QuackyardHMAC Generator
Sign a message with a secret key — HMAC over SHA-256, SHA-512, SHA-1 or MD5 — and check a signature against it.
Signed as the UTF-8 bytes of exactly what's pasted, spaces and newlines included.
The key never leaves your browser: the signature is worked out here in the page, and nothing is sent anywhere.
Algorithm
Written as
Signature · SHA-256
715b29c013bf13a9338bc6fb117f3cbf8c39a96a3a2c5930c1582c2a78ed0308
30 bytes of message, 19 of key.
How webhook signatures are checked
Both services below sign exactly the way this tool does, so the value after the prefix is an HMAC you can check here.
| Service | What it sends | What the signature is made of |
|---|---|---|
| GitHub | X-Hub-Signature-256: sha256=<hex> | HMAC-SHA256 of the raw request body, keyed with the webhook secret. |
| Stripe | Stripe-Signature: t=<time>,v1=<hex> | HMAC-SHA256 of <time>.<raw body>, keyed with the signing secret, whsec_… and all. |
GitHub: paste the raw body as the message, the secret as the key, and what follows sha256= into Check a signature. Stripe: sign t.body — the timestamp from the header, a dot, then the raw body — with the whole signing secret as the key, and compare against v1=.
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