In 2017 I blogged about a Pigpen ciphertext that had been discovered in the London suburb of Croydon. This cryptogram is still unsolved.

Two years ago, a woman from Croydon (a suburb of London) found the following encrypted text (I call it the “Croydon cryptogram”) on the floor next to her house:

Source: Reddit

Apparently, this woman had a nephew who knew that there is a Reddit discussion group named /r/codes that deals with unsolved cryptograms. He took a picture of the ciphertext and published it there.

A few Reddit users commented on this cryptogram, but most comments were not very helpful. For instance, one user wrote “it reminds me of Tic-Tac-Toe”, while another stated: “They remind me of rogue signs or thieves’ cant.”

To somebody familiar with cryptography it is clear that this message is probably something completely different: it looks like an encrypted note created with a variant of the Pigpen cipher. The Pigpen cipher is a Monoalphabetical Substitution Cipher (MASC) that is created with a diagram like the following:

This a diagram can be varied in many ways. Especially, the order of the letters can be changed. For this reason, knowing that we deal with a Pipen cipher doesn’t mean that the cryptogram is solved.

In 2017 I published a blog post about the Croydon cryptogram and a few other cipher mysteries I had found on Reddit. To my regret, nobody came up with the solution. So I decided to write about this unsolved ciphertext again.

Here’s a transcription of the Croydon cryptogram (some of the glyphs are hard to read, so I can’t guarantee that everything is correct):

As can be seen, there are four words that consist of four letters each and that have the same character (a U with a dot) twice in the middle. This is very unusual. Provided that the plaintext language is English, the U with a dot almost certainly stands for the E. The four-letter words in the cryptogram might decrypt to SEEN, BEEN, KEEN, SEES, BEES, MEET or something similar. Perhaps, one of these words can be used as a crib.

Usually, a skilled codebreaker has no trouble solving a Pigpen message like this. So, I hope, this one can be broken, too. If you have an idea about how it may work please let me know.

Further reading: A German spy message from World War 2


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Kommentare (4)

  1. #1 hmm
    28. Januar 2019

    At least in 2 of the 3 you left undotted, i see dots. Even without that, there are so many dotted ones, the position of that dot might play a role (left-right of the square(-part) instead of dot-no dot).

  2. #2 schorsch
    28. Januar 2019

    An english wordlist shows 113 occurences of four character words with enclosed oo (Moon, Tool, Soot…) and only 108 occurences for ee (Beer, Deep, Keel…). So the dotted U stands for O as probable as for E.

  3. #3 Klaus Schmeh
    28. Januar 2019

    Joe McNicholas via Facebook:
    Too many (*) inside of symbols should be half and half.

  4. #4 schorsch
    29. Januar 2019

    There are too much asterisks, indeed. But demanding half’n half is extremist. That wouldn’t fit that obvious nursery rhyme scheme.

    I think, that this strange graffitto is nothing else but just an graffitto – no encryption at all. But if it is an encrypted _english_ text, than I guess it’s some wordplay – maybe nursery rhyme, more probably some slang expression (which might include rogue signs). In this case, if classical pigpen, there should be expected at least two or three non dotted characters -but not a statistical balance.