ADVANCED // CUSTOM API
MODULE 04 // SECURITY

Authentication Gateway.

Build authentication layers that protect custom endpoints while integrating with identity systems.

AUTHENTICATION STRATEGIES

Custom APIs require authentication to identify callers and authorization to determine access. Integrate with existing identity providers rather than building custom auth.

OAuth2 provides the standard framework: authorization code flow for user-facing apps, client credentials for service-to-service, and JWT tokens for stateless validation.

Implement defense in depth: API keys for identification, OAuth tokens for authorization, mTLS for transport security, and IP allowlisting for additional restriction.

API KEY

Identification

Identifies the client application. Required for all requests. Enables rate limiting per client.

OAUTH

Authorization

Validates user/service permissions. Scopes define allowed operations.

mTLS

Transport

Mutual TLS for service-to-service. Cryptographic client verification.

KNOWLEDGE CHECK // Q04
Why use OAuth2 instead of building custom authentication?