Classical cryptography, explained and grounded
The cryptography running the internet, right now.
RSA. ECC. Diffie-Hellman. AES. SHA-2. TLS. This is the “classical” cryptography that post-quantum algorithms are set to replace — and almost none of it is going anywhere overnight. Understand what it actually does before you plan around what comes next.
26 modules · growing catalog
Who's asking?
Pick the closest fit and we'll lead with what's most useful to you. You'll still see everything — nothing gets hidden, and you can change this on any page.
Your board is asking about the PQC migration. Before you can answer, you need to know what "classic" crypto your organisation actually depends on today.
First win — See what's actually at risk · 12 min→then 5 modules · 120 minObligations, inventory & evidence focusGRC / Risk & ComplianceAuditors want a cryptographic bill of materials. Know which algorithms are in scope before you can attest to anything.
First win — Map the algorithms you must inventory · 24 min→then 6 modules · 117 minImplementation & protocol focusDeveloper / EngineerRSA, AES, ECDSA and SHA-2 are already in every library you import. Understand what they actually do before you touch a crypto API.
First win — See a real handshake, step by step · 24 min→then 17 modules · 471 minSystem & infrastructure focusSecurity ArchitectEvery PKI, VPN and TLS terminator you've designed rests on the same handful of primitives. Get the mental model right before you redesign anything.
First win — Trace trust from key exchange to signature · 40 min→then 13 modules · 300 minDeploy & operate focusIT Ops / DevOpsCertificates, cipher suites, key sizes — the settings you configure every day encode decades of cryptographic design. Know what they mean.
First win — Understand what a cipher suite actually says · 24 min→then 9 modules · 186 minComprehensive, no filteringResearcher / AcademicOpen the full catalog. Every module, in order, with no persona filtering.
First win — Start at the very beginning · 28 min→then 26 modules · 612 minNew to cryptographyCurious ExplorerYour browser's padlock icon runs on math you use every day without seeing. Here's what's actually happening behind it.
First win — What happens when you visit a website · 24 min→then 9 modules · 271 minExplore
Every topic on the site in plain words, with a first stop for each.
Learn
The full module catalog — symmetric crypto, public-key crypto, and how TLS combines them.
Use Cases
How those primitives combine in production — envelope encryption, PKI, OAuth2/OIDC/SAML.
Standards
NIST, the IETF, ISO/IEC, and OASIS — who writes the specs, and what each has actually published.
Playground
Real cryptography running in your browser — encrypt, sign, and verify with the Web Crypto API.
Challenges
Break real ciphers and implementation mistakes yourself, and recover the flag as proof.
Quizzes
Every knowledge check on the site in one place — one per Learn module, Use Case, and Standards body.
Assess
Eight quick questions about what you run today, mapped to a prioritized reading list.