Codes and Ciphers

Sometimes people want to keep their communications secret. Others, on the other hand, always want to break into other people's secrecy. This course will be very hands-on and will tell us how to keep our information secret, and how to break the secrecy of others. We will study some of the most important codes used throughout the history, how they were broken, and their historical significance. This will include the Caesar's wheel, schemes of European courts of early modern age, and the Enigma machine from World War II. This year, we will also learn how modern computers keep information secret. We will get to discuss a range of topics from error-correction codes that can detect if your message has been tampered with, to key-exchange protocols that complete strangers can use to start a secure communication channel without having to meet each other. Though it may sound unintuitive at first, we will also learn how you can encode a message using one key and how your friend can decode it using a completely different key.