Can't we double spend on all 0-conf gambling games?

[n4ru]

https://satoshicircle.com/ doesn't require any confirmations as far as I'm aware. Isn't it possible then, to do a double spend if you lose by simply doing a no fee transaction and then doing a large fee transaction to your personal wallet if you were to lose your wager?

Am I missing something here? I know someone confirmed doing it with SatoshiDice long ago and it worked (https://bitcointalk.org/index.php?topic=130764.0). Did something change or is it still possible? If it is, wouldn't this be really bad for them?

[1715297368]

1715297368

[Mike Hearn]

Default miner code doesn't actually ever allow double spends. Indeed that's rather the whole point of Bitcoin. There is no such code that says "I saw a double spend with a higher fee so I'll take it", and it would be harmful if miners started doing that (it'd reduce the utility of the coins they earn too).

The double spend against SD was almost certainly possible because currently miners don't synchronise their memory pools with each other, so after initial broadcast some miners might forget about a transaction and then of course they'd accept a double spend. It'll get fixed at some point.

[Sukrim]

It might work if you could get a direct link to satoshicircle and several miners and they confirm VERY fast if you have won/lost. Fees don't really play a part in this.

Miners don't choose "better" double spends, they currently would probably reject them regardless of fees. It's not "forbidden" though, so it might be possible in the future if miners implement something like that. Not very likely though as long as a lot of bigger miners/pools are Bitcoin enthusiats and not only 100% looking for any possible profit in anything they could do.