Bitcoin Forum

Bitcoin => Development & Technical Discussion => Topic started by: maxvon on February 23, 2014, 06:46:25 PM



Title: Provably fair unknown event time for Bitcoin gambling
Post by: maxvon on February 23, 2014, 06:46:25 PM

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.


Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: THOUROUGH on February 23, 2014, 08:35:19 PM

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...:-)


Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: jimhsu on February 23, 2014, 11:42:21 PM
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)


Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: Shahrukh on February 24, 2014, 01:08:10 PM
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 ?


Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: wheatstone on February 24, 2014, 09:34:24 PM
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.



Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: Ricke on February 24, 2014, 09:59:47 PM
You could draw a winner as soon as the newest Bitcoin block hash contains a certain sequence.


Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: roslinpl on February 24, 2014, 10:23:33 PM
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!


Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: deepceleron on February 25, 2014, 09:47:57 AM
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.


Title: Re: Provably fair unknown event time for Bitcoin gambling
Post by: deepceleron on February 25, 2014, 10:02:17 AM
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.