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Sicher Webhook Signature Verifier
x402
Sicher Webhook Signature Verifier is a paid API for AI agents from sicher.halowerk.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-11).
Verifies a webhook payload signature against the canonical signing scheme of a named provider, using constant-time comparison, and returns the reconstructed signed string for debugging mismatches.
Price / call$0.002
Success—
StatusUnknown
How this service works
Providers each build their signing string differently — some sign only the body, others prepend a timestamp, an id, or a version marker in a fixed order — and getting that order wrong produces a mismatch that looks exactly like an attack. This checks the signature the way the named provider actually specifies, with constant-time comparison, and returns the string that was signed so a mismatch can be debugged instead of guessed at.
Output
Returns whether the signature is valid (boolean), the reconstructed string that was signed according to the named provider's specification, and diagnostic details describing why a mismatch occurred, enabling developers to debug signing order or encoding issues without guessing.
Example use cases
Stripe webhook integrity check
“I just received a Stripe webhook and need to verify the signature before processing the payment event — can you validate it using the raw body, the Stripe-Signature header, and our webhook secret, and tell me if it's legit?”
GitHub webhook spoofing detection
“We're getting GitHub webhook events and want to make sure none are spoofed — verify the X-Hub-Signature-256 header against our secret and the raw payload body, and show me the signed string if there's a mismatch.”
Debugging provider signature mismatch
“Our webhook handler keeps rejecting Twilio signatures even though the secret looks right — can you run the verification against the exact body and signature we received and show us what string Twilio actually signed so we can spot the bug?”
Technical details
Endpoint
POSThttps://sicher.halowerk.com/v1/webhook-signature?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need provider-accurate webhook signature verification that faithfully implements the exact signing algorithm (including timestamp prepending, ID ordering, or version markers) as each provider specifies — not a generic HMAC check. It is especially valuable when debugging mismatches because it returns the reconstructed signed string, saving engineers from guessing at signing order issues.
Side effects
- Unknown or unsupported provider name — endpoint cannot construct the signing string
- Missing or malformed signature header — returns validation error
- Incorrect secret provided — signature will not match but the signed string is still returned for debugging
- Malformed request body — signing string construction fails
- Timestamp outside acceptable skew window — may flag as replay attack depending on provider spec
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| body | string | The raw request body exactly as received, not re-serialised. |
| secret | string | The signing secret. |
| headers | object | All request headers; the right one is picked by provider. |
| provider | string | Which provider signed the request. |
| signature | string | The signature header value. Required unless headers is given. |
| timestamp | string | Timestamp, if the provider signs one and it is not in the headers. |
| message_id | string | Message id for schemes that sign one, e.g. Svix. |
| tolerance_seconds | integer | How old a signed timestamp may be. |
Tags
x402
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