Quote from: Zhor on June 24, 2017, 03:18:09 PM

Quote from: Myfe on June 24, 2017, 02:55:27 AM

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i think you meant weekend.

Quote from: wetsuit on June 24, 2017, 02:08:43 PM

Sorry about the delay with this, I have just gone through all the lottery drawing ideas and this is the best one I found mainly because I don't have to store 200 million+ ticket numbers for each round and the "window" system for picking winners is what I already use.

I have a few modifications to this idea though to make it easier to verify and implement. So, this is how the lottery will work with my modifications:

1) Before a lottery round starts, a server seed will be generated and it's hash will be provided.
2) After a lottery round is concluded, a list of user id's and tickets will be produced in a text file ordered by ascending user id's. This order will be used to create the "ticket-windows" as Zhor and edge777 have described below.
3) Then a tweet will be made to our twitter account containing the following:

A future bitcoin block number that has not yet been mined. The block hash of this block will be used as the client seed. This block will be at least 3 blocks in the future.
The link to the text file in 2.
A MD5 hash of the text file in 2 to verify that the contents of the text file have not been modified since posting. If the contents of the file change, it will produce a different MD5 hash which will not match the one provided originally.

Twitter is ideal for this because it will provide a timestamp that can be verified to check that the block number provided is in the future. Also, tweets cannot be edited, only deleted so if I delete the original tweet and post a new one after the block has been mined, it will have a timestamp greater than the timestamp of the block used for the client seed.

4) The server seed, block hash and an incrementing nonce will be used to draw the 10 lottery winners.

Please let me know if this can be exploited in any way or if it needs clarification. I believe this is the easiest implementation that can also be verified quickly by users. I am still open to ideas until I proceed with implementing this (in the next few weeks) so please post your ideas and if something better comes along, I'll use that. If not, the reward will be divided equally between edge77 and Zhor.

The original idea is below.

Quote from: Zhor on June 15, 2017, 09:12:02 PM

well, hello everybody from bitcointalk,
[...]

hey, nice to see that you liked my idea!
I still don't like the usage of 3rd parties, but at least it will hopefully bring more people to your twitter page. Let's just assume that it is impossible to bribe twitter to change a tweet.
I like how it is much easier to verify, but it is on the cost of privacy. Over the weeks, everyone can analyze the "basic activity" (seen as the amount of tickets a user spent on the lottery) of individual users and of the system as a whole. Also - and this could hurt more - you will publish indirectly the number of inactive users. And you can also see how long it takes for any user (in special or in general) to go inactive.
However i dont see any way to manipulate the system as user or admin.

You also need to publish the exact algorithm how the 10 lottery winners are calculated.

I don't think it will be a breach of privacy since it will just be a list of user id's and their tickets for that week. Other people knowing the number of active and inactive users will also not be a problem for us.