Certificates
What is inside an X.509 certificate, how you ask for one and how the CA checks you own the name.
8 chapters · 10 guides · 5 error pages
Topics
PKI topics
Pick a subject and see everything about it in one place: the chapters that explain it, the guides that do it, the error pages that fix it and the tools that check it.
Chains and trust stores
Why a client trusts a certificate: trust stores, intermediates, path validation and cross-signing.
5 chapters · 8 guides · 19 error pages
TLS and HTTPS
How HTTPS protects a connection: shared keys, key exchange, the TLS 1.3 handshake and server setup.
5 chapters · 8 guides · 6 error pages
Lifecycle and automation
Inventory, expiry, renewal and ACME, and how to get ready for much shorter certificate lifetimes.
3 chapters · 6 guides · 6 error pages
Revocation and transparency
Taking a certificate back (CRL, OCSP, stapling), Certificate Transparency logs and what famous failures taught.
4 chapters · 2 guides · 1 error page
Private PKI
Running a CA of your own: two-tier design, HSMs and key ceremonies, mutual TLS and device identity.
5 chapters · 8 guides · 4 error pages
Hashes and signatures
Hashes, digital signatures, and signing code and documents with timestamps.
4 chapters · 2 guides
Post-quantum cryptography
What a future quantum computer would break, the new standards, and hybrid key exchange in TLS today.
3 chapters · 2 guides
New to all of this?
Start with the ideas underneath every topic: shared secrets, key pairs, hashes and signatures. The crash course covers the whole map in about 90 minutes.