[Cryptography] Brute force circa 1939

[John Denker]

On 11/13/18 6:24 PM, Grant Schultz wrote:

> I would bet it was Hollywood that was naive here.  William Friedman
> or many others in Washington D.C. would have known that 2371
> possibilities was far too few to withstand cryptanalysis.  (Although
> it would be interesting if there were evidence that Washington folk
> insisted that Hollywood use that low number.  Any way to find out?)

This is clearly just Hollywood being lazy.

The Enigma machine entered the commercial market in 1923.
Non-military versions (without a plugboard) have a keyspace of
712,882,560 if I've done the math correctly.  Anybody who knew
anything about the unclassified state of the art would have
known this in 1939.  Censors don't care about stuff that has
been widely known for years.

I am reminded of the Batman movie where people watch a
thermonuclear bomb go off a few miles away.  Even though
it is a few miles away, the sound and the light arrive
at the same time.  And even though it is only a few
miles away, the city is not incinerated.  The filmmakers
weren't trying to protect top-secret weapon info.

There are plennnty of additional examples:
  https://tvtropes.org/pmwiki/pmwiki.php/Main/CriticalResearchFailure