Is there any "provably fair" principle for lottery with more than one player?

[johny1976]

Hi,

the failure scenario with common provably fair mechanism:

1. Server generates a server seed and shows sha256-hash to all participants
2. Each gamer picks any amount of numbers from the list (say 1-100) and sets a client seed
3. Operator prepares to make the final bet (he can do it any time he want selecting all remaining numbers) by following:
3.1 He knows the sum of a client seeds of all participated players and also a server seed.. He does a simple calculation and abracadabra, he knows exactly what client seed to set to make one of his number the wining one.
3.2 He logs into (or creates) an account called "IAmNotTheOperator" to appear as a normal player
3.3 He sets a calculated client seed
4. Some ordinary gamer called IAmNotTheOperator makes a final bet
5. "IAmNotTheOperator won the game! Thank you and see you next time!"

so my question is:

When you operate a lottery-based casino game, what can you do to ensure your gamers that there's no way the op can cheat or impact the odds? Is there any way to do it?

Thank you

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[joschua011]

base the result on something that has not yet happend.

people can bet until some deadline is over, once over the result will be calculated.

lets say

result = hash( nytimes headline + DOW Jones index + bitcoin price + newest nicki minaj tweet + you get the idea... )

[johny1976]

base the result on something that has not yet happend.

people can bet until some deadline is over, once over the result will be calculated.

lets say

result = hash( nytimes headline + DOW Jones index + bitcoin price + newest nicki minaj tweet + you get the idea... )

I thought of something similar so you've kind of confirmed my hypothesis. Thank you :-)

[christinalorence]

I don't think that there is a probability like that. You can ask it to your seniors.

[midmir]

I am also interested in this subject.

You should check the cyberdice protocol.

I wonder how is implementable "the op or anyone can't leave with the money" scenario in case of autoexecutable public smart contract and 'public' private keys 

[Kprawn]

The owner of Freebitco.in is also looking for a solution to this... in this thread he explained how he is running his lottery on his site ---> https://bitcointalk.org/index.php?topic=319540.1180

In any scenario, a operator has to show what version of the code he/she is running at the moment when the winner is chosen. Some operators show a "Provably fair" code, but

there is no guarantee that they running that code, when they do the draw.  ....The person with the perfect solution to this, would make a lot of money, because this solution

is in high demand. 

[achow101]

You could have something where the lottery closes participation at a certain time and the drawing happens some time later and the server seed is based on something that happened after new entries were closed. Since the seed is determined after people can enter, the owner cannot enter with the right client seed since the server seed is unknown until the drawing.