Hash Mac
Computes a keyed hash (HMAC) of a text or a file, using a secret key stored as a HashMac Key credential.
The Hash Mac action computes an HMAC: a hash of a text or a file mixed with a secret key. Use it to sign a payload for an API that checks an HMAC signature, or to verify a webhook signature you received. The secret key is kept in a credential, not in the process.
Before you start
Create a credential of type HashMac Key and put your secret key in its password field.
Add the action
In the Process Designer toolbox, open Converters โบ Cryptographic and pick Hash Mac (or type Hash Mac in the search box).
Select the credential, then click Configure Hash to fill in the rest.
Inputs and outputs
| Field | Where | Direction | Type | Required | What to put / what you get |
|---|---|---|---|---|---|
| Select HashMac credentials | Panel | Input | Credential | Yes | The HashMac Key credential that holds the secret key. |
| Input File | Configure Hash | Input | File | No* | The file to hash. |
| Input String | Configure Hash | Input | Text | No* | The text to hash. Ignored when Input File is given. |
| Hash | Configure Hash | Input | Option | Yes | The algorithm: HMACMD5, HMACSHA1, HMACSHA256, HMACSHA3_256, HMACSHA3_384, HMACSHA3_512, HMACSHA384 or HMACSHA512. |
| Result | Configure Hash | Output | Text | Yes | The HMAC as lower-case hexadecimal. |
* Fill one of the two. With both empty, the step fails with Both Input file and string are null or empty.
Good to know
- The text and the secret key are both read as UTF-8, and the result is lower-case hex. If the receiving system expects Base64, convert the hex accordingly.
- A credential with an empty password fails the step with
Credential password is null or empty. - Most APIs that sign requests use
HMACSHA256. Check what the other system expects, including exactly which text is signed (body only, or body plus a timestamp). - Without a key, use Hash.