This book is the outgrowth of introductory cryptography courses for non-
math majors taught at Rutgers University and Williams College. It is a
pleasure to thank our colleagues and our students for many helpful conver-
sations that have greatly improved the exposition and guided the emphasis,
in particular Elliot Schrock (who helped write the Enigma chapter) and
Zane Martin and Qiao Zhang (who were the TAs for the 2013 iteration
at Williams College, Math 10: Lqwurgxfwlrq wr Fubswrjudskb, and who
helped guide the class in writing the solutions manual for teachers).
We are especially grateful to Wesley Pegden, who generously shared his
notes from versions he taught at Rutgers, and who provided numerous, de-
tailed comments. We also thank our editor, Ed Dunne, for all his help,
comments and advice throughout the project, Barbara Beeton and Jennifer
Sharp at the AMS for their excellent work in creating the final version of
the text, Teresa Levy for designing the cover, and the anonymous refer-
ees for their suggestions. We wish to thank a number of people who have
read and commented on the book, including especially Katrina Palmer at
Appalachian State University, Andrew Baxter at Penn State, and Robert
Wilson at Rutgers University. Several members of the NSA community
kindly shared general references as well as allowed one of the authors to use
an Enigma machine.
Some of this book was inspired by work done with the CCICADA Center
at Rutgers, a Department of Homeland Security University Center. Miller
was partially supported by NSF grants DMS0600848 and DMS0970067 dur-
ing the writing of this book, and gratefully acknowledges their support.