Design a plan to migrate an existing authentication system to a new one.

Migrating from Basic Authentication to OIDC involves a phased approach to ensure security and minimize customer impact.

Architecture Changes:

1. Identity Provider (IdP) Integration: Introduce an OIDC-compliant IdP (e.g., Auth0, Okta, Azure AD, or a custom implementation) to manage user identities and issue tokens.
2. API Gateway/Middleware: Implement a layer that intercepts incoming requests. This layer will validate OIDC tokens (access tokens and ID tokens) before forwarding requests to backend services.
3. Client-Side Updates: Modify client applications (web, mobile, CLI) to initiate the OIDC authentication flow (e.g., Authorization Code Flow) with the IdP and include the obtained access token in API requests.
4. Backend Service Updates: Backend services will no longer handle direct username/password authentication. They will rely on the API gateway/middleware to validate tokens and extract user information from them.
5. User Data Migration: Plan for migrating user credentials and profile information from the existing system to the new IdP. This might involve a one-time import or a gradual migration during user re-authentication.

Migration Approach:

1. Phased Rollout: Implement a dual-authentication system temporarily. New users will be onboarded directly to OIDC. Existing users will be migrated gradually.
2. User Re-authentication: Prompt existing users to re-authenticate using the new OIDC flow. This process can be triggered during their next login or via a targeted campaign.
3. Token Validation: The API gateway will initially support both Basic Auth (for legacy requests) and OIDC tokens. As users migrate, Basic Auth will be deprecated.
4. Deprecation Plan: Clearly communicate the deprecation timeline for Basic Authentication to all customers, providing ample notice and support resources.

Rollout Strategy:

1. Internal Testing: Thoroughly test the OIDC integration and migration process with internal users and staging environments.
2. Beta Program: Invite a subset of customers to participate in a beta program to test the new authentication flow and provide feedback.
3. Gradual Rollout: Release the OIDC authentication to a small percentage of the user base, monitoring for issues. Gradually increase the rollout percentage.
4. Communication: Maintain clear and consistent communication with customers throughout the migration, explaining the benefits, process, and any required actions.

Technical Challenges:

• Token Management: Securely handling, storing, and validating OIDC tokens (access, refresh, ID tokens).
• Session Management: Adapting session management strategies to token-based authentication.
• Error Handling: Implementing robust error handling for OIDC flows and token validation failures.
• Integration Complexity: Integrating with the chosen IdP and ensuring seamless communication between components.
• Legacy System Dependencies: Managing dependencies on the old authentication system during the transition.

Impact on Customers:

• Initial Re-authentication: Customers will need to re-authenticate using the new OIDC flow, which might involve a redirect to the IdP.
• API Client Updates: Customers using API clients will need to update their applications to use OIDC flows and include OIDC tokens in requests.
• Potential Downtime: Minimize downtime through careful planning and phased rollout.

Backward Compatibility:

• Temporary Dual Support: Maintain Basic Authentication alongside OIDC for a defined period to allow customers to migrate at their own pace.
• API Versioning: Consider API versioning to gracefully introduce changes that rely on OIDC.