Cryptography
Five lessons covering the cryptographic primitives that secure everything on the internet.
Hashing (one-way functions that turn any data into a fixed-size fingerprint), symmetric encryption (encrypting and decrypting with the same key — AES), asymmetric encryption (public and private keys — how strangers communicate securely), digital signatures (proving who sent a message and that it wasn't tampered with), and key exchange (how two parties agree on a shared secret over an insecure channel — Diffie-Hellman).
These are the building blocks underneath TLS, HTTPS, certificates, password storage, git commits, JWTs, and code signing. The glossary defines every term. The FAQ answers common questions.
Lessons
1How Hashing Works — One-Way Functions and Digital Fingerprints2How Symmetric Encryption Works — One Key, Two Operations3How Asymmetric Encryption Works — Public Keys, Private Keys, and Trust4How Digital Signatures Work — Proving Authorship and Integrity5How Key Exchange Works — Sharing Secrets Over Insecure Channels6Cryptography FAQ
Glossary
What is a Hash FunctionWhat is SHA-256What is AESWhat is a Block CipherWhat is a Public KeyWhat is a Private KeyWhat is RSAWhat is Elliptic Curve CryptographyWhat is a Digital SignatureWhat is Diffie-HellmanWhat is a SaltWhat is a NonceWhat is HMACWhat is a Certificate AuthorityWhat is bcryptWhat is an Initialization Vector