86:"The cipher is of course easily made out, but if every third, fourth, or fifth letter, as may be previously arranged, is a dummy inserted after a message has been put into cipher, it is then extremely difficult to decipher unless you are in the secret."
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Additionally, D'Agapeyeff left two ciphers for the reader to solve. Each are approximately 100 characters in length and have an index of coincidence much higher than what is expected for
English plaintext.
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When deciphered with a
Polybius square, the plaintext of this exercise contains a mistake (based on mis-encoding "E" as "BE" rather than "CE"), but reads:
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117:, which the author used as examples in his book. He explicitly solves an example of a Polybius square based cipher from a friend in his
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It was not included in later editions, and D'Agapeyeff is said to have admitted later to having forgotten how he had encrypted it.
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141:"THE NEW PLAN OF ATTACK INCLUDES OPERATIONS BY THREE BOMBER SQUADRONS OVER FACTORY ARYA SOUTHWEST OF THE RIVER"
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It is possible that not all the ciphertext characters are used in decryption and that some characters are
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78:. Evidence for this is given by the author on p. 111 of the text under the sub-section heading
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for the D'Agapeyeff cipher is 1.812 when taken in pairs horizontally (e.g., '75' '62' '82'), the
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Barker, Wayne G (1978). "The
Unsolved D'Agapeyeff Cipher", Cryptologia, 2(2): 144-147
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Description of properties and potential decryption strategies for D'Agapeyeff cipher
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Shulman, David (nom: Ab Struse). "The D'Agapeyeff
Cryptogram: A Challenge",
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Offered as a "challenge cipher" at the end of the book, the ciphertext is:
31:, an elementary book on cryptography published by the Russian-born English
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distribution is too flat for a 196 character message written in
English.
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section of the book. This worked example consisted of 178 characters:
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Discussion of possible causes of failure to solve D'Agapeyeff cipher
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81657 27483 83858 28364 62726 26562 83759 27263 82827 27283
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71658 36264 74818 28462 82649 18193 65626 48484 91838 57491
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91918 46385 84656 48565 62946 26285 91859 17491 72756 46575
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72628 36281 81728 16463 75828 16483 63828 58163 63630 47481
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75756 46282 92857 46382 75748 38165 81848 56485 64858 56382
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74826 26475 83828 49175 74658 37575 75936 36565 81638 17585
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75628 28591 62916 48164 91748 58464 74748 28483 81638 18174
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Shulman, David (nom: Ab Struse). "D'Agapeyeff Cipher: Postscript",
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The structure of the D'Agapeyeff Cipher has similarities to the
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82858 47582 81837 28462 82837 58164 75748 58162 92000
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ACABD CBDCB AABDC ACEDC BABCD DCDBD DCBEB CDCBE BCAAB DACCD
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AABDE BCEDC BCCDA EBDCB AAEAB ECDDB DCCEC EEABD ADEAD CAADE
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CDDBC ECBCE BBEBD ABCCB BDBAB CCDCD BCDDE CAECB DDDAA CABCE
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304:, 1939, Oxford University Press, p. 158
350:Undeciphered historical codes and ciphers
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27:that appears in the first edition of
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132:DBBBC EAACD BDCDD BCEDC AECAC EDC
106:Use of Polybius square methods in
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334:American Cryptogram Association
39:Alexander D'Agapeyeff in 1939.
321:Another approach to decryption
294:, maintained by cryptographer
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292:List of famous unsolved codes
278:, April/May 1952: 39-40, 46.
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80:Military Codes and Ciphers
70:Use of nulls in ciphertext
300:D'Agapeyeff, Alexander.
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