Crypto for everyone:
Crypto 101 is an introductory course on cryptography, freely available for programmers of all ages and skill levels.
Crypto 101: the presentation
Crypto 101 started as a presentation at PyCon 2013. It tries to go through all of the major dramatis personae of cryptography to make TLS work in 45 minutes. This book is the natural extension of that, with an extensive focus on breaking cryptography.