A PhD student has come across an encrypted message written by a 19th century anarchist. Can a reader break this encryption?

“I’m a historian; found this coded message in an 1893 letter. Help?”

These words stem from a post recently published on Reddit. Thanks to David Allen Wilson for informing me about it. Here’s the coded message (I would rather call it encrypted) in question:


The author of the Reddit inquiry writes: “I am a PhD student in history writing my dissertation on anarchism in the US during the late-nineteenth century. This letter was from Mary Herma Aikin to Voltairine de Cleyre in June, 1893. I think the cipher is in English, but there’s also a chance it’s in French. At the beginning of the letter, Aikin said that she believed their communications were being monitored/censored by the US Postal Service, hence the need for a code. The rest of the letter discusses an ill-advised plan their friend ‘P’ is hatching.”


Voltairine de Cleyre (1866-1912), the recipient of the message, was an American anarchist, known for being a prolific writer and speaker, and opposing capitalism, the state, marriage, and the domination of religion over sexuality and women’s lives. I have found no information about the sender, Mary Herma Aikin.

As can be seen, the alphabet used by Aikin contains a number of symbols known from the Pigpen cipher. The following picture, which has got nothing to do with the cryptogram shown above, shows a few Pigpen examples:


Just like the Pigpen cipher, the encryption method used by Mary Herma Aikin is probably a MASC (monoalphabetic substitution cipher), i.e., a simple letter substitution. If so, it should be possible to solve it – even if the message is quite short.

According to the Reddit poster, the paragraph before the cryptogram reads as follows: “I lost last year $15.00, as absolutely as if it was sunk in the sea, through exactly such a plan as he proposed. I will get my regular attorney, who tried to save my money for me, to write out a legal opinion of the case, booked by advice to let it alone and I will send that to P. Of course I shall give no clue as to whom I want the opinion and advice for, nor his place of residence. In haste but with dearest love, Herma.”

Can a reader break this encryption?

Further reading: Who can decipher this encrypted text in a Linkin Park video?

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Kommentare (20)

  1. #1 Thomas
    29. September 2017

    This has already been solved on reddit:


  2. #2 Thomas
    29. September 2017

    Obviously this isn´t a simple monoalphabetic substitution, since there are homophones for “A” and “E” and special signs for spaces and period (triangle an reversed triangle).

  3. #3 Jim Gillogly
    United States
    29. September 2017

    Googling provided a little background: Dr. Mary Herma Aiken of Grinnell, Iowa headed a small group of IWPA anarchists. Other IWPA associates were implicated in the Haymarket bombing in Chicago, 1886, seven years before this letter. Seems understandable that she would suspect their mail is being monitored.

    The other Aiken hit I found was her epitaph for another friend.

    I’d decided it was homophonic and that the triangle separated words… then Thomas’s messages came. I need to do more timely research!

    I suspect the word “FURTH” in the proposed decryption is wrong, but I don’t have a substitute with full support. It appears to be a 4-letter word rather than 5 letters. I suspected an imprecation aimed at Peter’s carelessness at first. The second letter is indeed U, but I think we don’t have other ciphertext examples of the other 3 letters. I suggest “BURN”: the B is similar to the one in BY, and the R is related to the M-shaped one. That just leaves the N as an unexplained homphone.

  4. #4 Jim Gillogly
    29. September 2017

    The link to a Haymarket history (volume 2) that I referenced in my first paragraph above no longer comes up on Google. Hmm. Here’s another link to her: https://atom.grinnell.edu/atom/index.php/aiken-mary-h-dr

  5. #5 Jim Gillogly
    29. September 2017

    Hah! I had the Haymarket link in my Google history:

    The link I posted above is to a file of her Haymarket-related correspondence.

    And her gravestone is online: https://goo.gl/kPni18
    July 1829 – 7 March 1902.

  6. #6 Marc
    29. September 2017

    FURTH ist wahrscheinlich FULL (das + als Verdopplung!)

  7. #7 Thomas
    29. September 2017

    “Full”? Dann sollte das Zeichen vor dem + das Zeichen für L sein. Das L aber wird aber an allen vier (anderen) Stellen mit dem gespiegelten F chiffriert, weshalb ein Homophon und damit ein zweites Zeichen für L wohl ausscheidet.
    Burn halte ich eher für möglich, wenn auch das erste Zeichen anders als das B in “by” einen Strich hat und dann das “n” als einziger Konsonant ein Homophon hätte. Furth. als Abkürzung für “further” – zwar 5 Buchstaben – aber wenn das “th” als das wohl häufigste Bigramm im Englischen mit nur einem Zeichen chiffriert ist… Letztlich wird sich das wohl nicht entscheiden lassen, weil drei Zeichen – bis auf vielleicht ein schludrig geschriebendes Zeichen für “R” – nur in diesem Wort vorkommen.

