Ebook: Codes and Secret Writing

The definitive work on codes and ciphers. Explains how to make and break several kinds of codes, how to use secret languages, and how to make invisible inks. Zim is the most comprehensive text on codes and secret writing, containing instructions on most common methods of encrypting messages. The book gives a brief history of codes, then goes on to explain the difference between codes and ciphers, writing with invisible ink, and using code wheels or other equipment. An abridged scholastic edition. Printed in USA. ISBN 0-590-02505-8.