Ciphers and Codes

Résumé du livre

Open this book to learn about ciphers and codes -- the tools used to keep a message secret. See how ciphers were used by the patriots in the American Revolutionary War. Find out how to make your own cipher. In this book, you will: discover how flag signals and smoke signals work, see how computers use ciphers and codes today, find out how you can break a cipher without a key. Book jacket.