On a US website, a cryptogram from the Civil War is introduced. The plaintext is written below it. Can a reader find out if the decryption is correct and what cipher has been used?

The US Civil War (1861-1865) was the first war in history, in which telegraphy played a major role. For obvious reasons, telegraphy messages had to be encrypted – a task that proved difficult, as both sides had no experience in cryptography and no trained cryptologists at hand. For this reason, the encryption systems applied in the Civil War were not the best. Many did their job anyway, as the codebreaking skills of the war-leading parties were not especially sophisticated, either.

On a US stamp dealers website I recently found the following cryptogram from the Civil War:

Source: Public Domain

This cryptogram is noted on the rear-side of an envelope. The address written on the front-side is “James M. Rawlings, Rockbridge Artillery, Hardaway’s Battery, Army of N(orthern) V(irgini)a.”

Source: Public Domain

The first question is why this message was written on this envelope. My guess is that somebody simply used the envelope as a note sheet. There is not necessarily a relationship between the cryptogram and the recipient of the letter.

The next and probably most important question is what the message means. This question is seemingly easy to answer, as the plaintext is written below the encrypted message. It reads as follows: “caisson, canteen, Spotteswood, louse, pirated”. According to the stamp dealer page, “Spotteswood” might stand for a hotel located in Richmond, Virginia. Apart from this, I don’t understand this message. Are the words “caisson”, “canteen” and so on taken from a codebook? Is the decryption correct at all?

If the decryption is correct, it is clear that a polyalphabetic cipher was used. This can be seen, for instance, in the first line, where both 1 and 22 stand for the letter “s”. The most important polyalphabetic cipher used in the 19th century was the Vigenère cipher. In fact, it is known that the Vigenère cipher was applied by the Confederates during the Civil War. This is described on the website of Satoshi Tomokyo as well as in Craig Bauer’s book Unsolved!. Here’s what Craig writes about this topic:

The Vigenère cipher has seen extensive use over hundreds of years. It was used by the Confederacy in the Civil War, and it had long been believed that they only ever used three keys: MANCHESTER BLUFF, COMPLETE VICTORY, and (after General Lee’s surrender) COME RETRIBUTION. In 2006, however, Kent Boklan, attempting to break an old Confederate message, discovered a fourth key [BALTIMORE].

Is this cryptogram noted on the envelope Vigenère-encrypted in one of these four keys?

According to the stamp dealers site, a cipher disk might have been used for encrypting the cryptogram on the envelope. This is certainly possible. As my friends Marc Simons and Paul Reuvers write on their Cryptomuseum website, the Confederates in fact used a cipher disk for Vigenère encryption (such a disk is not really necessary for a Vigenère cipher, but it makes enciphering a little easier).

Can a reader find out more about this cryptogram? If so, please leave a comment.

Further reading: Who can break the cryptograms of Civil War spy Robert Bunch?

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Kommentare (4)

  1. #1 Klaus Schmeh
    21. Dezember 2018

    Sam Taylor via Facebook:
    Hi Klaus Schmeh, why didn’t you include “Itch” and “Trout” under the plaintext? or did i miss it in the article?

  2. #2 schorsch
    21. Dezember 2018

    The same number is ever represented by the same character, but same characters are represented by different numbers. That is, e.g., each occurence of 20 is transformed into O, but O might be transformed into 13 (in caisson), 20 (spottes, louse, trout?) or 3 (trout).

    So the characters might be the codeword, and the clear text will reveal, if we simply order the numbers ascending from 1 to 23. The numbers 6 and 16 are missing (as far as I can read this Sauklaue), so the complete sequence reads
    “spots vlyanlocu rthouse”. That is not exactly, but very short to Spotsylvania Court House, theater of one of the major battles of General Grant’s Overland campaign.

    Possibly the author of this letter has tried to inform Rawlings (and, maybe, through Rawlings his homefolks) about his own current whereabouts, but to conceal this from the military officials. Not a very bright trick at first glance, since such suspicious wish-wash might easily arouse suspect of espionage.

    But the idea might as well have been, not to deceive the southern military authorities, but northern intelligence officers in case of an interception of the letter.

  3. #3 Richard SantaColoma
    21. Dezember 2018

    It looks to me like a more simple substitutions, with some variables, errors, and incorrect “corrections”. For instance, “8” is probably supposed to be “H”, for “house”.

    As for “caisson, canteen, Spotteswood, louse, pirated”, then, maybe:

    “caisson, canteen, Spotteswood House, pirated”, which may mean something along the lines of, “We pirated (stole/siezed) a caisson (gun on carriage) and a canteen (food/supply wagon) near the Spotteswood House”.

    Just a guess.

  4. #4 schorsch
    21. Dezember 2018

    The following list might be easier to understand. First column the number, second the assigned character, third the word, in which this number/character combination appears first (hope my formatting survives):

    1 s caisson
    2 p pirate
    3 o trout
    4 t itch
    5 s louse
    7 v trevy
    8 l louse
    9 y trevy
    10 a caisson
    11 n caisson
    12 i caisson
    13 a canteen
    14 c caisson
    15 u louse
    17 r trout
    18 t trout
    19 h itch
    20 o louse
    21 u trout
    22 s caisson
    23 e canteen

    One question remains: What stands the last word “trevy” for? No idea, but for the time of the civil war there is a family Trevy traceable to Staunton, Va. and a Captain Trevy in the famous ‘Stonewall Brigade’ in the Army of Northern Virginia