Verify a Veriff webhook or session API response using the X-HMAC-SIGNATURE header before trusting the decision payload
domain: devdocs.veriff.com · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
For webhooks, take the raw request body; for signed GET requests, take the session ID as the signed content
Compute HMAC-SHA256 over that content using your shared secret key, and hex-encode the result
Compare the computed digest to the incoming X-HMAC-SIGNATURE header value with a constant-time comparison
Also confirm the X-AUTH-CLIENT header matches your issued API key before processing further
Only after both checks pass, parse the decision/status payload and update your onboarding record
Known gotchas
The signed content differs by endpoint type — session GET requests sign the session ID itself, while webhooks sign the raw POST body, so reusing one signing routine for both will fail
Any JSON re-serialization or whitespace change to the raw webhook body before hashing breaks the signature match
Signature and client-key checks are separate controls — passing one without the other should still result in rejection
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