Codes, Ciphers and Secret Writing (Dover Children's Activity Books)

"A fascinating, challenging book." ― A.L.A. Booklist
Learn to use the most important codes and methods of secret communication in use since ancient times. Cipher and decipher codes used by spies. Explore the famous codes that changed the fate of nations and political leaders. And enjoy hours of fun experimenting with cryptography ― the science of secret writing.
Beginning with simple letter substitutions and transposition ciphers, world-famous science writer Martin Gardner explains how to break complicated polyalphabetical ciphers and codes worked with grids, squares, triangles, and charts. You'll learn codes that are keyed to typewriters and telephone dials . . . even codes that use playing cards, knots, and swizzle sticks. Experiment with invisible writing ― inks that glow in black light and turn red under heat ― and explore the possibilities of sending messages through outer space to unknown worlds.
Using this book, you can solve the historically famous Playfair Cipher used by Australia in World War II, the Pigpen Cipher used by Confederate soldiers during the Civil War, Thomas Jefferson's Wheel Cipher, the Beaufort system used by the British Royal Navy, codes devised by authors for heroes in literature ― Sherlock Holmes, Captain Kidd, and the Shadow. And you will enjoy experimenting with bizarre methods of message sending ― the Dot Code, Knot Code, Swizzle Code, and more.
Young cryptanalysts, cipher fans, and puzzlists of all ages will find hours of intrigue and challenge in Codes, Ciphers and Secret Writing.

"A stimulating must for the intermediate cryptographer." ― The Kirkus Reviews