Craig Bauer, mathematics professor and crypto history expert, lets his students solve old ciphertexts as homework. Here are three especially interesting cryptograms Craig’s students have to break.

Readers of this blog are certainly familiar with Craig Bauer, editor-in-chief of Cryptologia and author of the Book Unsolved! (if you prefer a German publication about the same topic, try my book Nicht zu knacken). The following photograph of Craig (left) and me was taken at the HistoCrypt in Uppsala, Sweden:


In his day job, Craig is a professor at the York College of Pennsylvania. As far as I know, Craig is currently the only professor in the world who gives university lectures in crypto history. I wish something like this had been available 25 years ago at the university I attended.

Craig is, like me, pretty much interested in “real” cryptograms, i.e., encrypted texts that were created for practical use, usually decades or even centuries ago. His students therefore have to solve cryptograms of this kind as a part of their homework.

An exercise sheet Craig uses is available online. Apart from a number of crypto excercises Craig created himself, this sheet contains many interesting “real” cryptograms, some of which are new to me. Of course, the solutions of all these ciphertexts are known (giving unsolved cryptograms as homework might be a little too hard for the students). In the following, I will provide the three most interesting ciphertexts contained in this collection.


The Cipher Detective

This cryptogram, which was created with a Polybius square, should be not too difficult to solve:


A prison code

Crime does pay – at least in the crypto literature. My blog posts about encryption methods used by criminals and in prison are usually very popular. Here is one I didn’t know before I read Craig’s sheet:



A strange code from a book

This one looks like a MASC, but who knows what it really is?



Solutions are wanted, but will be deleted

If you can solve one of these cryptograms, please leave a comment. Don’t be confused if I delete the solutions after a few days. If I won’t do this, this post might become very popular among Craig’s students – more than Craig wants it to.

Further reading: The Top 50 unsolved encrypted messages: 9. The Rubin cryptogram


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Kommentare (4)

  1. #1 pkrapp
    12. September 2018

    while craig bauer’s book is very strong, he’s not the only professor teaching crypto history – there are many in the US, although most who teach it in math or computer science depth don’t teach much of the history before 1930. those who teach the longer history of cryptology are in the minority, but they do exist…

  2. #2 Thomas
    12. September 2018

    The Chambers code is explained in the edition provided by Google books: This a combination of steganography and simple substitution:
    Taking only the crossed lines, you get stylized numbers (e.g. one crossed vertical line = 1) which stand for the letters of the alphabet (1=A, 2=B…).

    The plaintext:
    “I never saw you but once. I love you. Edith Inwood”

  3. #3 Marc
    12. September 2018

    The Prison code :

    . . .

  4. #4 schorsch
    12. September 2018

    The Chambers code is explained in the gutenberg edition as well; no idea why Craig says that the cipher isn’t included there.

    This code is insofar very interesting, as it is the oldest predecessor I’ve ever seen to the more contemporary and familiar 7-segment-display.

    I wonder, if Chambers has ever seen the the technical and commercial value of an electronically switchable display device using such a technology. The first patent on such a device has been granted four years after the first publication of chambers novella (.