Postman Pre-request script for HMAC Authentication with Kong

This is javascript for use with Postman's pre-request script feature. It generates HTTP request headers for HMAC authentication with Kong. More specifically, Kong's HMAC Authentication Plugin.

The script could easily be modified for use with custom HMAC authentication schemes.

Usage

Copy the contents of postman-pre-request-script.js into the "Pre-request Script" tab in Postman.
Create an environment and add two key-value pairs at Postman's "Manage Environments" settings dialog. keyId containing the ID or username of the API consumer, and secret containing the shared secret key.
Switch to the new environment.
On the "Headers" tab click "Bulk Edit" and paste the following content into the headers field. Note that the Content-Type header must be set manually to the content type of your request. The other headers will be generated automatically by the script.
```
 Authorization:{{auth-header}}
 Date:{{date-header}}
 Content-MD5:{{content-md5}}
 Content-Length:{{content-length}}
 Content-Type:application/json 
```
As shown below:
Send the request.

Modifying Signature Headers

If you don't require all five headers to be included in the signature hash you can comment out the headers you don't want in the javascript as shown below:

var sigHeaders = {
    'request-line' : requestLine,
    'date' : dateHeader,
    //'content-type' : contentType,
    'content-md5' : base64md5,
    'content-length' : contentLength
    };

Debugging the Script

When making modifications to the script it is helpful to check the contents of the generated environment variables. You can do this by clicking on the eye icon next to the environment management button after sending a request.

Reference

HTTP Signatures Specification

License