Today I Learned

I was reading The Codebreakers by David Kahn, and today I learned:

  • Étienne Bazeries was among the most badass cryptologists who ever lived (at least, as far as I’ve read). Noted as “the great pragmatist of cryptology” by David Kahn (a tremendous understatement), he tore through ciphers like tissue paper. I cannot understate how deftly this man manipulated ciphers and unlocked their secrets.
  • Sometimes this had hilarious results: someone sent a message to a duke in France, with many errors in its encipherment, yet Bazeries was able to solve it. The duke’s frustrated, contemptuous one-word response: “Merde.”
  • On a related note: I will never design my own cipher. Repeat after me: I will never design my own cipher. Write this on a chalkboard 50 times if you have to. Just don’t do it.
  • If you don’t trust me on the last point, consider this: Bazeries was able to solve the ciphers used by the French military, which at that point, was the largest military in Europe. If he could solve their ciphers, a modern cryptanalyst will be able to crack yours. Granted, they were wimpy ciphers compared to the systems Bazeries suggested, but still.
  • I didn’t technically learn this today, but: the Vigenère cipher was not created by Blaise de Vigenère himself, and was misattributed to him. It was actually invented by Giovan Battista Bellaso. However, Vigenère did create an even more powerful “autokey” cipher.

Over the past few week or so, as I’ve read Codebreakers, I’ve gained an immense respect for French cryptography in general. The “black chambers” were a fertile source of cryptanalysis, for one. On top of that, some of the greatest books on cryptography have come from the French. Most of all, France produced the great Étienne Bazeries, one of my new heroes.

More to come, folks…

4 Comments Today I Learned

  1. Dane Lyons

    I’m curious why you are so against writing a cipher. I understand that a cipher might be fundamentally insecure but don’t you think there is academic or entertainment value in writing a cipher?

    Reply
    1. Austin Pocus

      Maybe I should amend my previous statement: never write a production-grade cipher. Never write a cipher you’ll actually use expecting it to be secure, because someone with a lot more experience in cryptanalysis will break it.

      Now, if you’re doing it for education or entertainment, that’s actually really cool, and I’d like to hear about it. I’ve often thought about transposition-based ciphers as opposed to substitution ciphers, the latter being far more common, but I just read about a general technique for breaking any simple transposition cipher, so I might go a different route…

      Anyway, that could make a fun game of code-pong: write a cipher, send it to your friend, have them break it, they send you a cipher to break, and so on. What do you think?

      Reply
      1. Dane Lyons

        Nice. I like the idea of a code-pong style game where you send ciphers back and forth.

        Maybe instead of this being a game played between 2 people, it’s a game played by a largish group. One person starts by sending a cipher to a large group. The first person to break it, gets a point and gets to send the next cipher. The game could either be time capped or the first person to reach a score wins.

        Reply
        1. Austin Pocus

          That would be awesome! I could see a weekly leaderboard, and grouping algorithms similar to those used in online gaming, where you get matched with the group that most closely matches your skill level. One day, I’ll have to make code-pong a reality. One day…

          Reply

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