10 parts · 18 chapters
Cryptography and Security Foundations
Cryptography is a small set of primitives with precise guarantees, and most real failures come from using the right primitive the wrong way: a nonce reused, a hash used where a MAC was needed, a password hashed fast, a signature not checked. This course explains each primitive by what it guarantees, with costs measured on this machine.
Ten parts: hashes and MACs; symmetric ciphers and modes; public-key cryptography; digital signatures; key exchange; PKI and certificates; TLS from the bytes; password storage; common misuse; and threat modelling.
integrityHashes, MACs and HMAC, and which one each job needs.
confidentialityAES, ChaCha20, AEAD modes, nonces and keys.
public keyRSA, elliptic curves, signatures and key exchange.
trustCertificates, chains, PKI, and TLS put together.
passwordsArgon2id, scrypt, bcrypt, salts and peppers.
practiceMisuse patterns and STRIDE threat modelling.
00
Hashes and MACs
Hashes · MACs and HMAC
2 ch · ~12 min01Symmetric Ciphers and Modes
AEAD in practice · Keys: size, rotation and envelopes
2 ch · ~12 min02Public-Key Cryptography
Key pairs and the hard problems
1 ch · ~8 min03Digital Signatures
What signatures prove, and what they cost · Pitfalls
2 ch · ~12 min04Key Exchange
Agreeing on a secret in public
1 ch · ~8 min05PKI and Certificates
Chains of trust · Internal PKI and pinning
2 ch · ~12 min06TLS from the Bytes
Every primitive in one protocol · What TLS does not protect
2 ch · ~12 min07Password Storage
Slow on purpose · Beyond hashing
2 ch · ~12 min08Common Misuse
Six ways good primitives fail · Encoding is not encryption
2 ch · ~12 min09Threat Modelling
Four questions · A lightweight habit
2 ch · ~12 minBuilt on Discrete Maths and NetworkingNumber theory (course 25) explains why the maths works; Networking part 7 and Auth build on TLS, signatures and tokens.