Editing OAuth 2.0 (section)

== Analyzing (Break Down / Analysis) 🔬 ==
=== Comparative analysis ===
* Versus API keys: OAuth provides scoped, revocable, user-consented access.
* Versus SAML: OAuth is lightweight and optimized for APIs rather than enterprise identity federation.
* Historically replaced OAuth 1.0’s complex signature system with simpler bearer tokens.

=== Structural insights ===
* Authorization Code, Client Credentials, Device Code, Refresh Token flows form the core architecture.
* Tokens carry scopes representing permitted operations.
* Separation of authorization vs resource servers allows distributed security design.

=== Failure modes & root causes ===
* Misconfigured redirect URIs → open redirect vulnerabilities.
* Storing tokens insecurely → token theft.
* Failing to use PKCE in public clients → authorization code interception.

=== Troubleshooting & observability ===
* Inspect access token expiry, issuer, and scope.
* Log authorization errors such as `invalid_grant` or `invalid_scope`.
* Monitor token issuance rates and misuse patterns.

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