The cover of a well-known cryptography book shows a 16-letter cryptogram. Its solution is unknown.

Martin Gardner (1914-2010) …

Source: Wikimedia Commons

… has been one of my favorite authors since my high-school days in the 1980s. At first, I enjoyed his numerous books on recreational mathematics, most of which are based on his legendary column in the Scientific American.

Later, when I became involved in the skeptics community, I learned that Gardner was also a devoted skeptic, who had published a number of notable books about the subject. Especially, his 1957 work Fads and Fallacies in the Name of Science became a classic (my skeptical book Planeten und Propheten was less successful, but I consider it a classic of the skeptical litertature, too).


Gardner’s crypto book

And finally, I learned that Martin Gardner also had a few claims to fame in the field of cryptology. Most of all, his Scientific American column was the place where the RSA crypto system was first published (“A new kind of cipher that would take millions of years to break“). Only later, RSA was covered by a scientific magazine.

Apart from this, Martin Gardner published a cryptography book titled Codes, Ciphers and Secret Writing.

Source: book cover

Codes, Ciphers and Secret Writing is certainly one of the less important books Gardner wrote. It covers manual encryption systems, such as the Caesar and the Vigenère, and explains some basic codebreaking techniques. Though I consider myself a Martin Gardner fan, I never thought that this work was a must-read for crypto enthusiasts.

Gardner dedicated his crypto book to a certain OSVVZ ZYTZC KJLQZ.

Source: Codes, Ciphers and Secret Writing

Two years ago, I asked my readers if this short cryptogram could be deciphered. Blog reader Thomas Bosbach found out that a Vigenère decryption with the keyword LOVE yielded the following plaintext:


I don’t know if this was really the intended solution. However, I find it hard to believe that this decryption is a mere coincidence.


The cryptogram on the cover

When I recently read a Facebook post by David Allen Wilson, I realized that there is another notable thing about Gardner’s crypto book: Nobody appears to know what the cryptogram on the cover means. Here’s a transcript:


Considering that we are dealing with 16 letters written in a square, a turning grille encryption seems to be a promising candidate. However, there are only two vowels in the ciphertext, which makes a transposition cipher extremely unlikely.

A few Facebook readers have commented on David’s Facebook post. For instance, Randall Williams wrote: “Nothing in the book mentions the cover at all […]. If you want to add to the list of what it isn’t, it isn’t a Caesar. […] I usually ignore cover art. You have to remember that they are usually created by an artist and the book author may not have had any say about the cover.”

Antonio Giovanni Colombo commented: “As far as I can tell, they [the 16 characters] are only random letters taken from the ones that form the title of the book and the name of the author.”

To find out more, it would be a good idea to check via a dictionary attack if a Vigenère decryption produces a meaningful result. Another candidate mentioned in the book is the Playfair; this hypothesis could be tested with a dictionary attack, too.

Of course, it is also possible that a more complex system was employed to create this cryptogram. However, it would, in my view, be an act of cheating if a cipher is used that is not covered in the book.

I f a reader can find out more, let me know.

Further reading: Introducing NKRYPT, a set of sculptures bearing encrypted inscriptions


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Kommentare (8)

  1. #1 Tony Patti
    28. April 2020

    Hi Klaus, this was fun.

    I agree with Antonio Giovanni Colombo’s comment “As far as I can tell, they [the 16 characters] are only random letters taken from the ones that form the title of the book and the name of the author.”

    and would further propose:
    1. The letter “i” was not used in the Cover Artwork because it is not “space filling”
    2. The words were filled into the 4×4: GARDNER (first), SECRET (second), and WRITING (third)
    3. Most of the time with alternatinve red then blue squares

    Word #1 GARDNER (in the right half):

    – – – G
    – – E R
    – – A –
    – – D N

    Word #2 SECRET (in the top half):

    – – S –
    C T E R
    – – – –
    – – – –

    Word #3 WRITING (with the vowel ignored as noted above)

    N – – G
    – – – R
    T W – –
    – – – –

    Putting these together:


    which leaves only “D”, “P”, “R”, and H” which is probably most closely related to “CIPHER”

  2. #2 Bill Briere
    Wyoming, USA
    28. April 2020

    As AGC and Tony suggested, these 16 letters appear to be drawn from the title of the book and the author’s name: “CODES CIPHERS AND SECRET WRITING MARTIN GARDNER.”

    Even with less than half of the 41 letters present on the cover, it’s clear that this is a transposition. But what does the key look like?

    Note that the P and the H appear only once each in both our assumed plaintext and the partial ciphertext. This could clue us in to the transposition route, since these are adjacent letters in the assumed plaintext word CIPHER.

    At first glance, this 4×4 grid looks like the center squares of a turning grille. With a 90-degree turn, the aperture where P appears would become the window for the H. However, the pattern doesn’t continue. (That doesn’t entirely rule out a turning grille. For example, the 16 squares might not be the center ones.)

    Another possibility is suggested by the knight’s-move relationship between the P and the H in the ciphertext. Could the encryption follow a route consisting only of this one chess move? (Historical examples of similar systems can be found.) The PH pair can be extended to PHE this way. WR and ART also appear. Of course, our search for more strings of letters to confirm this is stymied by the fact that we lose track of the horse every time it jumps outside the corral.

  3. #3 Zach Epstein
    28. April 2020

    I’m not 100% sure that I got the shapes exactly right but it’s a significantly challenging puzzle that incorporates the chess moves of a knight and a bishop which when completed create the word and the many shapes of “TETRAHEDRA” (plural form of tetrahedron). (I can’t post the screenshot here but I did on your Facebook post.)

  4. #4 Joe
    29. April 2020


  5. #5 David Oranchak
    29. April 2020

    @Zach Epstein
    Nice idea! But those rules are not very restrictive and you can in fact find almost 20,000 words that way:

  6. #6 Klaus Schmeh
    8. Mai 2020

    Shannon Larratt via Twitter:
    Did Martin ever mention that it is a cipher in his book, or was it just random letters.

  7. #7 Klaus Schmeh
    8. Mai 2020

    @Shannon: No, I don’t think Gardner ever mentioned this cryptogram.

  8. #8 Martin Jonsson
    31. Juli 2021

    Thank you for this post!

    I was pulling my hair trying to solve it, thinking it would be simple.

    I think Tony might be right with the small change that the name of the author is not required to use all the 16 code letters. The letters of the title with I and O omitted (Maybe since they look like one and zero?) are enough. Do not forget the “AND”.

    I think the lack of an M in the code makes the inclusion of his name a less attractive solution
    Kindest regards,