No one knows for sure why Poe liked what he called secret writing. He may have enjoyed the intellectual exercise of turning plain English into ciphers and deciphering them. He may have found it an intriguing subject that not very many people knew a lot about. He may have liked it because it allowed him to show off to his readers. Whatever the reason, Poe did seem to enjoy this kind of mental challenge, and sprinkled his writings with references to it.
When he served as editor of Alexander's Weekly Messenger, Poe issued a challenge to his readers. They should send him cryptograms and he would decipher them. He placed some restrictions on the kinds of messages readers could send. All of them had to use a simple substitution one letter of the alphabet had to stand for another and have the words in the cipher separated with spaces as they would be in a normal sentence.
Later, when he worked for another magazine (Graham's Magazine) Poe brought up the subject again. He claims to have solved the 100 cryptograms submitted to the Messenger. He also wrote an article for the magazine about secret writing. In it, he explores secret writing and the history of secret writing. Experts in the field think he may have borrowed many of the facts in the article from an encyclopedia entry. They also say Poe's cryptograms are at best-very simple ones to decipher. The complicated part for Poe, they say, was in convincing his readers that he was an expert cryptographer. He easily accomplished that task, though, because not many people at the time knew a lot about cryptography, and Poe was a very convincing writer.
Poe also published two cryptograms he said came from a reader called W.B. Tyler. Poe never solved these puzzles. He said it would take too much time-time that he needed for writing. So, the cryptograms remained unsolved . . . until a few years ago.