Secure API Design: Authentication, Authorization, Input Validation, and OWASP API Top 10

Calendar February 22, 2026
Security
Intermediate
Api-Authentication, Oauth2-Implementation, Input-Validation, Rate-Limit-Design
Api-Security, Oauth2, Jwt, Authentication, Authorization, Owasp, Rate-Limiting, Input-Validation
Oauth2, Jwt, Openapi, Envoy, Nginx

Secure API Design#

Every API exposed to any network — public or internal — is an attack surface. The difference between a secure API and a vulnerable one is not exotic cryptography. It is consistent application of known patterns: authenticate every request, authorize every action, validate every input, and limit every resource.

Authentication Schemes#

API Keys#

The simplest scheme. The client sends a static key in a header:

GET /api/v1/data HTTP/1.1
Host: api.example.com
X-API-Key: sk_live_abc123def456

API keys are appropriate for:

OAuth2 and OIDC for Infrastructure

Calendar February 21, 2026
Security
Intermediate
Identity-Provider-Configuration, Kubernetes-Oidc, Sso-Integration, Oauth2-Flow-Selection
Oauth2, Oidc, Keycloak, Dex, Oauth2-Proxy, Kubernetes, Sso, Authentication
Keycloak, Dex, Oauth2-Proxy, Kubectl, Kubelogin, Helm

OAuth2 vs OIDC: What Actually Matters#

OAuth2 is an authorization framework. It answers the question “what is this client allowed to do?” by issuing access tokens. It does not tell you who the user is. OIDC (OpenID Connect) is a layer on top of OAuth2 that adds authentication. It answers “who is this user?” by adding an ID token – a signed JWT containing user identity claims like email, name, and group memberships.