Verifiable Random Selection - Advice
The RFC has more detail and rationale, but here's the quick version:
- Construct and publish your list of things to choose from. If this involves people making submissions, publish a date and exact time (with timezone) after which no more applications will be accepted.
- Do not change the list after that date. If entries must be withdrawn, just put a line through them and, if the algorithm picks them, ignore that result and get it to pick again.
- Publish an ordered list of 3 specific sources of randomness. I strongly suggest draws from the UK National Lottery - specify both the game names and the date(s) concerned. As of late 2016, they make 3 draws every Saturday (Lotto, Thunderball and Lotto Hotpicks) which is coincidentally just the right number of sources of randomness. Don't forget to specify if the Bonus ball/Thunderball is excluded or included. If you don't do this, read the RFC for more advice on picking good sources.
- Insert the list and the random values into the web app, once the draws have been made.
- Click "Get Result" as many times as necessary.
- Invite other interested parties to check your working.
- For bonus points, construct and compile the C source code to reproduce the results and so check there's no bug in the web app ;-)