Lesson 5 of 12 · 7 min read
OpenID Connect and ID Tokens
OpenID Connect is an identity layer on top of OAuth 2.0. Alongside an access token for APIs, it returns an ID token: a signed JWT stating who the user is, who issued the statement, which client it is for, and when it expires. The client validates it and creates its own session. Confusing ID tokens with access tokens, or skipping audience and nonce checks, are the classic mistakes.
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Practise it as an interviewer asks it
What is the difference between authentication and authorization, and where does each usually fail?How does the OAuth 2.0 authorization code flow with PKCE work, and what attacks does each part stop?What is the difference between OpenID Connect and OAuth, and between an ID token and an access token?Server sessions or bearer tokens: how do you choose, and how do you secure each?What security risks does the Model Context Protocol (MCP) introduce?RBAC, ABAC or relationship-based access control: design authorization for a document product.