Before noon
Breaking Historical Ciphers
The use of encryption for the protection of communication during war time is of critical importance – and has been for thousands of years. In the 19th century, the United States was embroiled in a Civil War with both the South, the Confederacy, using a well-known and classical encryption method of Italian and French origin and the North, the Union, using a new approach.
In this talk, we consider several historical ciphers – and then we look at two previously undeciphered examples from the US Civil War – and we break them.
Learning outcomes
- Understand the fundamentals of both monoalphabetic and polyalphabetic ciphers.
- Understand the differences between ciphers and codes.
- Identify and exploit weaknesses in both monoalphabetic and polyalphabetic ciphers.
After noon
Measurements of Uncertainty and the Good, the Bad and the Ugly of Randomness
In Computer Science, information is a measure of not what you do know but what you do not know. The higher the information content, the entropy, the more random the data, the outcome of an experiment, or a variable. Randomness is often desirable, especially in cryptography. Low entropy can be very bad.
We will experiment and measure uncertainty and entropy in language, in games and in the music of Justin Bieber. This leads to fundamentals of passwords, data storage and data security, and then to formerly classified United States efforts breaking Soviet secret messages of the 1940s and 1950s and the unmasking of spies.
Learning outcomes
- Understand entropy of a random variable and calculate examples in data, music and language.
- Understand passwords and cryptographic keys for symmetric encryption, especially password-based encryption.
- Experiment with efficient data encodings and understand compression as data storage, including one application to cryptanalysis.