As promised a long while back (i.e. before I got caught up in pirate history minutiae, etc), I had some interesting emails from Cheltenham music teacher Allan Gillespie, describing his claimed decryption of Elgar’s well-known Dorabella Cipher.

Allan’s starting point seems to have been my hunch that the Dorabella’s first two words were likely to be “Forli, Malvern”, a modest little seed which he then grew out into his own complete decryption.

Specifically, he claims that it’s a vaguely Vigenère-like polyalphabetic cipher, with the key sequence AIUEGSOLXMKWCQZTDPBNYHFR rotated right by five places every eight plaintext characters, i.e.

AIUEGSOLXMKWCQZTDPBNYHFR - for characters #1 to #8
NYHFRAIUEGSOLXMKWCQZTDPB - for characters #9 to #16
ZTDPBNYHFRAIUEGSOLXMKWCQ - for characters #17 to #24
MKWCQZTDPBNYHFRAIUEGSOLX - for characters #25 to #32
GSOLXMKWCQZTDPBNYHFRAIUE - for characters #33 to #39 (etc)

Furthermore, Allan claims (I think) that the output from this gets mapped onto Elgar’s rotated-3 alphabet via this second table (which he presented in a transposed form to make it look as though the keyword was “HAUNTED” [+Y], but it’s actually no more than a monoalphabetic substitution alphabet):-

... N. NE E. SE S. SW W. NW
u.. A. N. E. Y. T. H. D. U.
uu. G. F. ?. R. M. I. ?. Z.
uuu ?. ?. L. B. S. ?. O. C.(Unplaced letters: K P Q W X)

Undo these two stages (he says) and you get a plaintext of:-

ForlE, Malvern Link
A. and Dai’s qko [=quick opinion?]
Met St Stephen ‘eighty six.
Wed at Brompton Oratory but owed takC Mogul ob’d.

He further believes the Dorabella cipher was “concocted by someone other than Elgar (possibly in the run-up to WWII when GC&CS were recruiting; possibly with Dora Powell’s connivance, more likely not)“.

Having said all that, I should add that I’m not entirely sure how serious Allan is about all this; and, moreover, the likelihood that Elgar would have used a messed-up Vigenère in combination with a second substitution stage seems to me to be as close to zero as makes no odds. But all the same, I’ve tried to reproduce Allan’s claim here as clearly as I can, just in case someone else wants to try to reproduce his results.

As you probably already guessed, I’m almost completely sure (as I indeed wrote to Allan at the time) that this “sits in the esteemed and excellent company of those such as Eric Sims and Tony Gaffney who have tried to solve the Dorabella’s cryptographic mystery rather at the expense of its historical mystery“. That is, neither the details (in the allegedly derived cleartext) nor the methodology (that Allan believes to have been used to encrypt the message) cast any light on Elgar, Dora Penny, their relationship, or any reason that such a devilish complex cipher system and linguistically idiosyncratic message would have been appropriate or even useful.

Allan response was that by replying in this way, I was (entirely unsurprisingly) acting in the same way that other cipher mystery establishment figures do, by working hard to “resist any attempt by an outsider to knock down [the establishment’s] battlements”.

Gosh darn it, but doesn’t it just turn out he’s got me bang to rights there? I indeed spend three nights a week chairing a secret cryptographic cabal downstairs at the Athenaeum Club library (or, failing that, Westminster School’s dining hall next to the Abbey) that decides how to misdirect plucky independent codebreakers away from the heretical and uneasy truths behind cipher mysteries. This website is, of course, simply part of our community outreach programme: and let’s face it, when the obfuscating powers of the NSA, GCHQ, and the Bilderberg Group get combined in this way, what chance do all you ordinary people stand, hmmm?

7 thoughts on “Allan Gillespie’s Dorabella Cipher decryption…

  1. Cryptographers and cryptanalysts have my unstinting admiration – I have zero talent for such things and empathise enormously with Dorabella who looked at the thing then put it in a drawer and forgot about it for decades.

    obviously not mad keen on ciphers and puzzles, as Elgar was in a position to understand.

    .Sometimes I wonder, just a bit, if cryptographers aren’t vulnerable to the ‘wrench’ syndrome – you know, the one where you ask your brother if he’s seen the eggbeater and he offers to lend you a wrench, because it’s a good wrench and he’s a mechanic, and the result’s much the same except for the bits of shell.

  2. bdid1dr on October 21, 2013 at 3:20 pm said:

    Not my usual “heh”, Diane! I just HAVE to use ROFL
    beady eyed wonder

  3. Helen Ensikat on October 22, 2013 at 5:00 am said:

    Poor amateur cryptographers. I do hate it when The Man is keeping me down.

  4. Allan G. on October 22, 2013 at 6:57 am said:

    Nick missed a couple of important points in his otherwise fair write-up.:

    The alphabet (call it Plain 1 or just P1) is constructed as shown below. Take the phrase “The team to beat at HQ” and strip out the repeated letters (working from the Left) to give THEAMOBQ. Insert this horizontally into an ‘asymmetric’ Transposition cage (middle row is offset 1 to the Left) and then extract the columns according to a given key (I’ve used A as an arbitrary starting point).

    5 7 9 2 1 4 3 8 6
    T H E A M O B Q
    C D F G I K L N
    P R S U W Z Y Z

    [Sorry if the spacing gets mangled. C is column 5 on its own, followed by QZ]]. Nick alluded to the corresponding Cipher alphabet, call it C1 (possibly a keyphrase beginning Haunted day and night ……).

    The 2nd point is that chars 40-87 are enciphered/deciphered using 2 different alphabets and a different Latin Square. I have the 24-char P2 but not C2 and have yet to fully establish their construction/derivation.

    Finally, he makes no mention of the 3-char cipher repeat at 49-51 and 73-75. This happens due to the slides in part 2 being non-regular. I have shown them to be 1,9,9,8,7,7 – 1 for char 40-41, 9 for 41-48. Then 9,8,7 (49-56 to 57-64 to 64-72)= 24 which gives an enciphering reuse 49-56 and 73-80 and a corresponding Plaintext repeat of WED (WED at Brompton Oratory but oWED etc). Hey ho.

    Allan G.

  5. Alan,
    Would you write such a cipher as an addendum to a note sent in plain by your partner to a person still recent acquaintence and with no known interest in ciphers?

    it seems such a very peculiar thing to do – from my point of view, anyway. That’s why I suspect it is not about words, but a note about notes. just a hunch.

  6. Allan G. on October 22, 2013 at 6:06 pm said:

    Diane (I hope that’s right),

    No – of course I wouldn’t! Far too complex! Far too silly!

    But if my name wasn’t Elgar but Knox or Turing or similar, and if I were devising a suitable test for potential recruits to GC&CS, I might resort to some of the devilish things to be found (IMHO) in the Dorabella cipher.

    Simon Singh in his ‘The Code Book’ apparently refers to the cipher being used as a test puzzle prior to WW2 – I’m simply extending the argument and saying it was made up by one of the team. {and that was my view before I got the hatted alphabet P1 solved, with the Keyphrase The Team to beat at HQ). Hey ho.

  7. Helen: no! Crush them like the ants they are! Crush! Crush! Crush! 😉

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