OpenID Connect PII Security Best Practices

The login request hits your servers. Behind it is more than an email or a username—it carries personal identifiable information (PII) that demands precision and control. OpenID Connect (OIDC) is the framework that moves this data between systems, but without a clear strategy, you risk leaking PII at the edges.

OIDC builds on OAuth 2.0, adding an identity layer that standardizes how claims about a user are requested and received. These claims often include sensitive PII data like names, email addresses, and profile information. By default, many identity providers expose more than you need. Each unnecessary field increases your attack surface.

The first step is to limit scope. OIDC scopes such as openid, profile, and email control which PII is returned in the ID token. Avoid broad scopes unless required for a feature. When possible, design your authentication flow to request only essential claims.

Secure transport is non-negotiable. All OIDC communication must happen over TLS, and tokens containing PII should never be stored unencrypted at rest. Inspect ID tokens carefully—many developers forget these tokens persist in logs, caches, or error traces. Stripping or encrypting PII before storage reduces long-term exposure risks.

PII minimization extends beyond scopes. UserInfo endpoint requests should be locked down. If your application uses this endpoint to fetch data, audit the returned JSON to ensure only the required properties are included. Some providers allow custom claims; tightly control which ones exist to prevent sensitive leakage.

Token validation is also critical. Verify signatures using the provider’s public keys and reject expired or tampered tokens. This protects against injection attacks that could slip unauthorized PII into your flow.

Finally, document every PII-related decision. Compliance with GDPR, CCPA, or internal governance depends on auditable records of what PII is requested, stored, and shared. Small oversights here can cause major security incidents.

OIDC can move PII safely—if it’s configured with intent and verified at every step. Cut unnecessary claims, lock down scopes, secure transport, monitor logs, and validate tokens.

See how you can configure and test OpenID Connect with PII best practices live in minutes at hoop.dev.