Introduction to Cryptography

Learning Objectives

• Apply Shannon's properties of Confusion and Diffusion to modern ciphers.
• Understand the implications of Kerckhoffs's Principle in cryptographic engineering.
• Analyze standard cryptanalysis attack models (CPA, CCA).
• Master mathematical foundations: Modular Arithmetic and Prime Number Theory.
• Distinguish between PRNGs, CSPRNGs, and the role of entropy in key generation.

Seminar Structure (3 Hours)

• Shannon's Confusion & Diffusion
• Kerckhoffs's Principle & Attack Models
• Task 1: Cryptanalysis Simulation

• Modular Arithmetic & Prime Theory
• Entropy, PRNGs, and CSPRNGs
• Task 2: Entropy and Randomness Audit

Entropy and Randomness

A cipher is only as strong as the randomness of its key.

• PRNG (Pseudo-Random Number Generator): Deterministic algorithms. Predictable. Fine for simulations, catastrophic for cryptography.
• CSPRNG (Cryptographically Secure PRNG): Possesses the Next-Bit Test property. Unpredictable even if internal state is partially known.