This course provides an introduction to cryptography, from its historical context to its applications. Students learn how fundamental mathematical concepts are the bases of cryptographic algorithms. Students learn about the Enigma machine and Navajo code, the implementation and cryptanalysis of classical ciphers, such as substitution, transposition, shift, affine, Vigenère and Hill. After introducing elementary methods and techniques, the class fully develops the Enigma cipher machine and Navajo code used during World War II. Students see mathematics in cryptology through monoalphabetic, polyalphabetic and block ciphers. The course includes a focus on public-key cryptography, and the textbook describes RSA ciphers, the Diffie–Hellman key exchange, and ElGamal ciphers. If time allows, students may also explore current U.S. federal cryptographic standards, such as the AES, and explore how to authenticate messages via digital signatures, hash functions and certificates. Algebra II is a prerequisite for this course. (Semester, .50 credit)