01. Overview & Crypto Basics
The problem certificates solve and the underlying symmetric/asymmetric cryptography, hashing, and digital signatures
02. X.509 Structure & PKI
X.509 certificate fields, encoding/extensions, PKI components (CA/RA/CSR), and the trust model
03. Root & Chain of Trust
Roles of root/intermediate/leaf certificates, chain verification, the trust store, and root renewal/rollover
04. Auth Logic (TLS)
How certificates are actually verified in the TLS handshake, server authentication and key exchange, and mTLS
05. Lifecycle & Renewal
From issuance to renewal (shorter lifespans, ACME automation) and revocation (CRL/OCSP/OCSP stapling) and CT logs
06. Practice (OpenSSL)
Generating keys/CSRs, inspecting/debugging certificates, format conversion, full-chain deployment, expiry monitoring, and private-CA operation with OpenSSL