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Author Topic: bitcoin-jackpot.org a simple fair lottery  (Read 2092 times)
Sandra_Johns
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June 08, 2015, 10:00:03 PM
 #1

http://www.bitcoin-jackpot.org is a simple fair lottery.

Many people make a stake. One get the pot.

The chance to get the pot is the ratio between stake and Pot.

Example: Pod 10mBTC, Bet 1mBTC the chance is 10% to win the Pot

Any Player get 1% from cash tray back when playout, to control the system works correct.

No Registration is needed.

The minimal game time is one hour but nobody must call the playout.
So its possible the game run several days to increase the jackpot.

http://www.bitcoin-lottery.org/screenshot_bitcoin-Jackpot.jpg
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tspacepilot
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June 09, 2015, 03:14:32 AM
 #2

Looks fun, looks simple and transparent.  I was surprised to see that it seems like you've already got quite a good handful of users.  One question which isn't clear at first glance: how do you prove that the chance to win really was equal to the percentage of a person's bet to the pot.  That is, I can see all the relevant bets, but how can we know you distributed the odds fairly when you picked a winner?
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June 09, 2015, 03:46:03 AM
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Looks fun, looks simple and transparent.  I was surprised to see that it seems like you've already got quite a good handful of users.  One question which isn't clear at first glance: how do you prove that the chance to win really was equal to the percentage of a person's bet to the pot.  That is, I can see all the relevant bets, but how can we know you distributed the odds fairly when you picked a winner?

id like to know as well; provably fair would work either because there are multiple users in the lottery, I can see a lot of potential holes in the fairness of this lottery.

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June 09, 2015, 04:21:19 AM
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Looks fun, looks simple and transparent.  I was surprised to see that it seems like you've already got quite a good handful of users.  One question which isn't clear at first glance: how do you prove that the chance to win really was equal to the percentage of a person's bet to the pot.  That is, I can see all the relevant bets, but how can we know you distributed the odds fairly when you picked a winner?

id like to know as well; provably fair would work either because there are multiple users in the lottery, I can see a lot of potential holes in the fairness of this lottery.

If he can find a clever way to prove it, that would certainly change the scene around here--a new type of provable fair game.  If he can't prove it, I'd be skeptical because the house could be playing with the odds.  Since we don't know who owns what bitcoin address, we don't know that the house doesn't own the winning address either.  Not saying they are cheating, just that it's pretty crucial to prove they aren't in this setup (IMO).
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June 09, 2015, 04:33:13 AM
 #5

Looks fun, looks simple and transparent.  I was surprised to see that it seems like you've already got quite a good handful of users.  One question which isn't clear at first glance: how do you prove that the chance to win really was equal to the percentage of a person's bet to the pot.  That is, I can see all the relevant bets, but how can we know you distributed the odds fairly when you picked a winner?

id like to know as well; provably fair would work either because there are multiple users in the lottery, I can see a lot of potential holes in the fairness of this lottery.

If he can find a clever way to prove it, that would certainly change the scene around here--a new type of provable fair game.  If he can't prove it, I'd be skeptical because the house could be playing with the odds.  Since we don't know who owns what bitcoin address, we don't know that the house doesn't own the winning address either.  Not saying they are cheating, just that it's pretty crucial to prove they aren't in this setup (IMO).

no youre right, it is absolutely crucial to prove its fairness, as for something creative, maybe it could use the current provably fair system and take X number of random characters from each deposit address, and the turn that into the "client seed," just some random thought im playing with.

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June 09, 2015, 05:30:02 AM
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Looks fun, looks simple and transparent.  I was surprised to see that it seems like you've already got quite a good handful of users.  One question which isn't clear at first glance: how do you prove that the chance to win really was equal to the percentage of a person's bet to the pot.  That is, I can see all the relevant bets, but how can we know you distributed the odds fairly when you picked a winner?

id like to know as well; provably fair would work either because there are multiple users in the lottery, I can see a lot of potential holes in the fairness of this lottery.

