Re:Proof-Of-Work is a Decentralized Clock
by discussedbefore on Tuesday April 17, 2018 @07:15PM
(#16863138)
> increase the fee of a transaction after the fact
Someone should have volunteered to help the Pineapple Fund do this instead of switching to Bitcoin Cash (or maybe this is what "Child-Pays-For-Parent" is, and it cost too much). https://news.ycombinator.com/item?id=15995391
>> Since this created a series of unconfirmed transactions, we had to do something drastic: use Child-Pays-For-Parent with a very significant fee.
> maybe this is what "Child-Pays-For-Parent" is
Yep, this is what that means. The downside is that the 'child' transaction doesn't just pay for the 'parent' transaction, but also for the 'child' transaction itself. If you make the child transaction a really complex one that draws from many parents, that transaction becomes larger (in terms of bytes) and thus becomes more expensive.
You can use this to increase the fee of a transaction after the fact. So, suppose A has a fee of 0.001 in the first transaction, and the current fee needs to be 0.01 . Then, B has this transaction, but no-one will put it into a block, so B hasn't really received his money yet. A could sign another transaction with a higher fee that would send the money back to A. This could happen until the original transaction was actually deep enough in the chain.
But using your situation, B can do the same thing as A. B can create a transaction sending his own 0.999 BTC to another address of his, and include a fee here of 0.019 . In this fee, there is 0.01 to fund this transaction, and another 0.009 to fund the fee A forgot to include. Miners will see this, and include both transactions, and B is guaranteed he has his money.