[Cryptography] highlights of crypto history

[John Denker]

On 11/13/2016 05:39 PM, ianG asked:

> What is the most important message ever protected or not protected? What day was it sent?

Innnnteresting question.

Here are some candidates that spring to mind:

Security failures:

  Zimmermann Telegram : 11 January 1917 -- encrypted, but not quite well enough.
   From a US/UK point of view, this one is hard to beat.

  First Battle of the Masurian Lakes : 8-11 September 1914 -- the Russians had
   a bunch of these newfangled "radios" but they didn't have their cryptologic
   act together, so they transmitted in the clear.  The Germans picked up on
   this.  This could be considered the start of a years-long series of very
   unpleasant events for the Russians.  (David Kahn likes to cite this example.)

   The Bolsheviks learned from this, and have ever since devoted tremendous
   efforts to crypto, comsec, and opsec.

Security successes:

  Battle of the Bulge : 16 December 1944 -- Germans achieved essentially complete
   tactical surprise, effective comsec (not so much crypto, just low-tech comsec),
   effective deception.

  Operation Overlord : 6 June 1944 -- Allies achieved essentially complete tactical
   surprise, highly effective deception.



Other contenders:

  Washington Naval Treaty : signed 6 February 1922
    US codebreakers ate the Japanese diplomats' lunch.
    Nontrivial consequences for WWII.
    Consequences would have been greater if Yardley hadn't spilled the beans.

  So many aspects of WWII that one hardly knows where to begin:
    Battle of the Atlantic
    Battle of the Coral Sea
    Battle of Midway
    Assassination of Yamamoto
    US anti-shipping operations in the eastern Pacific, unheralded but very consequential,
      dependent on breakage of Japanese Maru code and non-breakage of US Navy codes.