Aglet

Verify webhook HMAC input handling

Verification must prove that the verifier accepts the intended signed bytes and rejects changed, stale, or unauthenticated deliveries. Test middleware parsing and encoding boundaries, then inspect the disposition and logs. A passing synthetic signature cannot prove raw-body preservation without the altered cases.

Check whether the outcome improved

  1. Define signature outcomes

    Write expected result for exact body, whitespace change, key reorder, altered value, wrong secret, stale timestamp, missing header, and invalid encoding. State whether the event is rejected, retained, or safe to review, without recording sensitive payloads.

  2. Run raw-body cases

    Feed fixtures through the real endpoint stack and compare bytes passed to verification, header parsing, secret label, freshness result, and final disposition. Confirm parsing does not occur before the verifier needs the original body.

  3. Check recovery boundaries

    Repeat a valid delivery after a parser or proxy change, then exercise a bounded rejected delivery and a safe review path. Verify no rejected event reaches side effects and no secret or full payload appears in diagnostic output.

What to carry forward

Accept when exact signed bytes pass, altered or stale inputs fail, and endpoint diagnostics retain only safe correlation. Keep coverage open for unobserved intermediaries. Record fixture bytes, middleware revision, secret label, and final dispositions. Keep verification independent from downstream success.

Technical background: Coinbase developer documentation.

Keep the decision with the work.

Use a Work Item in Aglet to record the problem, the evidence you have, and the next decision. Add an owner and priority, then keep updates in the discussion so the next person can follow the reasoning.

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