Het ontwerpen van een OAuth 2.0-authenticatie- en autorisatiestroom waarbij scopes automatisch worden ingetrokken op basis van veranderende gebruikerscontext of beveiligingssignalen vereist een dynamische en flexibele aanpak. Hieronder vind je een gedetailleerde aanpak, inclusief regels voor scope herroeping en best practices. **1. Architectuur en Conceptuele Benadering** - **Dynamic Scope Management:** Gebruik een centraal autorisatie- en policy-managementsysteem dat in staat is om op basis van gebruikerscontext en beveiligingssignalen te bepalen of een scope geldig is of ingetrokken moet worden. - **Token Intrekking en Vernieuwing:** Implementeer mechanismen voor het intrekken van tokens of het dynamisch aanpassen van toegangsrechten zonder dat de gebruiker opnieuw moet inloggen (bijvoorbeeld via token introspectie en scope herwaardering). **2. Regels voor Scope Herroeping op Basis van Context** a) **Locatie (EU, Kantooruren):** - Regels kunnen bijvoorbeeld bepalen dat bepaalde gevoelige scopes alleen geldig zijn wanneer de gebruiker zich binnen de EU bevindt en tijdens kantooruren. - Buiten deze tijden/locaties wordt de scope automatisch ingetrokken of niet uitgegeven. b) **Apparaatstatus (Nieuw apparaat):** - Bij detectie van een nieuw apparaat (bijvoorbeeld via device fingerprinting of IP-adres analyse) wordt een beveiligingsregel geactiveerd die de bestaande scopes intrekt totdat extra verificatie plaatsvindt. c) **Risicovolle Activiteiten:** - Detectie van verdachte activiteiten (bijvoorbeeld ongebruikelijke toegangspatronen, brute-force pogingen) kan leiden tot het intrekken van gevoelige scopes of het herbevestigen van gebruikersauthenticatie. **3. Implementatie van Scope Herroeping** - **Gebruik van Claims en Contextgegevens:** - Voeg gebruikerscontext en beveiligingssignalen toe als claims in het access token of via dynamische verificatie tijdens API-aanroepen. - **Token Introspectie:** - Laat API's regelmatig token introspectie uitvoeren om te controleren of de token nog geldig is en of de scope nog relevant op basis van actuele context. - **Scope Policy Enforcement:** - Integreer een policy engine (bijvoorbeeld OPA - Open Policy Agent) dat op basis van de context bepaalt of een scope mag worden gebruikt. - Bijvoorbeeld: ``` if locatie != 'EU' of toegangstijd outside 'kantooruren' then revoke scope 'gevoelige-data' ``` - **Revoke API:** - Bied een endpoint aan om tokens of scopes actief in te trekken op basis van beveiligingssignalen. - Bijvoorbeeld: bij detectie van nieuw apparaat of verdachte activiteit wordt de bestaande token ingetrokken, en een nieuwe scope-toestemming wordt gevraagd. - **Gebruikersherificatie:** - Vereis dat gebruikers opnieuw authenticeren of extra verificatie doorlopen voordat gevoelige scopes worden heruitgegeven. **4. Best Practices** - **Minimalistische Scope Toekenning:** - Ken alleen de minimaal noodzakelijke scopes toe en herzie deze regelmatig. - **Contextbewuste Tokens:** - Overweeg het gebruik van short-lived tokens die regelmatig vernieuwd worden op basis van contextveranderingen. - **Logging en Monitoring:** - Log automatisch scope-inname en intrekkingen, en monitor onregelmatigheden. - **Automatisering en Policy-Driven Approach:** - Gebruik een policy engine dat contextparameters gebruikt voor real-time beslissingen over scope-toekenning en -intrekking. - **Gebruikerscommunicatie:** - Informeer gebruikers wanneer hun scopes worden ingetrokken en bied makkelijke manieren om opnieuw toestemming te geven indien nodig. **5. Samenvatting** - Definieer duidelijke regels gebaseerd op locatie, apparaat, en activiteiten. - Gebruik dynamische tokens, token introspectie en policy engines om scope- en tokenbeheer flexibel te houden. - Integreer automatische intrekkingsmechanismen bij beveiligingssignalen zoals nieuw apparaat of verdachte activiteit. - Volg best practices zoals minimale scope toe te kennen, korte token levensduur, en regelmatige herbeoordeling van toegangsrechten. Met deze aanpak creëer je een veilige, flexibele OAuth 2.0-implementatie die zich dynamisch aanpast aan veranderende gebruikerscontext en beveiligingssignalen.