If he can find a clever way to prove it, that would certainly change the scene around here--a new type of provable fair game.  If he can't prove it, I'd be skeptical because the house could be playing with the odds.  Since we don't know who owns what bitcoin address, we don't know that the house doesn't own the winning address either.  Not saying they are cheating, just that it's pretty crucial to prove they aren't in this setup (IMO).

no youre right, it is absolutely crucial to prove its fairness, as for something creative, maybe it could use the current provably fair system and take X number of random characters from each deposit address, and the turn that into the "client seed," just some random thought im playing with.

Indeed, I'm not a mathematician, but I think it's pretty doable---lets say you put an array of the number of players weighted by probability mass for each player to win (so if there are two players at 25%, 75% odds, you'd have (1,2,2,2) for player 1 and player 2, respectively). Then you need to pick an array element based on a provably fair random number.  And that part should just be a matter of seeds from each player and a seed from the server (hashed and distributed, of course).  The thing is that each player needs access to all the player seeds to verify the game, so you'd have to make that part transparent.

Looking forward to OPs reply here.
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June 09, 2015, 06:06:56 AM
 #7

I was surprised to see that it seems like you've already got quite a good handful of users.
This is actually a red warning IMHO Tongue

Then you need to pick an array element based on a provably fair random number.  And that part should just be a matter of seeds from each player and a seed from the server (hashed and distributed, of course).  The thing is that each player needs access to all the player seeds to verify the game, so you'd have to make that part transparent.
The last player (seed) would be the crucial variable in the calculation since any change on the total seed combination changes the result. Basically if the last player is fake and actually the site owner, he can still make any result he wants.



Anyway, I am not sure what I am seeing and what the concept of this gambling site is. Really no idea how it works and your site looks terrible (and some bad typos like "pod" instead of "pot".) You should make it more clear how your game works and how it is exactly fair (provably fair is the only type of fair that we know here.) GL.

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June 09, 2015, 06:07:17 PM
Last edit: June 09, 2015, 09:19:12 PM by Sandra_Johns
 #8

Hello, I can explain the mathematician,

Example:

Player 1: 1,0 mbtc
Player 2: 5,0 mbtc
Player 3: 10,0 mbtc

together: 16 mbtc

now create a random number between 0 and 16

0-1 Player 1 win
1-6 Player 2 win
6-16 Player 3 win

Thats absolutly correct simple way to realize the different chances.



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June 09, 2015, 06:19:02 PM
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Actually it looks pretty easy to make provably fair. For each round, have an address which all bets go to. Each round should end at a certain block #number.

At the block #, count how many satoshis were received at to the round address. Then define n to be: (block_hash % amount_of_satoshis_sent) + 1. Now who ever sent the nth satoshi to the address (as defined by blockchain-order) is the winner. The prize pool gets sent back to the sending address.

For people who use a shared-wallet, you could build a forwarding-service without complicating the provably-fair system.

Potential attacks against this scheme would be a miner using block-discarding, however as shown in another thread somewhere it would be mind-boggling expensive. Unless the prize pool has thousands of bitcoins, it's not worth worrying about
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June 09, 2015, 09:16:11 PM
 #10

Hello, I can explain the mathematician,

Example:

Player 1: 1,0 mbtc
Player 2: 5,0 mbtc
Player 1: 10,0 mbtc

together: 16 mbtc

now create a random number between 0 and 16

0-1 Player 1 win
1-6 Player 2 win
6-16 Player 3 win

Thats absolutly correct simple way to realize the different chances.

Sandra_Johns, that's indeed a correct way to distribute the probability.  However, we'd like you to be able to prove the part I bolded: that the number is actually random.

@RHavar, that seems clever, modding by the amount of satoshis means that you distribute the probability according to buyin---nice!

@Sandra_Johns, see @RHavar's solution please!

Sandra_Johns
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June 09, 2015, 09:48:34 PM
 #11

I have commit your questions and ideas into the script.
Now the php-script for the playout is readable for any user.
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June 09, 2015, 09:56:44 PM
 #12

I haven't tested this site yet, so I don't know if it is userfriendly or not.

