Modern Applied Cryptography: AES, RSA, ECC, Hashing and Post-Quantum Basics by Christof Paar

About this course

Build practical, up-to-date cryptography intuition by learning how modern security systems protect data in apps, networks, and cloud services. This free online course connects the math you need with the real mechanisms used in production: symmetric encryption for fast bulk protection, public-key cryptography for key exchange and authentication, and hashing for integrity and secure signatures.

You will start with core concepts that explain what cryptography can and cannot guarantee, then develop the foundations that make today’s algorithms work, such as modular arithmetic, number theory, and efficient exponentiation. From there, you will progress through classic and modern constructions, gaining a clear understanding of why certain designs are considered secure, how attacks influence parameter choices, and how implementation details can affect outcomes.

The course explains how stream ciphers generate keystream, what can go wrong when randomness is weak, and why reusing secrets can break confidentiality. You will also see how block ciphers evolved from DES to AES, and how modes of operation change security in real deployments, including why some modes leak patterns and why others require careful handling of nonces or IVs.

On the public-key side, you will learn the logic behind RSA and Diffie–Hellman, then move to elliptic-curve cryptography to understand why it delivers strong security with much smaller key sizes. You will also connect encryption and key exchange to digital signatures, clarifying the difference between authenticity, integrity, and non-repudiation, and why MACs and signatures serve different security goals.

Hash functions and modern standards such as SHA-1 and SHA-3 are covered with a focus on practical use: pre-hashing long messages before signing, preventing forgery, and reasoning about collision resistance. Finally, you will get a grounded introduction to post-quantum basics, learning how large-scale quantum computers change the threat model for RSA and ECC compared to symmetric cryptography, and how hash-based signatures like Merkle schemes fit into a future-ready security toolbox.

Throughout, short questions help you test understanding of the key ideas and typical pitfalls, making the course a strong fit for developers, security learners, and anyone preparing for work involving encryption, secure protocols, certificates, or PKI. By the end, you will be able to read and discuss cryptographic designs with confidence, choose safer options in common scenarios, and better understand why modern systems are built the way they are.