  8. #8 Marc
    29. September 2017

    Hier mal der entsprechende PP-Code :

    G|M|C (ohne Punkt)

    J|P|D (mit Punkt)

    \S/ (ohne Punkt)

    \U/ (mit Punkt)

    Ich halte beide für das gleiche Zeichen bzw. ein umgedrehtes F gibts da gar nicht, dass ist denke ich das gleiche Zeichen bzw. der Strich ist eigentlich ein Punkt, nur etwas undeutlich geschrieben. Nur A und E scheinen neben den normalen Symbolen eine 2. Ersetzung zu haben. Gut, ist nur eine Vermutung, man bräuchte mehr Daten.

  9. #9 Marc
    29. September 2017

    Huch, warum sind denn die Striche plötzlich so lange, dass war nicht beabsichtigt.

  10. #10 Thomas
    29. September 2017

    @ Marc
    Gegen + als Verdoppler spricht aber, dass “CARLESS” mit zwei S, also ohne Dopplerzeichen geschrieben ist.

  11. #11 Jim Gillogly
    29. September 2017

    Filling in the pigpen gives more insight, but doesn’t definitively resolve FURTH/BURN/FULL.

    We have no attested symbol for FGJPQVZ. The “normal” pigpen (pound sign, number sign, octothorp, hashtag) reads vertically ?HI/MNO/CAB so G is the obvious letter for the top left. The “dotted” pigpen reads vertically ?KL/P?R/DE?, so J, Q and F are the obvious remaining characters, in that order. The normal X-shaped pigpen is SWT? and the dotted X is UXY?, so the remaining V and Z presumably fill those two in. The “dotted” pigpen uses lines as well as dots: attached lines from the center of a line for DLR, centered dots for KPUXY, and either for E. The other homophones for AE are not pigpen-related.

    In the mystery word, the three missing letters don’t fit the dot/line pattern: the first is a B, or an F with its vertical line *outside* the character, the third is a partial R with an extra dot, or a partial L with an extra dot that’s outside the center and an extra short line going down from the top left.

    That leaves the + at the end of the word as the only letter with no hint from the pigpen. It must be a homophone of something, since all the letters are now assigned. Since both the first and third letters appear to be variants of a pigpen symbol, I expect them to represent one of those symbols rather than a homophone of an unrelated letter.

    So we’re still left with [BF]U[LR]+. I submit that the + is likely a common letter such as ETAOIN.

    I still like BURN: it fits well with the “mailing” carelessness, and with the EXPLANATION.

  12. #12 Narga
    29. September 2017

    I’m with Marc on FULL. The Pigpen grid seems to be used in a flexible way with the dots and the attached lines. Here is my suggestion:
    As for the selection of the A and E homophones, I don’t think there is a rule proscribing the use of + _every time_ there is a letter doubling (as in carless). And FULL EXPLANATION just fits the context perfectly (by mail! the full explanation!) at least to a native German speaker.

  13. #13 Marc
    30. September 2017

    BURN passt auch super. Ich war nur wegen dem Zeichen des R irritiert, da das eher nach einem L aussah. Der kleinere Strich links wirkte erst wieder wie ein Punkt, allerdings habe ich dann gesehen, dass da noch ein zweiter Punkt etwas versetzt und außerhalb zu sehen ist, was dann doch wieder zu BURN passt. Denn wäre nur der linke Strich ziemlich “verkümmert”.
    Vielleich gibts noch mehr Briefe hiervon ?

  14. #14 Jim Gillogly
    30. September 2017

    “full explanation” fits just as well to a native English speaker also. After your message I looked again at the R vs L question, and I agree that it’s harder to make it into an R than an L: the “zweiter Punkt” you noted looks like it could be the starting point of a full line along the top, with the short line coming down being a messy dot inside (which doesn’t fit with the rest of the L’s, which use a full line attaching to the right). I too would like to have it settled with more letters, perhaps from either of the two repositories that have been mentioned!

  15. #15 Thomas
    30. September 2017

    Maybe a three letter letter word followed by + for “and”?

  16. #16 Lercherl
    30. September 2017

    FURTH short for “further”? meaning something like “Furth[er] explanation [later].

  17. #17 Jim Gillogly
    30. September 2017

    Maybe, but I’d expect a triangle to separate the 3-letter word from the “and”. I don’t have a suggestion for a 3-letter word followed by “and” that would make as much sense between “careless” and “explanation” as BURN or FULL. Can you suggest one? I still wish I could make an obscene 4-letter word fit there. 🙁

    I still don’t like FURTH. No other word has been abbreviated; no other symbol represents a digraph; and in any case she’d only save two letters by abbreviating. Also, “Further” would mean there was some explanation already, and the following would add to it. To me the “would not dare use it now” is the explanation, not a further explanation. But I may be overthinking it.

  18. #18 Thomas
    1. Oktober 2017

    I think “burn explanation” sounds good, maybe she feared the cipher could have been revealed through Peter’s fault.

  19. #19 Esme
    1. Oktober 2017

    What about “burned”? – (I) burned explanation

  20. #20 Klaus Schmeh
    6. Oktober 2017

    Thanks to all! Apparently, somebody on Reddit solved this cryptogram first, but you added some information.