> also why would it be a good idea to use a centralized source of "entropy"....? why is NIST involved at all?
Actually there's a very good use-case for NIST's Random Beacon in [OpenTimestamps](https://opentimestamps.org/): preventing miners from backdating their blocks undetectably.
Background: The Bitcoin protocol constrains block timestamps to not be >2hrs in the future, by virtue of the (kinda weak) rule that nodes reject forward dated blocks. However, for a timestamp proof that rule is irrelevant: a forward-dated block is a weaker proof, not a stronger proof. Unfortunately the reverse is problematic: a Bitcoin block is valid so long as its timestamp is > the median time of the last 11 blocks; nodes will happily accept backdated blocks, with the only constraint on backdating being that you eventually push the difficulty up.
Now, if you assume it's only a small percentage of miners doing this, the median time past rule helps you a bit, but it's hard to model; if a majority of miners are backdating blocks, there's a risk of backdated timestamps being generated with significant (hours/days) of backdating. While that risk is mostly theoretical because it's easily detected, it'd still be nice to rule it out.
Since the NIST Random Beacon represents a nonce that NIST claims did not exist in the past, we can easily use it to constrain and detect block timestamp backdating, a useful improvement to the security of OpenTimestamps. While not a priority, I'll probably add support for random beacons to OpenTimestamps at some point, and have the calendars do this automatically as part of the timestamping process.
Of course, I wouldn't do this with just NIST: all blockchains act as random beacons, so it'd make sense to use a merkle tree of this NIST random beacon and a few other blockchains at the same time to achieve this.
And finally, yes, you're quite right: using the random beacon as a source of entropy is beyond stupid.
edit: Come to think of it, the simplest possible implementation of this would be a cronjob that just grabbed the latest beacon and timestamped it... All you need to achieve is proof that the block had a dependency on the beacon after all.
but people will do it anyway, the level of insanity out there is really high https://www.reddit.com/r/btc/comments/68pusp/gavin_andresen_... or even https://arstechnica.com/security/2015/05/crypto-flaws-in-blo...
also why would it be a good idea to use a centralized source of "entropy"....? why is NIST involved at all?