think that he would actually succeed to make it in practice, I don't believe double spend is actually possible. And even if he did, that wouldn't have such deep impact like you describe, loss of confidence, price drop and everything. This is a little bit exaggerated.

Double spending is quite easy if you know how to do it. I have done it once (before RBF was a thing) in order to actually have the coins I sent to my exchange account confirm, which otherwise might have taken a day or so.

Scammers have double spent on ATMs and noobs they "sell" Bitcoin to. Noobs see the Bitcoin show up in their wallet and think it's all right, not knowing that they don't have these coins until the transaction confirms.

And yes, this is actually a pretty common occurrence. It doesn't require you to "break" the network and therefore no one will panic sell. Safest option is to always wait for that 1 confirmation when transacting with someone you never met.

[figmentofmyass]

Funny, how many of the same users tout how bitcoin is so secure, but are skittish of explaining how to doublespend on BTC.

Option 1:
1st , you have to find someone dumb enough to accept zero confirmations

bitcoin's entire security model against double spending depends on mining confirmations. only a total noob (or someone malicious) would tout zero-confirmation transactions as secure.

Option 2:
Coerce the 4 top bitcoin pool operators

how would you pull that one off?

[Khaos77]

Funny, how many of the same users tout how bitcoin is so secure, but are skittish of explaining how to doublespend on BTC.

Option 1:
1st , you have to find someone dumb enough to accept zero confirmations

bitcoin's entire security model against double spending depends on mining confirmations. only a total noob (or someone malicious) would tout zero-confirmation transactions as secure.

Option 2:
Coerce the 4 top bitcoin pool operators

how would you pull that one off?

If you don't know that , the second I said [coerce],
You're too naive and would be too traumatized if I went into detail.
   

[kaya11]

I like how you say, "educational purposes"

Why not search it in Google and use the researches that are there in your results? I think it's easy to do that but I hope you share what you are planning to do or put out the "educational purpose" you are talking about. Lol.

Maybe he can't understand it just by reading, sometimes people needs live demo to understand it very well, including me, as he  said  he needs a live demo  above. This guy is taking up our time.

[nc50lc]

Funny, how many of the same users tout how bitcoin is so secure, but are skittish of explaining how to doublespend on BTC.

Option 1:
1st , you have to find someone dumb enough to accept zero confirmations

bitcoin's entire security model against double spending depends on mining confirmations. only a total noob (or someone malicious) would tout zero-confirmation transactions as secure.

The main issue on his post is most nodes will reject the second unconfirmed transaction due to the second attempt to spend the first TX's UTXO.
Nodes are designed to reject those by default and there's a very high chance that it will not reach a miner's node.

...unless it's labeled: RBF which is disabled by default <-(I haven't tested yet).

I believe by principle, if you try that, the double-spending attempt will be considered both canceled transactions.

If ever there are two transactions that are trying to spend the same UTXO was accepted by a mining node, one of them will eventually get a confirmation and one will be discarded.
The only exception is: if both of them have too little fee to get a confirmation within (default) two-weeks time, both will be rejected.

[bob123]

There are multiple approaches to double spend a transaction.

• Relay the original TX to the victim while relaying the double-spending TX to the rest of the network
• Start a race attack by 'separating' the network
• Cooperate with a miner
• RBF

But based on your actual knowledge regarding bitcoin, i heavily doubt that it is for 'educational purpose'.

Fortunately you won't be able to make use of it outside of a testing environment.

If ever there are two transactions that are trying to spend the same UTXO was accepted by a mining node, one of them will eventually get a confirmation and one will be discarded.
The only exception is: if both of them have too little fee to get a confirmation within (default) two-weeks time, both will be rejected.

Just because they will be dropped from the mempool, this doesn't mean that it got rejected.
Actually, only one transaction should (if following the protocol specification) be allowed to enter the mempool. The first one. The second one should get rejected.