JWT, OAuth 2.1 & OpenID Connect (OIDC) — Principal Architecture Deep Dive
Under-the-hood engineering guide to JOSE (JWS/JWE/JWKS), OAuth 2.0 vs OAuth 2.1, PKCE S256 cryptography, OpenID Connect ID Token mechanics, Phantom Token pattern, DPoP (RFC 9449), Token Exchange (RFC 8693), and Senior/Staff interview playbooks.