Of course. Here is a design for an OAuth 2.0 flow with context-based scope revocation, tailored to your requirements, along with implementation best practices. ### High-Level System Design This system extends the standard OAuth 2.0 flow with a real-time authorization and monitoring layer. The key is to treat the issued access token not as a static "all-access pass" but as a **lease** that can be re-evaluated and partially revoked at any moment. The core components are: 1. **Authorization Server (AS):** Enhanced to evaluate context during token issuance and host the revocation logic. 2. **Resource Server (RS):** Your API endpoints. Enhanced to validate tokens not just for signature and expiry, but also for valid scopes in the current context. 3. **Policy Decision Point (PDP):** A logical component (often part of the AS) that makes real-time decisions on scope validity based on context and security rules. 4. **Policy Enforcement Point (PEP):** A logical component (part of the RS) that intercepts API calls and consults the PDP. 5. **Context / Risk Engine:** A service that aggregates and analyzes user context (location, device fingerprint, time, behavior) in real-time. --- ### The Enhanced OAuth 2.0 Flow with Context-Based Revocation The process involves two main phases: Initial Authorization and Real-Time Enforcement. #### Phase 1: Initial Token Issuance 1. **User Authentication & Consent:** The user authenticates with the Authorization Server and consents to the requested scopes (`profile.read`, `data.write`, etc.). 2. **Context Collection:** The AS collects initial context *at the time of login*: * **Device Fingerprint:** Creates a hash of device attributes (user agent, OS, screen resolution, installed fonts – using a library like `FingerprintJS`). * **IP Address:** To derive approximate location (e.g., EU, as per your context). * **Timestamp:** To confirm access is during business hours. 3. **Policy Check (Initial):** The AS runs its rules against this initial context. * *Rule: "Is the device new?"* The AS checks the device fingerprint against a history of the user's known devices. If it's new, the rule is triggered. * *Rule: "Is the location outside the EU?"* The IP is geolocated. Since the user is in the EU, this rule passes. * *Rule: "Is it outside business hours?"* The timestamp is checked. Since it's business hours, this rule passes. 4. **Token Issuance with Claims:** The AS issues an access token. Crucially, this token includes **contextual claims** in its JWT payload (if using JWT-based tokens): ```json { "iss": "https://auth.yourcompany.com", "sub": "1234567890", "aud": "https://api.yourcompany.com", "exp": 1735689600, "scope": "profile.read data.write", "device_fp": "a1b2c3d4e5f6h7...", // Hashed device fingerprint "auth_time": 1735689000, "ip_addr": "192.0.2.100" } ``` *Due to the "new device" rule being triggered, the AS could have already chosen to omit more sensitive scopes (e.g., `data.write`) from the token.* #### Phase 2: Real-Time API Access & Enforcement This is where continuous evaluation happens. 1. **API Request:** The client application calls your API (the Resource Server), presenting the access token. 2. **Token Introspection (PEP calls PDP):** The Resource Server doesn't trust the token's scopes blindly. It calls a `/introspect` endpoint on the Authorization Server (the PDP), passing: * The access token. * **Current real-time context:** The current IP address of the request, timestamp, and any other relevant signals. ``` POST /oauth/introspect Headers: {Authorization: Basic RS_credentials} Body: { token: "abc123jwt...", client_ip: "192.0.2.100", // Might be the same or different if user moved timestamp: 1735689300 } ``` 3. **Real-Time Policy Evaluation (PDP):** The Authorization Server: * Validates the token's signature and expiry. * **Fetches the latest risk signals** from the Context Engine (e.g., "Has this user's account had a failed login attempt from Asia in the last 5 minutes?"). * **Re-runs all revocation rules** using a combination of the *original token claims* and the *current real-time context*. 