Two months ago, US book author A.J. Jacobs showed me the encrypted journal of psychologist Abraham Maslow (1908-1970). My readers did a good job in analyzing this cryptogram. Now, A.J. asks for additional help.

An encrypted diary posted on Reddit last year is still unsolved.

A. J. Jacobs, a successful US author and journalist, has provided me scans of an encrypted journal written by a renowned psychologist. Can a reader break it?

An encrypted diary recently posted on Reddit looks easy to solve, but so far nobody has broken it.

Gerry Haynaly has deciphered the encrypted diary I recently introduced. Here’s how he did it.

Blog reader Christof Rieber has sent me a potential solution of a major crypto mystery: the encrypted passages of Lady Gewndolen’s diary. Is Christof’s deciphering attempt correct?

Ignaz Meyer, a Bavarian teacher and town writer, wrote an encrypted diary. The content of this joural gives interesting insights into the life of a 19th century individual who had a drinking problem and was not very successful in his job.

In the 19th century, a sailor working on the Great Lakes kept an encrypted diary. Can a reader decipher it?

A French magazine article reports on an encrypted diary written by a pedophile priest. The plaintext is not known to me. Can a reader break it?

Canadian artist Zen Rankin has published two encrypted messages he created in his youth days. Can a reader break them?