Keeping Secrets Secret: Writing and Reading Ciphers

The only true prerequisites to these lectures are a curious mind and a
firm grasp of 'Please Excuse My Dear Aunt Sally' style arithmetic.
Along the way, we will present any advanced math that is needed. In
fact, an entire lecture is devoted to the math behind Cryptology.
This beautiful area of mathematics is called Number Theory, and has
been a fundamental area of mathematical research dating back at least
to the ancient Greeks.

This work was made possible through a grant from the National Science Foundation.