In 1931, codebreaker and book author Herbert Yardley published an encrypted message without providing the plaintext. Can a reader decipher it?

One of my favorite cryptology books was written by US cryptanalyst Herbert Yardley (1889-1958). Yardley started his career as a codebreaker during the First World War and later became head of the US State Department codebreaking unit MI-8. In spite of poor funding, Yardley’s team proved quite successful in breaking forereign diplomatic codes. While Yardley was less skilled as a cryptanalyst than his colleague and friend William Friedman, he did a good job in training and managing his codebreaking team, which became one of the best in the world of its time.

Source: Wikimedia

The American Black Chamber

In 1929 Yardley’s career came to an unexpected end, when Henry Stimson became the new Secretary of State. Like his pre-decessors, Stimson learned about the MI-8, which was a highly secret institution, only after he had taken office. Contrary to most other politicians, Stimson considered eavesdropping and codebreaking immoral and not acceptable. So, he shut down MI-8 and dismissed Yardley.

MI-8’s existence ended on October 31, 1929 – two days after Black Tuesday, which marked the beginning of the Great Depression. It goes without saying that the chances of a codebreaker to find a new job were extremely bad in this time. However, Yardley found a spectacular solution: he wrote a book, in which he described the top secret work of MI-8 in all detail. Titled The American Black Chamber, this book was published in 1931. It is available online.

The American Black Chamber became a huge success. Of course, the State Department and all still-existing US codebreaking units became extremely upset about this book. The friendship of Yardley and Friedman, who were the two most notable codebreakers of their time, immediately came to an end.

Of course, the State Department considered bringing Yardley to court, but a trial would have revealed even more information about the work of MI-8 than had already been published. So it was decided to better not charge Yardley. Instead, the State Department declared the whole content of The American Black Chamber mere fiction, though it was clear that nobody would believe this statement.

No matter, how one judges Yardley’s conduct, The American Black Chamber is a great book. Apparently, Yardley was a great author and skilled storyteller. If you are interested in crypto history, you should put The American Black Chamber on your bucket list.


A cryptogram

In his book, Yardley covers many authentic cryptograms and describes how they were solved. In addition, he provides an encrypted text as a challenge for the reader to solve. I blogged about this cryptogram five years ago (in German).

Source: The American Black Chamber

Blog readers Armin Krauß and Jan found the following solution:

THE ????????
E ANG R ? ??

As you see, a few parts are still missing. If a reader can fill these gaps, please let me know.


Another cryptogram

In addition to The American Black Chamber, Herbert Yardley published an article about cryptology in the Saturday Evening Post. In this article, Yardley provides another cryptogram, the solution of which is not given.

Source: Saturday Evening Post

Like the cryptogram described above, this one is probably encrypted in a simple letter substitution (MASC). Can a reader break it?

Further reading: An unsolved cryptogram by a German conquistador


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Kommentare (8)

  1. #1 Thomas
    24. Februar 2019


    Did you see someone tried to decipher the first message in Friedman’s copy of “American Black Chamber” with pencil (apparently not Friedman himself, according to the marginal note)? This attempt differs slightly from the solution provided by your readers. As to the unsolved “word” in the 8th line consisting of eight characters: Since these characters do not appear in the preceding text, they probably represent digits, so that the “word” represents the date on which the “note was made”: 2?.0?.1912.

  2. #2 Norbert
    25. Februar 2019

    As to the Saturday Evening Post cipher: Yardley gives a hint (“que”) which indicates a French, Spanish or Portuguese plaintext. Seems to be Spanish. Starting from line 2:

    Hace tres días que
    estoy en esta sinpática ha-
    cienda …

    It’s not easy to go ahead, given the poor scan and my poor knowledge of Spanish. I will try. Help appreciated 🙂

  3. #3 Tony
    25. Februar 2019

    Hope this is helpful – the word divisions are mine so take them with a pinch of salt!

    Recordad? Rafel
    Hace tres dias que
    estoyn en esta sinpatica ha-
    cienda ??iclinde agrad-
    able se imbo?ables re cuerdos
    ?iasque forma
    ranepoca en mivida qui
    ??as buena ?omald? depende
    te a cuerdas delano ?? eda
    velada se esta aranbochan
    doentu memoria sus pequenos
    en medis del juicio de
    esatie?a sera facil que te ol-
    vide ide esta pequina region
    qui ?iera volver mein vicible
    vici tara mi amiguitor afiny
    ver que destribueeltie??osi??eda
    te?teseps?ria tu amiga

  4. #4 Norbert
    26. Februar 2019

    @Tony: Great, thank you!

    The triangular symbol probably stands for double-R. See line 5: “imborrables recuerdos”.
    This is a bit surprising. I would rather expect double-L to have a symbol of its own, but apparently, it has not (line 12: “detalles”).

  5. #5 Thomas
    26. Februar 2019

    @Tony, Norbert
    There seem to be at least two more characters: dot under dash=ch, triangle=rr. Maybe like this:?

    “Hace tres dias que estoy en esta sinpatica hacienda chiclinde(?) agradables e imborrables recuerdos. Dias que formaran epoca en mi vida qui .mas buena o malo depende…
    Te acuerdas de la noche de la velada? Se estaran borrando en tu memoria sus pequenos detalles. En medio del juicio de esa tierra sera facil que tu olvides de esta pequena region. Quiciera volverme invisible y visitar a mi amiguito Rafin y ver que destribuye el tiempo si… unicamente en sus estudios que contetase por.. a tu amiga”

  6. #6 Thomas
    26. Februar 2019

    Sorry, left out a “n”: “contentase” in the last l

    In line 4 “chic, linde” (chic, beautiful) might refer to “hacienda”, though “linda” would be correct.

    Could that be a “z” at the beginning of line 8 (“quizas”)? unfortunately, the text contains no other “z”.

  7. #7 Breaker
    26. Februar 2019

    More info about Orange Sherbert, AKA Herbert Osborne Yardley can be found here:

    Bozo was involved in the operations of the American Black Chamber, working later for NY City banksters that were engaged in the use of a series of older templates in the Beale to conduct a second layer of its operations

    The FDR Death Card that Klaus also has on file is the key card for the ciphers to be reworked and the box ciphers and grilles used in the complications are shown on that page.

    They were notorious

    Enjoy the archives of the Beale I made…..there are a few surprises in that era of history to be talked about.

  8. #8 Klaus Schmeh
    3. März 2019

    @Tony, Thomas, Norbert: Thank you very much!! It seems, you are breaking the cryptograms faster than I can write about them. Great job!