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Concepts

Kerberos meets OpenID Connect in a handshake of power.

Andrios Robert

• 1 min read

Kerberos has ruled network authentication for decades. It uses tickets and symmetric cryptography to verify identity without sending passwords over the wire. It is fast, proven, and embedded deep in enterprise infrastructure.

OpenID Connect (OIDC) builds identity on top of OAuth 2.0. It is a simple JSON-based protocol for proving who a user is to a web or API service. It trades the closed realm of a Kerberos key distribution center for wide internet reach, browser sessions, and JWT tokens.

Integrating Kerberos with OpenID Connect means bridging on-prem authentication with cloud-native services. It allows legacy systems tied to Kerberos to grant access via OIDC to applications that expect OAuth flows. This avoids password synchronization, keeps existing Kerberos trust chains, and leverages modern identity APIs without ripping out old infrastructure.

Technical flows are clear:

  • A client obtains a Kerberos service ticket from the KDC.
  • An OIDC bridge service validates the ticket.
  • The bridge mints an OIDC ID token or access token, signed with its private key.
  • The token is returned to the client, which uses it with OIDC-compatible applications.

This cross-authentication must handle token lifetimes, replay protection, audience restrictions, and signing algorithms. Common patterns include mapping Kerberos principal names into OIDC subject claims and enforcing scope agreements that align with the original service ticket permissions.

Security teams prefer this approach because it centralizes verification. Kerberos handles internal, controlled traffic. OIDC handles API and web calls across hybrid networks. The bridge becomes the trust link. If compromised, it can be locked down without rewriting the entire identity stack.

For organizations, the Kerberos–OpenID Connect integration is not an experiment. It is a practical upgrade path. It supports SSO across old and new apps. It enables gradual migration to cloud authentication while maintaining compliance rules on-prem.

See Kerberos and OpenID Connect working together in minutes. Try it live on hoop.dev and build the bridge yourself.