4. **Introspection Response:** The AS returns an introspection response indicating which scopes are **currently** valid. **Normal Response (context unchanged):** ```json { "active": true, "scope": "profile.read data.write", "sub": "1234567890" } ``` **Response after Revocation (e.g., user now on a new device):** ```json { "active": true, // The token itself is still technically valid "scope": "profile.read", // 'data.write' scope has been revoked! "sub": "1234567890", "reason": "access_from_new_device" } ``` 5. **API Execution:** The Resource Server enforces the list of scopes returned by the introspection endpoint. If the requested API endpoint requires `data.write` but the current valid scopes only include `profile.read`, it returns a `403 Forbidden` error. --- ### Defining Revocation Rules (Based on Your Requirements) Rules are defined as logic in your Policy Decision Point. They should be easily configurable. Here are examples: 1. **Rule: Revoke on New Device** * **Condition:** `current_device_fingerprint NOT IN user.known_devices` * **Action:** `revoke_scope("data.write")` // Revoke high-privilege scopes * **Implementation:** Maintain a database of hashed device fingerprints for each user. On first seen device, trigger action. 2. **Rule: Revoke on Location Change (e.g., EU to non-EU)** * **Condition:** `geolocate(original_token.ip_addr).country != geolocate(current_request.ip_addr).country` * **Action:** `revoke_scope("data.write")` or even `revoke_all_scopes()` * **Implementation:** Use a IP geolocation API or local database like MaxMind. 3. **Rule: Revoke on Access Outside Business Hours** * **Condition:** `current_time < 09:00 UTC OR current_time > 17:00 UTC` * **Action:** `revoke_scope("data.write")` // Keep read-only access * **Implementation:** Use UTC and consider the user's home timezone stored in their profile. 4. **Rule: Revoke on Risky Activity (from Risk Engine)** * **Condition:** `risk_engine.get_user_risk_score(user_id) > THRESHOLD` * **Action:** `revoke_all_scopes()` // Full logout * **Implementation:** Integrate with a risk engine that signals based on brute force attempts, threat intelligence feeds, etc. --- ### Best Practices for Implementation 1. **Use JWTs for Tokens:** JSON Web Tokens are ideal because they can be statically encoded with initial context claims (like `device_fp`), which are vital for the rules engine to compare against the current context. 2. **Token Introspection is Key:** Do not validate scopes only by decoding the JWT on the RS. The JWT's scopes represent the *maximum consented scope*. You **must** use the introspection flow to get the *current valid scope*. The OAuth 2.0 Token Introspection RFC (7662) is your friend. 3. **Keep Introspection Fast:** To avoid latency, cache introspection results for a very short period (e.g., 5-30 seconds) based on the required security level. Use a cache key that includes the token and the major context elements (e.g., IP prefix). 4. **Graceful Degradation:** When revoking scopes, don't always break the user experience. Prefer revoking high-risk scopes (e.g., `write`, `delete`, `admin`) first, while allowing low-risk scopes (e.g., `read`) to remain. This balances security and usability. 5. **Notify the User:** If a critical scope is revoked due to security policy (e.g., "We noticed a login from a new device, so write access has been temporarily disabled"), inform the user through a UI message, email, or push notification. This is transparent and builds trust. 6. **Secure Device Fingerprinting:** Hash device fingerprints on the client side before sending them to your backend to avoid handling raw PII. Treat the hashed fingerprint as a sensitive credential itself. 7. **Implement a Dashboard:** Allow users to view and manage their trusted devices and active sessions, empowering them to self-remediate if they receive a false positive. 8. **Plan for Token Renewal:** Have a clear flow for how a client application can re-authenticate or re-consent to regain revoked scopes once the context is safe again (e.g., after confirming the new device via email). By implementing this design, you move from a static security model to a dynamic, adaptive one that significantly enhances the security of your API integrations without unnecessarily burdening legitimate users.