competition-oauth-oidc-chain（competition OAuth oidc chain 安全）

Competition OAuth OIDC Chain

Use this skill only as a downstream specialization after $ctf-sandbox-orchestrator is already active and has established sandbox assumptions, node ownership, and evidence priorities. If that has not happened yet, return to $ctf-sandbox-orchestrator first.

Use this skill when the hard part is proving how an OAuth or OIDC flow is shaped, exchanged, and ultimately accepted.

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Quick Start

1. Map the auth chain in order: entry route, redirect, authorize request, callback, token exchange, refresh, and final accepting service.
2. Record scopes, state, nonce, PKCE material, redirect URIs, and claim-bearing tokens before mutating anything.
3. Separate token possession from actual identity acceptance.
4. Keep browser-visible redirects and backend-visible token exchange in one compact chain.
5. Reproduce the smallest redirect-to-acceptance flow that proves the decisive identity edge.

Workflow

1. Map The Redirect And Token Path

• Record issuer, client ID, redirect URI, authorize parameters, callback parameters, token endpoint, and refresh path.
• Note which values are user-controlled, derived, cached, or validated: state, nonce, PKCE verifier, audience, scope, or prompt.
• Keep browser redirects, server-side exchanges, and resulting session state tied together.

2. Prove Token-To-Identity Acceptance

• Show how code, ID token, access token, or refresh token turns into app session, claims mapping, tenant selection, or accepted privilege.
• Record token claims, expiration, audience, subject, scopes, and the exact accepting app or backend edge.
• Distinguish UI login success from backend authorization success.

3. Reduce To The Decisive OAuth Chain

• Compress the result to the smallest sequence: entry request -> redirect -> callback -> token or claim acceptance -> resulting capability.
• Keep one canonical good flow and one minimal mutated flow if a parameter change matters.
• If the task broadens into generic web routing or storage behavior outside the auth chain, switch back to the broader web-runtime skill.

Read This Reference

• Load references/oauth-oidc-chain.md for the redirect checklist, token checklist, and evidence packaging.
• If the hard part is JWT header parsing, claim normalization, key lookup, or token validation confusion after issuance, prefer $competition-jwt-claim-confusion.

What To Preserve

• Redirect URIs, parameters, codes, token claims, scopes, and the accepting service or callback
• The exact point where claims or tokens become accepted app identity
• One minimal replayable redirect-to-acceptance sequence