How email works
How an email travels from one inbox to another, from the SMTP conversation between servers and the difference between envelope and header to MIME, mailbox access, and the SPF, DKIM and DMARC checks that fight forgery.
Topic
Security
How data and systems are protected, from the encryption that secures connections to the certificates that prove who is on the other end.
Articles
How OAuth and OpenID Connect work
How OAuth 2.0 lets an app act on your behalf without your password, from the four roles and the authorization code flow to PKCE, access and refresh tokens, JSON Web Tokens, sign-in with OpenID Connect, and today's security best practices.How passwords are stored
How websites store passwords so that a stolen database does not reveal them, from hash functions and salts to slow and memory-hard functions such as PBKDF2, scrypt and Argon2, and the defenses that go beyond the database.How public-key cryptography works
How two strangers can agree on a secret in public and prove who they are, explained with small worked examples of Diffie-Hellman and RSA, elliptic curves, digital signatures, key sizes and the move to post-quantum algorithms.How TLS works
How Transport Layer Security protects data on the internet, from the cryptographic building blocks and the TLS 1.3 handshake to certificates, the key schedule, resumption and what TLS cannot hide.