Assessing App Attest evidence involves more than cryptographic verification. The expected application, challenge and request context must all match.
Evaluation approach
Handle attestation during key enrollment and assertion verification for subsequent requests. Evaluate application identity, challenge, signature and counter behavior according to the official protocol.
Application example
The server must not accept the same signed request with different content. Include concurrent requests and retries in the test plan.
Limits and considerations
Checking the cryptographic signature while omitting transaction binding can leave replay or context-confusion risks.
The verifier's acceptance conditions
Implement all of Apple's attestation and assertion verification steps. Fields such as application identity, expected challenge context and protocol counters cannot be arbitrarily skipped. Example code should not be assumed to meet every production requirement directly.
Design concurrency, retries and enrollment lifecycle behavior separately. Resetting an entire user's enrollment after any error can cause unnecessary enrollment loops. Link the verification outcome to the user-facing error through a traceable event identifier that contains no unnecessary data.
Checks and decisions
- Separate the enrollment flow
- Bind request content
- Verify counter policy
Keep verification state consistent under concurrent requests.
Sources
The primary references above provide the technical basis. Example workflows and evaluation suggestions are this publication’s explanations, not independent test results for a particular product.