cybersecurity / cryptography
Cryptography, Free
The math that keeps secrets — encryption, hashing, and the protocols behind every secure connection. Learn the theory from a landmark course, then truly understand it by breaking bad crypto yourself. All resources free and current.
Cryptography underpins all of security — TLS, password storage, digital signatures, cryptocurrencies. It's famously easy to get subtly, catastrophically wrong, which is why the best way to learn it is a mix of solid theory and hands-on practice attacking broken implementations. Start with a foundational course or the approachable "Crypto 101" book, then sharpen your instincts on the Cryptopals challenges.
01 · LEARN THE THEORY
Foundations
The concepts, from a landmark course and a free book.
- Cryptography I — Stanford (Dan Boneh) ↗The definitive university cryptography course, taught by a leading researcher — symmetric and public-key crypto from the ground up. Free to audit.coursera.org
- Crypto 101 (free book) ↗A free, approachable introduction to cryptography for programmers — no heavy math prerequisites, plenty of practical intuition.crypto101.io
02 · BREAK IT TO LEARN IT
Hands-on challenges
The fastest way to really understand crypto: attack it.