Calculate HMAC-MD5 with a secret key
Enter your message in Text Input and your key in the key field. The generator computes HMAC-MD5 and returns a 32-character hexadecimal authentication code. Both fields use text input, so a key written as 736563726574 is treated as those characters rather than as decoded hex bytes.
A known example uses the message The quick brown fox jumps over the lazy dog and the key key. The result is 80070713463e7749b90c2dc24911e275. Match spaces, capitalization, and any trailing newline when comparing results.
HMAC-MD5 compatibility and alternatives
HMAC combines a hash function with a secret key to authenticate a message. It differs from plain MD5 and from manually hashing a key concatenated with a message. Use the algorithm your existing protocol specifies when reproducing a legacy signature.
RFC 6151 advises against HMAC-MD5 for new protocol designs. For a new integration, the HMAC-SHA256 generator can help test signatures. Keep real secret keys out of shared URLs, screenshots, and issue reports.
Common questions
- Is HMAC-MD5 the same as MD5?
- No. MD5 hashes a message without a key. HMAC-MD5 uses the HMAC construction with a secret key and the MD5 hash function.
- Why does my HMAC-MD5 result differ?
- Check the exact message bytes, the key, and the output encoding. This tool interprets both inputs as UTF-8 text and returns hexadecimal output. Newlines and spaces affect the result.