Exploring the Theoretical Side of Double Spending Bitcoin

Let’s get into how theoretically someone could double spend Bitcoin. This is more about game theory and how it jives with mining strategies.

First off, if a transaction is confirmed and in the longest chain, mining the next blocks doesn’t invalidate it. It just gets pushed down further. Those unconfirmed transactions chill in mempool, not on the chain.

Right, but if you’re mining those blocks, there’s zero incentive for other miners to join you in that double spend. A one-time huge fee isn’t likely to motivate them to build a stronger chain.

Exactly, if miners see a conflicting transaction, they’ll reject it. Even if someone tries to pull a 51% attack, it’s super costly and not worth it for most mining pools. They’d rather stay honest.

By the way, this probably belongs in the tech section, not economics. Just saying.

I think you’re missing the point here. If transaction A is in the blockchain already, it complicates any attempt to double spend it.

Manipulating the chain gets tougher the deeper you go. It’s almost impossible to pull off with over 10 confirmations.

Testing this on testnet is a good idea. I successfully sent a massive fee once, and no one reorged my block. Curious how much you can push without reorgs.

Once miners see a confirmed transaction, they’ll reject any attempts at a second one. You can’t just broadcast a conflicting transaction and expect it to fly.

I’m guessing OP meant double spending after a confirmation. To pull that off requires the same miner to hit the next block, and they’d need to be in on the plan.

You could use "invalidateblock" but that’s easier said than done. Mining two in a row is a challenge.

Convincing a private miner might be simpler than trying with a public pool. As soon as suspicion hits, hash power will switch pools, making it harder.

For it to make sense economically, the amount needs to be huge. No one’s accepting big transactions with just one confirmation.

Sure, your attack could be foiled by waiting for confirmations, but you’re right that if the miner thinks they’ll get a fat fee for a reorg, they might try it.

What if a miner attempts to double spend but can’t get a longer chain fast enough? That’s a real concern.

I read you can cancel a transaction with one confirmation using certain services. Is that legit? Seems sketchy for miners to help a double spend.

Seems unlikely, but you can track past block activity. If something shady happened, we’d have seen some block hash at those points.