Provably fair unknown event time for Bitcoin gambling

[maxvon]

I have a bitcoin lottery that is still in the prototype stage (bitsplit.it).

I believe that the game will be much more appealing, for certain reasons, if players (and the house) both don't know when the next winner will be chosen.

However, I am having a hard time with coming up with a (feasible) way to prove that the house doesn't know when the pot will split.

Any ideas are greatly appreciated.

[THOUROUGH]

I have a bitcoin lottery that is still in the prototype stage (bitsplit.it).

I believe that the game will be much more appealing, for certain reasons, if players (and the house) both don't know when the next winner will be chosen.

However, I am having a hard time with coming up with a (feasible) way to prove that the house doesn't know when the pot will split.

Any ideas are greatly appreciated.

live feed of the draw is the best i've come up with...:-)

[jimhsu]

Random.org offers JSON data that can be verified: https://api.random.org/verify

In beta until June 2014, when it'll no longer be free (apparently)

[Shahrukh]

You posted exactly same thread on bitcoin.stackexchange.com I am confused that you used word Provably in the title on both sites are you intentionally writing provably or its copy paste job ? or is there a word provably which I am not aware of ?

[wheatstone]

or is there a word provably which I am not aware of ?

"Provably" is the adverb form of provable, meaning something which can be proven.

[Ricke]

You could draw a winner as soon as the newest Bitcoin block hash contains a certain sequence.

[roslinpl]

You could draw a winner as soon as the newest Bitcoin block hash contains a certain sequence.

oh yes that would be nice


good luck with your project!


regards!

[deepceleron]

You could draw a winner as soon as the newest Bitcoin block hash contains a certain sequence.

That would be my thinking; however the blockchain doesn't provide a statistically constant rate of blocks, because mining isn't constant. If the goal is to generate on average one "event" per day or per week, it will still take manual intervention if the Bitcoin hashrate is increasing or decreasing, or above or below the difficulty; the actual hashrate cannot be determined to make it fair.

In addition, a criteria that may happen on average once per week (such as block hash mod 1008 = 0) has a not-insignificant chance of taking over a month, which may make players restless.

A better solution would be a satoshi-dice style provable, where the random choosing method for transactions sent into the jackpot pool is transaction hash plus site's secret which is pre-published as a hash. For example, if one in 16 bets may win the whole jackpot, etc... If I need to explain more, you shouldn't be running a gambling site.

[deepceleron]

A method I have just devised for a daily jackpot:

First block with UTC timestamp after specified time determines winner,
Users can supply or transaction ID generates their "random" number,
Lowest result of SHA256(block hash + user nonce) wins.

This still allows the house to cheat though, as they can enter their own drawing for free.