Classical cryptography, explained

Classical Crypto Today

The cryptography running the internet right now: what RSA, AES, SHA-2 and TLS actually do, before you plan for what comes next.

28 modules · growing catalog

Where do you want to start?

Pick a section. Learn lets you filter the catalog by role if you want a tailored track.

Every topic on the site in plain words, with a first stop for each.

The full module catalog — symmetric crypto, public-key crypto, and how TLS combines them.

How those primitives combine in production — envelope encryption, PKI, OAuth2/OIDC/SAML.

NIST, the IETF, ISO/IEC, and OASIS — who writes the specs, and what each has actually published.

Real cryptography running in your browser — encrypt, sign, and verify with the Web Crypto API.

Break real ciphers and implementation mistakes yourself, and recover the flag as proof.

Every knowledge check on the site in one place — one per Learn module, Use Case, and Standards body.

Eight quick questions about what you run today, mapped to a prioritized reading list.