When working on the proposed book, the author set himself several tasks. Among them were acquaintance of readers both with the history of the emergence and development of codes and ciphers, and with the most interesting and noticeable events from the history of cryptology. The author also tried to talk about the most difficult ciphers and codes for his time that were invented in the entire centuries-old history of mankind, as well as the geniuses who were able to unravel them.