Subject: old unbroken WW2 cipher
Date: Sat, 09 Jul 94 07:08:36 GMT
A friend of mine gave me a copy of an "unbreakable" cipher,
that dates back to post WW2 and pre (nominal) computers. It
is believed to be a hand cipher, not table driven( though it
may be). The cipher appears to be based on a 25 letter
alphabet. This may be an extremely trival cipher to break,
but the process is unknown to me, or my friend, hence I am
putting into the great beyond for assistance. The replication
of the cipher below is as accurate as I recieved it, it has
been checked by row and column and therefore (hopefully)
error free (hopefully). Any help in the breaking and
method behind it would be appreciated.
75628 28591 62916 48164 91748 58464 74748 28483 81638 18174
74826 26475 83828 49175 74658 37575 75936 36565 81638 17585
75756 46282 92857 46382 75748 38165 81848 56485 64858 56382
72628 36281 81728 16463 75828 16483 63828 58163 63630 47481
91918 46385 84656 48565 62946 26285 91859 17491 72756 46575
71658 36264 74818 28462 82649 18193 65626 48484 91838 57491
81657 27483 83858 28364 62726 26562 83759 27263 82827 27283
82858 47582 81837 28462 82837 58164 75748 58162 92000
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Subject: Re: old unbroken WW2 cipher
Date: 9 Jul 1994 20:58:47 -0700
Keywords: D'Agapeyeff
This is the d'Agapeyeff Cipher, a one-off effort produced as a challenge
at the end of a cryptography book by Alexander d'Agapeyeff in 1939 -- so
it's pre-WW2. In my opinion d'Agapeyeff was not knowledgeable about
ciphers. He wrote a cartography book in a series for Oxford University
Press, so I assume he was later tapped for this one in the same series.
Quite a few people have had a go at it, and an article was written about
it in an early Cryptologia pointing out some of the statistical oddities.
My current theory is that he was trying to execute a Mirabeau cipher (like
a checkerboard with nulls) but botched the encryption in some unknown way.
This challenge cipher was removed from later editions; when interviewed he
said he no longer remembered how he had done it, according to an article
in The Cryptogram.
Rather than "unbreakable" I'd prefer to call it "as-yet unbroken".
Jim Gillogly
Trewesday, 17 Afterlithe S.R. 1994, 03:58
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Subject: Re: old unbroken WW2 cipher
Keywords: D'Agapeyeff
Date: Sun, 10 Jul 1994 11:48:00 GMT
Well, I feel better now. I spent a few hours on this one before
deciding it was beyond my ability. Unfortunately, my meager abilities
didn't take me very far.
I dropped the "000", natch, and counted 196 digrams, 18 unique.
Frequency counts suggested the distribution was very English-like, and
that solution would therefore involve substituting letters for numeric
digrams and possibly transposing.
Thinking in terms of a checkerboard alphabet (5x5), I did a quickie
substitution and looked at the result; setting it up as a 14 x 14 matrix,
I saw that the only three letters with frequency == 1 were at the ends
of rows 7, 8 and 9. Digram and trigram analysis of the matrix were
useless, which suggested transposition of some kind; the three-letter
clue suggested Nihilist transposition to me. Unfortunately for me, my
abilities aren't up to fooling around with a substituted transposition,
and I quit there.
What the heck, it kept me off the streets. The hubcaps of the neighborhood
were safe for a few hours...
--
Optimists say, "The glass is half full."
Cliff Sharp Pessimists say, "It's half empty."
WA9PDM We realists say, "Before I decide,
clifto@indep1.chi.il.us tell me what's in the glass."
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Subject: Re: old unbroken WW2 cipher
Date: Sun, 17 Jul 94 22:04:48 -0500
For further info, see Cryptologia, April, 1978. ``The Unsolved D'Agapeyeff
Cipher" by Wayne G. Barker, pp 144-147.... The code posted to usenet
is the same as that appearing in magazine.
(in other words no apparent errors).
The article poses four possibilities:
1) Has a form of transposition taken place within columns?
Between rows?
2) Has a form of "addition" taken place within columns?
This might explaine, for example, the last column on the right
which might have an "additive" different from other columns (Barker
is referring to the 14x14 matrix version of message)....
3) Do perhaps the numbers in the last column serve as some
sort of "check" or "indicating device" for the other two-digit numbers
within the same or next row?
4) Is it possible that a three-digit system is involved? Within
each row there are a total of 28 digits. If one digit serves as a check/
indicator, the remaining 27 digits divide into nine different three-
digit groups.....
Also..... "if the three final zeros are treated as nulls
then the only other zero in the cryptogram falls almost at the
midpoint of the message! Chance? Significant? It appears that the
cryptogram is certainly capable of being solved and a mathematical
approach in analyzing columns might eventually lead to solution.
Are the frequence distributions of odd columns compatible with
the frequency distributions of even columns? Are there other things in the
cryptogram that appear unusual? ... Might the cryptogram be broken
into two smaller squares or rectangles? These and
other questions make the d'Agapeyeff challenge extremely interesting.
...d'Agapeyeff, Alexander, "Codes and Ciphers" (London,
Oxford University Press, 1939)
Cheers and good luck...
Larry Harnisch
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