• Randomness beacon for eth.
• Requires 1 communication => 1 honest user out of everyone with a view of eth

Motivation and protocol design described here, here and here.

In brief, we feed blockhashes into a function that takes sufficiently long to compute that any miner that tries to compute the output of the blockhash (for example, to determine whether or not they will receive money due to the outcome) will forfeit the block. This forfeit is implicit in the ethereum mining protocol, as we rely only on the assumption that in the time it takes for a dishonest miner to computer the outcome, an honest miner will have submitted an unchecked block.