An interactive guide to modern cryptography. From hash functions to post-quantum algorithms, the essential primitives and protocols that secure our digital world.
Primitives are the building blocks. Protocols combine them into secure systems. Applications show them in the wild.
The Ingredients of Cryptography
Setting the stage: why cryptography matters and what you'll learn.
Digital fingerprints, keyed authentication, and why hash(key || message) is broken.
Where keys, nonces, and IVs come from. The foundation everything else depends on.
Block ciphers, modes of operation, and authenticated encryption. From AES to AES-GCM.
Groups, finite fields, and elliptic curves. The algebra behind public-key cryptography.
Establishing shared secrets over insecure channels.
Asymmetric encryption, hybrid schemes, and digital signatures.
The Recipes of Cryptography
Certificates, TLS, and the protocols that secure the internet.
Password storage, TOTP, passkeys, and proving who you are.
Side channels, padding oracles, key management failures, and real-world disasters.
Cryptography in the Wild