This article describes this as a "double transportation cipher" - which is incorrect. It's more correctly described in the article submitted nearly a week ago here:

https://news.ycombinator.com/item?id=6960168

That also has a link to a more complete description:

http://en.wikipedia.org/wiki/Double_transposition_cipher

"During World War I, the German military used a double columnar transposition cipher, changing the keys infrequently. The system was regularly solved by the French, naming it Übchi, who were typically able to quickly find the keys once they'd intercepted a number of messages of the same length, which generally took only a few days. However, the French success became widely known and, after a publication in Le Matin, the Germans changed to a new system on 18 November 1914. [1]"

https://en.wikipedia.org/wiki/Double_transposition_cipher#Do...

Courtesy of M. Édouard Snoden.

I think you meant: Mr. Édouard Neigedon.

Are we all Germans now?

OT but 4MB sure is a lot for a static site.

Came here to post this. Scrolling is a nightmare on this page. Why would you do this to your visitors? How would anybody still visit anyway?

Times like this, am very thankful for Readability[1]

[1]http://readability.com

I don't know much about encryption - can someone explain why if this was considered so "unbreakable" it was abandoned as a method so long ago?

Many codes are unbreakable (or are effectively so) if you only use them once, statistical attacks become possible with multiple messages. In this case if you send two messages of the same length with the same code both can be broken.

Also it's a rearrangement of the letters in the message. So a short message with distinct letters like 'Invade Pyatigorsk' could be easily cracked without knowing the code.