HMAC Generator
Generate Hash-based Message Authentication Codes (HMAC) for message integrity and authentication.
Configuration
Quick Actions
Common Use Cases
Message
0 characters
Bytes: 0
Secret Key
Length: 0 characters
HMAC-SHA256 (HEX)
HMAC Verification
Enter an HMAC to verify it matches the current message and secret
About HMAC
What is HMAC?
Hash-based Message Authentication Code - cryptographic hash function with a secret key
Purpose
Verify data integrity and authenticity of messages
Security
Provides both integrity and authentication - requires secret key
Algorithm Choice
SHA-256 recommended, avoid SHA-1 for new applications
Common Uses
API authentication, webhook verification, JWT signing, session tokens
Key Management
Keep secret keys secure and rotate them regularly
Verification
Always use constant-time comparison to prevent timing attacks
Standards
Defined in RFC 2104, widely supported across platforms
HMAC Formula:
HMAC(K, m) = H((K ⊕ opad) || H((K ⊕ ipad) || m))
Where K = key, m = message, H = hash function, opad/ipad = padding constants