We all know that security is hard, and that math is hard, but what happens when you put them together? Cryptography is an increasingly essential tool for building secure systems, but also a perilous minefield where any number of mistakes can lead to insecure systems. This talk will take you step-by-step through the difficulties of building secure cryptosystems on top of Ruby's existing OpenSSL bindings and contrast that with RbNaCl, a next generation Ruby cryptography library specifically designed to be more mistake-proof and put cryptography "on Rails". Attendees will hopefully learn that the best approaches to cryptography rest in making systems simple, straightforward, and boring... in a good way.