I did not see a response from the devs to the above. It does seem within the realm of possibility that timestamp mismatches and reliance on an external data source could be exploited by sophisticated actors to tilt the odds in their favor, particularly by harnessing mining power. Is Chancecoin provably fair...for the house?
But to exploit this if I understand correctly, you must attack the whole Bitcoin network which is not worth it at all.
So it is just impossible.
I don't see why any of the major bitcoin mining pools couldn't do it.
Agreed. Particularly in light of phm's comment about the flexibility in timestamps:
Not sure if you know this, but timestamps in blockchain are prone to limited manipulation, rules of validating them are quite fuzzy. "A timestamp is accepted as valid if it is greater than the median timestamp of previous 11 blocks, and less than the network-adjusted time + 2 hours". So in fact nothing prevents miner from sending the block with timestamp few minutes in the past or in the future, timestamps in consecutive blocks don't have to always increase. How will you enforce such rule if you don't really know the real time when given block was mined?
Suppose quick draw lottery result N comes out at noon, and result N+1 comes out at 12:04:00. If, per notsoshifty's and phm's suggestion I can manage (as a major pool) to mine a block at 12:00:05 that includes a Chancecoin bet that I know will win if evaluated against result N, but include in that block a timestamp that is a bit before noon (maybe even well before noon, given phm's comments), how can the Chancecoin protocol absolutely ensure that my bet is evaluated against result N+1 or later?
I would only have have to sneak these "sure bets" into the blockchain once in a while to slowly drain the Chancecoin house dry.