I'd make one minor modification to Rich's procedure: result is the
13th bit of a SHA-256 hash of everyone's "votes", which "vote" could
be any number they want to contribute, but it must be fixed & written
down (in some fixed sequence).
The problem with "odd" instead of "hash" is that every vote *counts*,
but in a way such that an additional vote is trivially guaranteed to
change the parity and hence the result; it is too easy to hide a
person or vote twice. With a hash -- even a hash of subsequences
of the list -- there is no simple relationship between the intermediate
result and the final result.
Yes, checking the SHA-256 hash of a long list can't be done
in anyone's head, but everyone's cellphone can do SHA-256.
At 06:26 PM 5/31/2017, rcs(a)xmission.com wrote:
>Announce in advance "an odd number of Heads is outcome A".
>Everyone in the crowd flips his own coin in private, and reports the
>answer in a sealed envelope, the "ballot".
>The ballots are opened in full view, and Heads are counted.
>No particular problems with a stuffed ballot box, or multiple voting,
>or individuals choosing to used biased coins or just plain cheat.
>As long as observers are sure that every ballot is counted, anyone
>who cares about the outcome has contributed his own version of a
>random bit.
>
>Rich
>
>------------
>Quoting Henry Baker <hbaker1(a)pipeline.com>:
>>In general, I don't think that any amount of *passive* observation
>>will be convincing.
>>
>>Science is only believable when *independent* experiments are
>>supplied with *independent* random streams of bits;
>>i.e., if I am allowed to perform the experiment myself using my own
>>source of random bits. ("Supply a wiggle in, and see what wiggles
>>out")
>>
>>Of course, this raises the following possibility (sci-fi writers,
>>listen up!):
>>
>>In the future, the NSA will be tasked as a monopoly providing all
>>necessary random bits. It does this by producing quantum entangled
>>pairs of particles, supplying the market with one of each pair, and
>>keeping the other particle in labeled storage.
>>
>>If/when the NSA customer "measures" one of the "market" particles,
>>the entangled particle will also assume the same state, so the
>>customer will have his random bit, and the NSA will also be happy.
>>
>>At 02:31 PM 5/31/2017, Dan Asimov wrote:
>>>You have to perform a random binary experiment in front of a crowd
>>>of people  so no fooling is allowed  in in such a way that
>>>everyone is convinced that the experiment was fair.
>>>
>>>The people include some technical experts but many who are not.
>>>
>>>What is the simplest / easiest / cheapest way to ensure that the
>>>crowd will be convinced that the experiment was fair (the two
>>>outcomes had an equal chance of occurring) ???
>>>
>>>ÂDan
>>>
>>>P.S. I do not have ann answer to this, but maybe there is a "best" answer.
