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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..even codes that use playing cards, knots and swizzle sticks. Experiment with invisible writing - inks that glow in blacklight and turn red under heat - and explore the possibilities of sending messages through outer space to unknown worlds.
Unknown Binding
First published January 1, 1972