Gentlemen reading mail part II (opsec review)

[sunder]

Major Variola (ret) wrote:

> Sunder's suggestion of introducing information and watching for their
> response is good, though the Adversary will not respond if they're
> smart and they're watching you for something more important.
> 
> (What was that Brit town sacrificed so the Germans wouldn't know
> the codes were broken?  Starts with "C"...)

Coventry.  Story goes Churchill had info from Bletchley Enigma intercepts 
that Coventry was next to be bombed, but if he evacuated it, the Germans 
would have suspected that Enigma was cracked.  I've also heard references 
that this was an urban legend, not sure.

However, they did sink quite a lot of subs based on triangulation + Enigma 
decrypts by fortuitously sending an airplane in the area they knew the subs 
would be before hunting them down - as cover to say that the subs were 
spotted...  This way they could sink the subs and still let the Germans 
think that Enigma was safe.