Cryptography: Ancient Techniques to Modern Systems

This lecture delves into the prehistory of cryptography, starting with ancient techniques used by Spartans and Caesar, such as transposition and substitution. The instructor explains the Enigma machine, its design, and how it was broken during World War II. The lecture covers the Kirchhoff's principle, emphasizing that security should not rely on the secrecy of the crypto system. It also discusses the scalability issue in cryptography, highlighting the need for public key cryptography to reduce the number of keys in mass communication networks. The Moore's Law is explained, showing the exponential growth in CPU speed over time and its impact on cryptographic computations. The lecture concludes with a thought experiment on breaking a 128-bit key and the implications of technological advancements.