Question

BitcoinLotto:

Suppose the nation of Bitcoinia has decided to convert its national lottery to use

Bitcoin. A trusted scratch-off ticket printing factory exists and will not keep records of any

values printed. Bitcoinia proposes a simple design: a weekly run of tickets is printed with an

address holding the jackpot on each ticket. This allows everybody to verify the jackpot exists.

The winning ticket contains the correct private key under the scratch material.

7.1. What might happen if the winner finds the ticket on Monday and immediately claims

the jackpot? Can you modify your design to ensure this won’t be an issue?

7.2. Some tickets inevitably get lost or destroyed. So you’d like to modify the design to roll

forward any unclaimed jackpot from Week n to the winner in Week n+1 . Can you

propose a design that works, without letting the lottery administrators embezzle

funds? Also make sure that the Week n winner can’t simply wait until the beginning of

Week n+1 to attempt to double their winnings.

Answer 1

7.1 The tickets can be issued to everyone. But on scratching, but verification should be allowed on the last day of the week, that is Saturday. The key to unlock the bitcoin should be date protected and should be activated on the last working day of the week. So that even if a person purchasing ticket on Monday tries to unlock immediately, he will not be allowed to until the last day of the week. In this way there can be fairness

7.2 If some tickets are lost or destroyed, then as per the present bitcoin nature, there is no way to unlock the bitcoin. The only way to prevent this would be to secure the printing so that there is no possibility of theft or destruction in the ticket production process.