HMAC Calculator - SimeonOnSecurity
NOTE: This tool runs entirely in your browser with client-side JavaScript. Your key and message never leave your machine, and the signature is computed locally with the Web Crypto API. Nothing is transmitted or stored.
Signature
Hex
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Base64
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Where HMAC Is Used
- Webhook verification. Providers sign the request body so you can prove it came from them and was not altered in transit.
- API request signing. A shared secret plus the request content produces a signature only a key holder can generate.
- Comparison discipline. Compare signatures with a constant-time function. A normal string comparison leaks how many bytes matched.
Sponsored by The Cyber Sentinels Club
