Re: Confirming Random numbers?

Everybody commits to a value (e.g. broadcasts the SHA1 hash of a large random value); everybody reveals their values (and checks that they match everybody else's commitments); now add all the values modulo whatever your number of choices is, and you have a shared verifiably random number. Now, there is one way to cheat this, which is to copy someone else's commitment (even without yet knowing their value) and then copy their value when it is revealed, thereby possibly forcing the choice to be even or whatever. So everyone should also check that all the commitments are different. Hal