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.
21 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 · 10 min→then 5 modules · 80 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 · 16 min→then 6 modules · 96 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 · 16 min→then 14 modules · 267 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 · 24 min→then 10 modules · 171 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 · 16 min→then 7 modules · 106 minComprehensive, no filteringResearcher / AcademicOpen the full catalog. Every module, in order, with no persona filtering.
First win — Start at the very beginning · 20 min→then 21 modules · 356 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 · 16 min→then 8 modules · 165 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.
Playground
Real cryptography running in your browser — encrypt, sign, and verify with the Web Crypto API.
Assess
Eight quick questions about what you run today, mapped to a prioritized reading list.