Introduced to codes and ciphers by the Sherlock Holmes story, "The Adventure of the Dancing Men," and Edgar Allan Poe's "The Gold-Bug," I practiced making and solving secret messages (even communicating by Morse code with neighbor boys at night by using flashlights from upstairs windows). The only surviving one of several books I compiled as a child is shown open here, Secret Messages. It distinguished between codes and ciphers, gave formulas for invisible inks, and explained cryptanalysis.
Over the years, I have written about decipherment and applied my knowledge to real cases: exposing the hoax of the Beale-treasure ciphers, redeciphering the Oak Island cipher stone, translating (for a bibliophile) a mysterious text published by a secret society, and collecting and solving secret writings of old autograph books, postcards, etc. (See my Real-Life X-Files, 2001, 219-234; Mysterious Realms 1992, 53-56; and Pen, Ink & Evidence, 1990, 42, 176-178, 198. See also "Deciphering Da Vinci's Real Codes," Skeptical Inquirer, May/June 2007, 23-25.)