Comment Comment by edent My favourite Enigma message - as told to me by a tour guide at Bletchley Park - was thought to be a stream of indecipherable gibberish.Until a WREN noticed that the message never contained the letter Z.One weakness of that generation of Enigma was that it could not self-encode a letter. That is, A was never encrypted to A.This had no letter Zs. A statistical improbability. Unless, so she reckoned, the entire message consisted of only the letter Z repeated.Apparently, their best guess was that a bored soldier sent a stream of Zzzzzz to a friend. That was enough to crack that day's key.Of course, every guide at Bletchley has a range of stories they tell credulous geeks. But it is a delightful tale of how OpSec is everything. parent edent 3 years ago
Until a WREN noticed that the message never contained the letter Z.
One weakness of that generation of Enigma was that it could not self-encode a letter. That is, A was never encrypted to A.
This had no letter Zs. A statistical improbability. Unless, so she reckoned, the entire message consisted of only the letter Z repeated.
Apparently, their best guess was that a bored soldier sent a stream of Zzzzzz to a friend. That was enough to crack that day's key.
Of course, every guide at Bletchley has a range of stories they tell credulous geeks. But it is a delightful tale of how OpSec is everything.