If there is one thing I am sure about, it's that the layout isn't really appealing to me. A better layout would attract more customers.

Where to gamble with your BTC? | BitcoinCasinoSource.info     Website      and       thread 
Sandra_Johns
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June 09, 2015, 10:49:47 PM
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Oh yes, Layout is  my greatest weakness.
The Layout is terrible.
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June 09, 2015, 11:03:53 PM
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I have commit your questions and ideas into the script.
Now the php-script for the playout is readable for any user.

As dooglus has said in other threads, even publishing source code isn't a guarantee that the same binary compiled from that code is what's running on a particular server.  I'd reconsider making your site provably fair, just showing this source doesn't acheive that.

One major issue is that we can't know which deposits are from the house.

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June 17, 2015, 03:03:01 PM
 #15

The script is more transparent now.
deposits from server are indicating now.
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June 17, 2015, 03:27:19 PM
 #16

The script is more transparent now.
deposits from server are indicating now.

While it seems like a step in the right direction, I think you're still not getting what people above were saying about how this needs to be provably fair.  If you implement it in a provably fair fashion (see what RHavar said above), you might actually get a lot of players.  Until then, people are going to be skeptical.

One other feedback, although it's less important than the provably fair aspect, the numbers don't seem to add up (at first glance).  For example, I see a deposit of 10mBTC and a payout of around 100mBTC but then the payout percent column says 1000%?!  But 10 is 10% of 100, not 1000%, seems like you're missing a decimal point somewhere.  Also, looking on the blockchain for that address:

https://blockchain.info/address/1ELLXu1nBLZQooJmHfsrW2XHoeKKmA9QwV

I don't see any payout of 100mBTC.  So I must be misunderstanding something quite a bit.
Sandra_Johns
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June 17, 2015, 06:05:54 PM
 #17

https://blockchain.info/address/1ELLXu1nBLZQooJmHfsrW2XHoeKKmA9QwV is the incomming address (10mbtc)
https://blockchain.info/address/1ZCcpTUwrJPuz5pCtit1aNEiXY4o9t7wK is the outgoing address (105mbtc)

after the playout blockchain need some minutes to show the transactions

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June 17, 2015, 06:13:42 PM
 #18

INOUTPercent
1010100%
1011110%
1020200%
101001000%

I make a mistake?
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June 17, 2015, 08:29:34 PM
 #19

https://blockchain.info/address/1ELLXu1nBLZQooJmHfsrW2XHoeKKmA9QwV is the incomming address (10mbtc)
https://blockchain.info/address/1ZCcpTUwrJPuz5pCtit1aNEiXY4o9t7wK is the outgoing address (105mbtc)

after the playout blockchain need some minutes to show the transactions

Yes, I see this now.

INOUTPercent
1010100%
1011110%
1020200%
101001000%

I make a mistake?

I can't tell what it's supposed to mean.  Normally "percent" means by 100 (literally "per"->by;"cent"->100) .  So a percent usually has two numbers n,m and expresses their ratio with the denominator of 100 rather than m.  For example, to find a percent for n,m is to solve for p where: n/m = p/100.

So in your table, what are the things you are comparing.  The best guess I have is that you are referring to some kind of multiplier.  So maybe you're saying that if you bet 10 and win 100 that you got a 1000% multiplier of your bet?  But under that interpretation, the first row sucks,  that guy only gets his bet back if he wins.  Who wants to bet 10 and "win" and get back the same 10.  If this is the interpretation you want, why don't you express the rightmost column as "multiplier" or something like that:

Bet  Win   Multiplier
10   10     x1
10   11     x1.1
10   20     x2
10   100   x10

I think that's a lot clearer to say x10 than 1000%.  And I still don't get why that last bet got a x10 multiplier when the others got x1, x1.1, x2.  I guess my point is that this is very confusing.

Also, I'm starting to think there's some (nefarious) reason why you're not interested in making this provably fair.
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June 18, 2015, 02:14:52 AM
 #20

I have changed the rate form percent to Multiplier.
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