HMAC SHA512 Authentication Pre-request script for Postman

postman-hmac-sha512-preq-request.js

/* Pre-requisite
==================
1) Create an Environment (if you don't already have on) and enable it for your request
2) Add a new Header with key as "Authorization" and value as "{{hmacAuthHeader}}"
3) Add the following Pre-request Script that computes the hmacAuthHeader variable and adds it to the environment
4) Fill your CLIENT_KEY and SECRET_KEY with valid values
*/

function getPath(url) {
    var pathRegex = /.+?\:\/\/.+?(\/.+?)(?:#|\?|$)/;
    var result = url.match(pathRegex);
    return result && result.length > 1 ? result[1] : ''; 
}
 
function getQueryString(url) {
    var arrSplit = url.split('?');
    return arrSplit.length > 1 ? url.substring(url.indexOf('?')+1) : ''; 
}
 
function getAuthHeader(httpMethod, requestUrl, requestBody) {
    var CLIENT_KEY = 'REPLACE_WITH_YOUR_CLIENT_KEY';
    var SECRET_KEY = 'REPLACE_WITH_YOUR_SECRET_KEY';
    var AUTH_TYPE = 'HMAC-SHA512';
         
    var requestPath = getPath(requestUrl);
    var queryString = getQueryString(requestUrl);
    if (httpMethod == 'GET' || !requestBody) {
        requestBody = ''; 
    } else {
        requestBody = JSON.stringify(requestBody);
    }   
         
    var hashedPayload = CryptoJS.enc.Hex.stringify(CryptoJS.SHA512(requestBody));
         
    var timestamp = new Date().toISOString().split('.')[0]+"Z";
    var requestData = [httpMethod, requestPath, queryString, timestamp, hashedPayload].join("\n");
    var hashedRequestData = CryptoJS.enc.Hex.stringify(CryptoJS.SHA512(requestData));
         
    var hmacDigest = CryptoJS.enc.Hex.stringify(CryptoJS.HmacSHA512(hashedRequestData, SECRET_KEY));
    var authHeader = AUTH_TYPE + ' timestamp=' + timestamp + ", client=" + CLIENT_KEY + ', signature=' + hmacDigest;
    return authHeader;
}
 
postman.setEnvironmentVariable('hmacAuthHeader', getAuthHeader(request['method'], request['url'], request['data']));