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Topic: 5 BTC giveaway! (Ended) - page 6. (Read 6134 times)

sr. member
Activity: 293
Merit: 250
May 06, 2013, 05:01:49 PM
#1
Coinroll.it (Forum thread) is sponsoring a 5 BTC giveaway to lucky players.

All you have to do is play one game on our website - it can be as low as 0.00001 BTC. The amount of bets you make doesn't matter, and neither does the number that you rolled. What you need to do then is paste the bet ID of one of these bets as a reply to this thread.

The 3 winners will be chosen in 2 weeks using the following procedure:

We have chosen a random 12 digit hex ID in advance. The SHA256 hash of that string (plus extra padding to avoid brute forcing) is
Code:
f93e0d55b98e61dddfa4d3aae8204cfa727c909af15ef81ccdda9ac8313ceca4

The ID will be revealed in 2 weeks - the 21st of May.

The 3 winners are those with a bet ID which has the smallest modular distance to our random ID.


The modular distance is defined as
min((a - b) mod 248, (b - a) mod 248)
where a, b are 48bit integer representations of the hex IDs


Prize pool:
Winner: 3 BTC
2nd and 3rd: 1 BTC each

Winners will be asked to prove that they actually played the game by either signing a message from one of the originating addresses or performing an action on the website while logged in.


Why the modular distance? Why wouldn't a regular subtraction do?
If we used the absolute value of (a - b) instead then bets wouldn't have a uniform distribution of probability.

_______________________________________________________________

It's over!

The ID was e889acf0504e

The hashed message was
Code:
e889acf0504e_randompadding#gJ7n39u5

Script that was used

The output


Winners:
Pokerfan: 3 BTC
danieldaniel: 1 BTC
kuriboh: 1 BTC
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