Example: 50|1234567890
Deposit a minimum of 0.001 to 1CFZ2S74SHXBMoCkZSKNPNqFYraWYs6CH3.
Encrypted Version: a2552d6cadeacabe3f27d1fceee0384b.
First person to win gets the entire pot, of course it is likely there will be multiple winners and so it will be divided.
The last 2 digits of the block your transaction is wins.
To show I will not cheat and participate I will require all members to prove they own the address when they win and state they are not me.
Good luck. :-)
This is not a form of proof. There is no way for anyone to know that one of the participants is not you using this method.
Also, there is no way for anyone to know you will not walk away with the proceeds once they send the coins to your address. Use of a trusted escrow would help with the latter.