Ancient Cryptography: Security and Information Theory

This lecture covers the evolution of cryptography from pre-modern industrial techniques to modern information theory. Topics include the security implications of key length, exhaustive search on 128-bit keys, the laws of modern cryptography, and the Vernam cipher. The instructor discusses perfect secrecy, the Shannon encryption model, and the implications of Shannon's theorems on key length and plaintext distribution. The lecture concludes with a comparison between information theory and complexity theory in the context of cryptography.