Cryptography plays a vital role in modern digital communication systems. Cryptographic methods allow the encryption and decryption of messages sent across digital communication networks. In this free online course the learner is first introduced to ancient ciphers and how they were used. The vital role of randomness in cryptographic methods is then explained and the learner is taken through step-by-step examples. The role of key scientists such as John von Neuman is also explained. This course will be of great interest to all learners who would like to learn more about cryptography and the vital role it plays in today's digital communication networks.