HMAC Generator
Compute keyed HMAC signatures (SHA-1, SHA-256, SHA-512) from a message and secret.
Knowledge Base & Educational Companion: HMAC & Message Authentication
An HMAC (Hash-based Message Authentication Code) combines a secret key with a hash function to prove both the integrity and authenticity of a message. Only holders of the key can produce a valid code.
1. Integrity + Authenticity
A plain hash detects accidental changes; an HMAC also proves the sender knew the shared secret, defending against forged or tampered messages.
2. Webhooks & APIs
Services sign webhook payloads with HMAC so receivers can verify the request genuinely came from them — a cornerstone of API security.
3. Keep the Key Secret
HMAC security depends entirely on the secrecy and length of the key. Anyone who learns the key can forge valid signatures, so treat it like a password.
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