Like other literary figures of his time, Edgar Allan Poe had an intense interest in cryptography. Although he never revealed his methods, Poe believed that breaking ciphers and other enigmas was required the straightforward application of reason and logic.
In terms of his cryptographic interests, Poe is best known for his famous challenge, issued in December 1839 in Alexander's Weekly Messenger, that he could solve any simple substitution cipher that readers of the magazine cared to submit. A simple substitution cipher is one in which the same symbol stands for the same letter of the alphabet in the concealed message. Poe's challenge also insisted that the cryptograms preserve the word boundaries.
In his own words, Poe's challenge is stated as follows:
"It would be by no means a labor lost to show how great a degree of rigid method enters into enigma-guessing. This may sound oddly; but it is not more strange than the well know fact that rules really exist, by means of which it is easy to decipher any species of hieroglyphical writing -- that is to say writing where, in place of alphabetical letters, any kind of marks are made use of at random. For example, in place of A put % or any other arbitrary character --in place of B, a *, etc., etc. Let an entire alphabet be made in this manner, and then let this alphabet be used in any piece of writing. This writing can be read by means of a proper method. Let this be put to the test. Let any one address us a letter in this way, and we pledge ourselves to read it forthwith--however unusual or arbitrary may be the characters employed. " [C.S.Brigham, Edgar Allan Poe's Contributions to Alexander's Weekly Messenger, American Antiquarian Society, 1943. ]
Between December 1839 and May 1840, Poe appears to have solved all of the ciphers submitted to Alexander's. He himself claimed that "out of, perhaps, one hundred ciphers altogether received, there was only one which we did not immediately succeed in solving. This one we demonstrated to be an imposition -- that is to see we fully proved it a jargon of random characters, having no meaning whatsoever."
Scholars who have studied this have concluded that Poe did appear to meet his challenge. In an article entitled "What Poe Knew About Cryptography," W.K. Wimsatt of Yale counted 36 ciphers in Alexander's, and gives the following accounting: Poe printed the text and solutions to 9 ciphers and he printed the solutions (or part of the solutions) to 15 ciphers; he simply states that he has solved 3 ciphers; he states that he did not solve 6 ciphers, which were defaced, although in one cases he provided a proof that the submission was not a valid cipher. All of these 34 are believed to be simple substitution ciphers. In addition, Poe appears to have solved a cipher which some symbols to stand for more than one letter of the plain text and in one case a cipher in which 7 different alphabets were used. In this last case, since we don't have the cipher text itself, it is believed that a new alphabet was used on each line of the plain text, rather than a cipher such as Vigenere's.
The following cryptogram printed here occurred in the April 22, 1840 edition of Alexander's.
C'WW WPB VKI WPYKIY UN BI VKONJ
C'WW NZV BI VU VKI XIEB DZCNJ
PFL WPJI BI YVPEV
IPNK AUWWB YKPWW EINIOXI MB YVCFL
IPNK UCNI ZFVU MB AIIV CWW GECFL
PFL MPJI CV YMPEV.
It happens to be one of the more challenging posers since it has a couple of instances in which the the same cipher symbol stands for two different plaintext letters. However, upon solving this cryptogram, Poe remarked,
"we say again deliberately that human ingenuity cannot concoct a cypher which human ingenuity cannot resolve."