Testing the Limits of Custom ID-JAG in PingFederate

PingFederate 12.3.3.1 can issue an Identity Assertion JWT Authorization Grant (ID-JAG) via a custom token generator. This much is established. The critical follow-up question, however, is how robust this implementation is under real-world conditions and what its limitations truly are. This series, culminating in Part 4, has explored building the generator, managing it with Terraform, and now, testing its live issuance capabilities without overclaiming its functionality.

The live runner executed 27 distinct checks against a server reporting version 12.3.3.1. These checks confirm that a successful token response was generated and that its signature could be independently verified against the server's published JWKS. Crucially, it also verified that the Terraform configuration remained synchronized with the running state of the PingFederate instance after an apply, indicating successful infrastructure-as-code management. This is useful evidence, but it is not the entire story of a production-ready deployment.

Four Layers of Evidence, Distinctly Handled

The testing methodology employed here is deliberately layered to isolate different aspects of the implementation. This approach provides a clearer picture of where the system succeeds and where it falls short.

  • Java Offline Checks (26): These tests form the bedrock, verifying core cryptographic operations like signing, and examining the behavior of PingFederate's internal parser, selector, and serializer classes using selected components. They ensure the fundamental logic of the generator is sound in isolation.
  • Node Client Tests (24): Moving beyond the Java core, these tests simulate client-side interactions. They focus on the protocol behavior and perform assertion verification using local RSA fixtures. This layer validates that the issued tokens can be correctly processed and verified by a consuming entity, albeit with controlled test data.
  • Terraform Tests (4): As detailed in Part 3, Terraform manages the PingFederate configuration for the custom ID-JAG. These tests, using mocked infrastructure, confirm that Terraform can correctly define, deploy, and manage the resources associated with the generator. The goal here was to ensure repeatable and auditable configuration, not just a sequence of API calls. The result managed eight resources on the local server, and critically, a follow-up plan after application showed no drift from the desired state.
  • Live Issuance Checks (27): This final layer, the subject of this article, brings the generator to the actual PingFederate token endpoint. It confirms that the server accepts valid requests, rejects invalid ones (the focus of the 'without overclaiming' aspect), and produces verifiable assertions.

The separation of these evidence types is deliberate. A successful signature verification (Java offline) doesn't guarantee the client can parse it (Node tests). A working Terraform configuration (Terraform tests) doesn't mean the live endpoint behaves as expected (Live Issuance). Each layer builds confidence, but also highlights that success in one does not automatically imply success in others.

The Generator's Contract: A Small, Explicit Foundation

The custom ID-JAG generator, as implemented, operates on a small, explicit contract. It receives six mapped attributes, which are critical to its function:

  • sub: The validated subject carried through the exchange policy. This is the identity being asserted.
  • subject_client_id: The audience of the validated subject token. This dictates which party the assertion is intended for.
  • subject_exp: The expiry time of the validated subject token, provided in Unix seconds. This ensures the assertion has a limited lifespan.
  • approved_scopes: The scopes approved for the token. This defines the permissions granted.
  • auth_time: The time the end-user authenticated. This provides an audit trail for the authentication event.
  • iss: The issuer identifier. This is the identifier of the PingFederate server issuing the token.

This tight contract, established in Part 2, simplifies the initial development and testing. It focuses the generator on its core task: producing a signed assertion based on specific inputs. However, this explicit contract also defines the boundaries of the proof. The generator issues an assertion for one fixed destination and does not configure downstream redemption or handle more complex scenarios.

What the Live Tests Confirm and What They Leave Open

The 27 live checks confirm that the custom ID-JAG generator successfully produces a signed assertion for a fixed destination when invoked via the PingFederate token endpoint. The signature verification against the server's JWKS is a critical piece of evidence, demonstrating cryptographic integrity. The synchronization between Terraform and the running configuration further validates the operational manageability of this custom component.

However, the live tests do not confirm several vital aspects:

  • Arbitrary Application Acceptance: The tests do not prove that an arbitrary application, not part of this specific test harness, will accept the assertion. Real-world applications may have stricter validation rules, different parsing expectations, or specific requirements not covered by the test client.
  • Complete Cross-App Access Deployment: This proof-of-concept does not demonstrate a full Cross-App Access (XAA) deployment. XAA involves more than just issuing an assertion; it includes mechanisms for token exchange, resource access, and potentially, authorization policies on the resource server.
  • Specification Conformance: While the assertion is signed and verifiable, it has not been tested against every nuanced requirement of the evolving Identity Assertion JWT Authorization Grant specification. Subtle deviations could exist that might cause issues with more compliant or strict relying parties.
  • Error Handling and Rejection Logic: While the tests confirm successful issuance, the extent to which the server correctly rejects malformed requests or requests that should fail based on policy is only partially validated by the 'without overclaiming' aspect. A comprehensive security audit would require exhaustive negative testing.

The project repository, available at https://github.com/darkedges/pf12.3-id-jag-poc, contains the code for this series. It provides the foundation for these tests, but users should be aware of the boundaries of this proof-of-concept when considering production deployments.