HMAC-MD5 Generator

Generate HMAC-MD5 keyed-hash message authentication code. Combines MD5 with a secret key for authentication.

Secret Key
Enter your secret key
Message
Enter text to authenticate
HMAC-MD5
128-bit authentication code

What is HMAC-MD5?

HMAC-MD5 (Hash-based Message Authentication Code using MD5) is a mechanism for message authentication that combines MD5 hash function with a secret cryptographic key. It provides both data integrity and authentication.

Key Features

  • Message Authentication: Verifies both integrity and authenticity
  • Secret Key Required: Uses a shared secret key
  • Keyed-Hash: Combines hashing with cryptographic key
  • Fixed Output: 128-bit hash (32 hex characters)
  • Symmetric: Same key used for generation and verification

How HMAC Works

  1. Input: Message + Secret Key
  2. Process: Special combination of key and message with MD5
  3. Output: Authentication code that proves both integrity and authenticity

Unlike simple hashing, HMAC cannot be computed without the secret key, providing authentication.

Common Use Cases

  • API Authentication: Verify API requests and responses
  • JWT Tokens: Sign JSON Web Tokens
  • Message Verification: Ensure messages haven't been tampered with
  • Cookie Signing: Prevent cookie tampering
  • Webhook Signatures: Verify webhook authenticity

Security Considerations

⚠️ Note: While HMAC-MD5 is still used in some legacy systems, for new applications consider:

  • HMAC-SHA256 for better security
  • HMAC-SHA512 for maximum security
  • MD5's cryptographic weaknesses are less critical in HMAC context due to the key

Example

Message: Hello, World! Secret Key: secret-key-123

HMAC-MD5: 9f1e31c9bb51cb3b5061356f70a5c1b2

The same message with a different key produces a completely different HMAC.