Free online courseModern Cryptography for Beginners: Encryption, Hashing, Signatures and Secure Computation

Course Description

Modern systems rely on cryptography every time you log in, send a message, pay online, or establish a secure connection. This course gives beginners a clear path into modern cryptography by focusing on the ideas that actually drive security in practice: rigorous threat models, precise definitions, and the reasoning that links an algorithm to the protection it promises. Instead of treating crypto as magic, you learn how to think like a security engineer and how to measure what an attacker can and cannot do.

You start with the purpose of cryptography and why the notion of an adversary sits at the center of everything. With that mindset, the course connects real-world secure channels like TLS to their essential building blocks, explaining why key exchange must be authenticated and what can go wrong when it is not. Through simple motivating stories, you develop intuition for protocol design, including fairness and bias prevention, before moving into the core primitives that power modern security.

From there, you build a practical foundation in symmetric cryptography: block ciphers, why standards like DES led to AES, and how security is defined through games such as key recovery and pseudorandomness. You see why shortcuts like Double DES fail against classic attacks, and how birthday-style effects shape real security limits. With that groundwork, you learn encryption modes and what it really means to be secure against chosen-plaintext attacks, understanding why deterministic encryption leaks patterns and how modern modes prevent it.

The course then expands your toolbox with hash functions, message authentication, and authenticated encryption, emphasizing how privacy and integrity must work together. You move into the number theory behind public-key cryptography, then study RSA and Diffie–Hellman through the lens of formal security goals, including why chosen-ciphertext security requires carefully restricting decryption access. Digital signatures and Schnorr-style reasoning add authenticity and non-repudiation concepts, and the course ties them to real deployments with public-key infrastructure and certificates.

Finally, you explore advanced but increasingly relevant ideas: identity-based encryption, commitment schemes, homomorphic encryption limits, and secure computation from two-party to multi-party settings using secret sharing. By the end, you will be able to read crypto discussions with confidence, understand why protocols are constructed the way they are, and make better security decisions in engineering and cybersecurity contexts.