If you find any typos, please email them to [email protected]. (Apologies in advance if I haven't posted your errata submission yet or failed to give credit. Please email me to correct this.)

Chapter 16 - Programming the Simple Substitution Cipher

On pages 209 and 212, line 14 of the program should change from if keyIsValid(myKey): to if not keyIsValid(myKey): (Thanks to Hamid R.)