Communicating sensitive or secretive information has been a human endeavor for centuries and so is the quest to decode such information. In this course, we will study cryptology which encompasses both cryptography, the process of encoding information and cryptanalysis, the process of independently decoding information, without the help of the people or system that encoded it. This course will cover ancient ciphers, such as the Caesar shift cipher, mechanical encryption methods, such as the Enigma machine, and modern public-key encryption methods, such as RSA encryption. Each cryptosystem will be introduced using the historical context under which the system was first developed. Almost all cryptology methods rely on the mathematics of number theory, the study of the positive whole numbers. This course will focus on the specific number theory concepts required to understand each cryptosystem including the Euclidean algorithm and modular arithmetic, matrix multiplication, permutations and the symmetric group, non-decimal arithmetic, primes and factorization.