I first read this book when I was very young in a scholastic bound edition. It has some very, very simple codes and cyphers explained very easily with simple, amusing illustrations. Basic substitutions, "invisible" ink, and the like. You won't find discussion of PGP, TripleDES or RSA Encryption here; the book is aimed at your precocious 7-10 year old. One of the codes in here I have used for nearly twenty years to keep my notes private, and I can write it as fast as english! Looking back at it, the book is a little silly, but I remember it as a great favorite. Take this review with a grain of salt- the Author, John Lawrence Peterson, is my grandfather. @--William Lawrence Peterson
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