with theories about the nature and existence of fairies and spirits. In his The History of Spiritualism (1926) Conan Doyle praised the psychic phenomena and spirit materialisations produced by Eusapia Palladino and Mina "Margery" Crandon. His work on this topic was one of the reasons that one of his short story collections, The Adventures of Sherlock Holmes, was banned in the Soviet Union in 1929 for supposed occultism. This ban was later lifted. Russian actor Vasily Livanov later received an Order of the British Empire for his portrayal of Sherlock Holmes. Conan Doyle was friends for a time with the American magician Harry Houdini, who himself became a prominent opponent of the Spiritualist movement in the 1920s following the death of his beloved mother. Although Houdini insisted that Spiritualist mediums employed trickery (and consistently attempted to expose them as frauds),
foreign alphabets, as Greek, Hebrew, and Armenian, were used; each letter of the plaintext was replaced by the one that follows it; in the most advanced system, special signs substituted for letters. For almost a thousand years, from before 500 to 1400, the cryptology of Western civilization stagnated. During all these years, cryptology was acquiring a taint that lingers even today—the conviction in the minds of many people that cryptology is a black art, a form of occultism whose practitioner must, in William F. Friedman's apt phrase, "perforce commune daily with dark spirits to accomplish his feats of mental jiu-jitsu." In part it is a kind of guilt by association. From the early days of its existence, cryptology had served to obscure critical portions of writings dealing with the potent subject of magic—divinations, spells, curses, whatever conferred supernatural powers on its sorcerers. Another
annaabi.ee 
